Minimally Invasive Plate Osteosynthesis (MIPO)

AO Manual of Fracture Management Minimally Invasive Plate Osteosynthesis (MIPO)

G On Tong, Suthorn Bavonratanavech

The book is divided into two sections; the first section deals with general principles while the second section deals with the anatomical regions that current MIPO techniques are applicable to.

Martin Allgöwer Professor, Dr hc mult Honorary Chairmain and Founding Menber of AO

The book is written in a simple and easy-to-understand style with many case examples included to provide the reader with a broad spectrum of the type of problems that may be encountered in everyday practice. The book is well illustrated and animations and video clips are included to enhance the learning experience. This book is highly recommended for those surgeons who are interested in learning more about the current practice of MIPO.

www.aofoundation.org

MIPO_Cover_Final.indd 1

Rest of World ISBN 10 3-13-143391-4 ISBN 13 978-3-13-143391-6

The Americas ISBN 10 1-58890-544-6 ISBN 13 978-1-58890-544-4

Tong, Bavonratanavech

The book concerning concepts and cases presented by AO East Asia is another far reaching proof of the new brotherhood of trauma surgeons spreading successfully the AO community advocating early total care of the accident victims described in very detail.

Minimally Invasive Plate Osteosynthesis (MIPO)

This is the first book on the subject of minimally invasive plate osteosynthesis (MIPO) that has been published. It includes current recommendations on this subject as taught in the AO MIPO Courses organized by AO East Asia. It should serve as a useful guide for those trauma surgeons who lack the experience but wish to learn more about this subject before starting to do the actual surgical procedures. Even for those with some experience in this field, the book contains many useful and practical tips that can be added to one’s armamentarium.

AO Manual of Fracture Management

Minimally Invasive Plate Osteosynthesis (MIPO) Concepts and Cases presented by AO East Asia

AO Teaching Videos on DVD-ROM included

9/5/06 1:43:08 PM

G On Tong

Suthorn Bavonratanavech

AO Manual of Fracture Management

Minimally Invasive Plate Osteosynthesis (MIPO)

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G On Tong

Suthorn Bavonratanavech

AO Manual of Fracture Management

Minimally Invasive Plate Osteosynthesis (MIPO)

440 Illustrations 400 Photos AO Teaching Videos and Animations on DVD-ROM

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Illustrations: tadpole gmbh, 8048 Zürich Layout and typesetting: AO Publishing, CH-8600 Dübendorf

Library of Congress Cataloging-in-Publication Data is available from the publisher.

Hazards Great care has been taken to maintain the accuracy of the information contained in this publication. However, the publisher, and/or the distributor, and/or the editors, and/or the authors cannot be held responsible for errors or any consequences arising from the use of the information contained in this publication. Contributions published under the name of individual authors are statements and opinions solely of said authors and not of the publisher, and/or the distributor, and/or the AO Group. The products, procedures, and therapies described in this work are hazardous and are therefore only to be applied by certified and trained medical professionals in environments specially designed for such procedures. No suggested test or procedure should be carried out unless, in the user‘s professional judgment, its risk is justified. Whoever applies products, procedures, and therapies shown or described in this work will do this at their own risk. Because of rapid advances in the medical sciences, AO recommends that independent verification of diagnosis, therapies, drugs, dosages, and operation methods should be made before any action is taken. Although all advertising material which may be inserted into the work is expected to conform to ethical (medical) standards, inclusion in this publication does not constitute a guarantee or endorsement by the publisher regarding quality or value of such product or of the claims made of it by its manufacturer. Legal restrictions This work was produced by AO Publishing, Davos, Switzerland. All rights reserved by AO Publishing. This publication, including all parts thereof, is legally protected by copyright. Any use, exploitation or commercialization outside the narrow limits set forth by copyright legislation and the restrictions on use laid out below, without the publisher‘s consent, is illegal and liable to prosecution. This applies in particular to photostat reproduction, copying, scanning or duplication of any kind, translation, preparation of microfilms, electronic data processing, and storage such as making this publication available on Intranet or Internet. Some of the products, names, instruments, treatments, logos, designs, etc. referred to in this publication are also protected by patents and trademarks or by other intellectual property protection laws (eg, ”AO”, ”ASIF”, ”AO/ASIF”, ”TRIANGLE/GLOBE Logo” are registered trademarks) even though specific reference to this fact is not always made in the text. Therefore, the appearance of a name, instrument, etc. without designation as proprietary is not to be construed as a representation by the publisher that it is in the public domain. Restrictions on use: The rightful owner of an authorized copy of this work may use it for educational and research purposes only. Single images or illustrations may be copied for research or educational purposes only. The images or illustrations may not be altered in any way and need to carry the following statement of origin ”Copyright by AO Publishing, Switzerland.”

Check hazards and legal restrictions on www.aofoundation.org/legal Copyright © 2007 by AO Publishing, Switzerland, Clavadelerstrasse, CH-7270 Davos Platz Distribution by Georg Thieme Verlag, Rüdigerstrasse 14, D-70469 Stuttgart, Germany and Thieme New York, 333 Seventh Avenue, US-New York, NY 10001 Acknowledgments: Picture in Fig 1-2b courtesy of Wilson JW (2002) Blood supply to developing, mature, and healing bone. Sumner-Smith G (ed), Bone in Clinical Orthopedics. Stuttgart New York: Georg Thieme Verlag, 86. Picture in Fig 2-3 courtesy of Rand JA et al (1981) A comparison of the effect of open intramedullary nailing and compression-plate fixation on fracture site blood flow and fracture union. J Bone Joint Surg; 63A:427–442. Picture Fig 2-4 courtesy of Rahn BA (2002) Bone healing: histological and physiological concepts. Sumner-Smith G (ed), Bone in Clinical Orthopedics. Stuttgart New York: Georg Thieme Verlag, 307. ISBN 10 3-13-143391-4 (GTV) ISBN 13 978-3-13-143391-6 (GTV)

ISBN 10 1-58890-544-6 (TNY) ISBN 13 978-1-58890-544-4 (TNY)

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Table of contents Foreword Preface

vii x

Contributors

xii

Acknowledgments

xiv

Principles

1

2

359

3

Mechanobiology

9

—Kok-Sun KHONG, Ramakrishna KOTLANKA, Dhanjoo N GHISTA 3

Glossary

History and evolution of MIPO

—G On TONG

Instruments

23

—Suthorn BAVONRATANAVECH 4

Implants

33

—Frankie KL LEUNG 5

Intraoperative imagin g

47

—Kok-Sun KHONG, Fareed KAGDA 6

Computer assisted surgery in MIPO

57

—Merng Koon WONG 7

Reduction techniques

67

—Frankie KL LEUNG, Shew-Ping CHOW 8

Decision making and preoperative planning

79

—Tadashi TANAKA 9

Postoperative management

93

—Tadashi TANAKA, Toru SATO 10

Complications and solutions

101

—Theerachai APIVATTHAKAKUL

v

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Cases

11

Humerus, proximal

121

16

Tibia and fibula, proximal

255

—Merng Koon WONG, Suthorn BAVONRATANAVECH, Frankie KL LEUNG

—Merng Koon WONG, Suthorn BAVONRATANAVECH, Frankie KL LEUNG

11.1 Humerus, proximal: extraarticular unifocal fracture,

16.1 Tibia and fi bula, proximal: complete articular fracture,

nonimpacted, metaphyseal—11-A3

131

11.2 Humerus, proximal: extraarticular unifocal fracture,

articular simple, metaphyseal simple—41-C1

nonimpacted, metaphyseal—11-A3 with diaphyseal

12

pure split—41-B1

involvement

137

Humerus, shaf t

145

12.1 Humerus, shaft: wedge fracture, bending wedge—12-B2 157

metaphyseal, multifragmentary—41-A3 with

17

diaphyseal involvement

275

Tibia and fibula, shaft

281

12.2 Humerus, shaft: complex fracture, irregular—12-C3

163

—Theerachai APIVATTHAKAKUL, Kok-Sun KHONG

12.3 Humerus, shaft: complex fracture, spiral—12-C1

169

17.1 Tibia and fi bula, shaft: wedge fracture,

12-B3

173

17.2 Tibia and fi bula, shaft: wedge fracture,

Femur, proximal

181

12.4 Humerus, shaft: wedge fracture, fragmented wedge—

fragmented wedge–42-B3

—Suthorn BAVONRATANAVECH, Theerachai APIVATTHAKAKUL

18

13.1 Femur, proximal: extraarticular fracture,

203

Femur, shaft

209

Femur, distal

317

articular simple, metaphyseal, multifragmentary—

19

43-C2

321

Clavicle

327

—Vajara PHIPHOBMONGKOL 339

19.2 Clavicle, shaft: simple transverse fracture—OTA 15-A3 347

14.1 Femur, shaft: wedge fracture, fragmented wedge—

15

305

19.1 Clavicle, shaft: spiral wedge fracture—OTA 15-B1

—Suthorn BAVONRATANAVECH, Theerachai APIVATTHAKAKUL

14.2 Femur, shaft: wedge fracture, spiral wedge—32-B1

Tibia and fibula, distal

simple—43-A1

199

pertrochanteric, multifragmentary—31-A2

32-B3

299

18.2 Tibia and fi bula, distal: complete articular fracture,

13.3 Femur, proximal: extraarticular fracture,

14

fragmented wedge–42-B3

18.1 Tibia and fi bula, distal: extraarticular fracture, 193

13.2 Femur, proximal: extraarticular neck fracture, subcapital with slight displacement—31-B1,

295

—Young-Soo BYUN, Chang-Wug OH

intertrochanteric—31-A3 and complex spiral diaphyseal fracture—32-C1

269

16.3 Tibia and fibula, proximal: extraarticular fracture,

—Theerachai APIVATTHAKAKUL

13

265

16.2 Tibia and fi bula, proximal: partial articular fracture,

221 225

231

19.3 Clavicle, shaft: simple oblique fracture—OTA 15-A2 with marked displacement

353

19.4 Clavicle, shaft: simple transverse fracture—OTA 15-A3 357

—Suthorn BAVONRATANAVECH, Frankie KL LEUNG 15.1 Femur, distal: partial articular fracture of the medial condyle—33-B2 and spiral wedge shaft fracture—32-B1 243 15.2 Femur, distal: extraarticular fracture, simple—33-A1 and simple spiral shaft fracture—32-A1 15.3 Femur, distal: extraarticular fracture, simple 33-A1

247 251

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Foreword Martin Allgöwer

It is a real privilege to be asked for a short greeting in your excellent and extremely competent “AO Manual of Fracture Management—Minimally Invasive Plate Osteosynthesis (MIPO)” published by G On Tong and Suthorn Bavonratanavech. The book concerning concepts and cases presented by AO East Asia is another far reaching proof of the new brotherhood of trauma surgeons spreading successfully the AO community advocating early total care of the accident victims described in very detail. The authors are giving every evidence of their seasoned mastership in the surgery of trauma—congratulations!

Martin Allgöwer Professor, Dr hc mult Honorary Chairmain and Founding Member of AO Basel, June 2006

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Foreword Reto H Babst

The aim to add minimal further trauma to the traumatized patient is a long standing tradition in orthopedic trauma surgery. Minimal access surgery or minimal invasive surgery (MIS) was fi rst introduced with external fi xation in fracture fi xation in the 19th century, with development of arthroscopic surgery and endomedullary nailing in the 20th century. The cosmetically appealing small incisions were not the striking factors that prompted the rapid progression of these minimal invasive techniques but the biological advantages, such as undisturbed fracture healing, less soft-tissue compromise and fewer infectious complications associated with faster recovery. The step from the observation of the similarities of the fracture healing pattern when using an extramedullary splint applied by indirect reduction technique, as seen when using an endomedullary nail, to the development of the submuscular plating technique was attempted during the late 1990s. New plate designs like the LISS and the LCP some years ago supported the rapid progression of this new approach to fracture treatment by minimally invasive plate osteosynthesis (MIPO) all over the world. Since there is no evident biological marker to defi ne surgical invasiveness, minimally invasive osteosynthesis should be geared to some basic principles and defi nitions. Minimally invasive osteosynthesis (MIO) includes all forms of fracture fi xation that: use small soft-tissue windows to allow insertion of implants or instruments cause minimal additional trauma to the soft tissue and fracture fragments

use indirect (traction table, external fi xator, distractors, manual traction) or direct reduction techniques (K-wires, reduction screws, percutaneous reduction forceps, joysticks) can apply the biomechanical concepts of relative stability or, exceptionally, absolute stability. By this defi nition, MIO includes all types of percutaneous fracture fi xation such as external fi xation, closed intramedullary nailing, percutaneous K-wire or screw fi xation as well as MIPO. Thanks to the AO East Asian Section we have this book in hand which has undertaken the challenge to combine their accumulated practical knowledge of the application of MIPO techniques with the well-known principles of fracture treatment by the AO philosophy. The different chapters cover step by step the different prerequisites to apply MIPO techniques successfully. They not only describe the principles of critical case analysis, preoperative planning, mechanobiology and radiation hazards but also stress the importance of the different direct and indirect reduction techniques and the necessary instruments to provide MIPO with minimal additional softtissue damage. The limited view of the fracture site makes this technique more demanding than ORIF, with the potential for resultant malunion. In addition, direct percutaneous fracture reduction has the hazard of neurovascular damage. Prevention of complications and possible solutions are also included in this book as is computer assisted navigation as a potential tool to overcome some of MIPO’s shortcomings.

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The practical application of MIPO techniques in the different skeletal regions, even though they reflect personal preferences, give invaluable step-by-step information to the experienced surgeon. MIPO techniques represent a fascinating new armamentarium in fracture fi xation, which is made easier with the LCP technology and the different available MIS instruments, which were developed to cause less additional damage to the soft tissue and the bone. The biological advantage of MIPO, however, is only assured when we adhere to the basic principle of fracture care. MIPO should not serve as an excuse for a badly performed osteosynthesis! With this in mind MIPO will continue to develop its potential to reduce bone and soft-tissue healing problems and to speed rehabilitation.

Reto H Babst, MD Professor and Chairman Department of Surgery Chief of Trauma Surgery Kantonsspital Luzern Switzerland Luzern, June 2006

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Preface The fi rst AO minimally invasive plate osteosynthesis (MIPO) Course in East Asia was held in Singapore on April 14–17, 2004. Although minimally invasive osteosynthesis (MIO) courses had been previously conducted elsewhere in the world, the Singapore course was the fi rst official AO Course dedicated to MIPO and the most comprehensive to date. It was also the fi rst to include cadaveric workshops.

Regional Combined AO Courses. It is worthwhile noting that a significant part of these courses was drawn from contributions by the AO East Asia MIPO Study Group, which was set up with the specific aims of doing research and improving the educational content and teaching methods of MIPO techniques. Likewise, the work of this group constitutes the basis of a significant part of this book.

The Singapore MIPO Course was also remarkable for two other reasons. Firstly, a significant number of the faculty members were from East Asia and unlike most other AO Courses, these regional faculty members made presentations that were in many ways original and based on their own work and experience. They showed many novel ways of performing MIPO and also introduced some innovative instruments that were fabricated locally to facilitate the surgical procedures. This made a strong impression, not only among the course participants, but also among the distinguished international faculty members. This marked the start of a strong collaborative effort between the international and regional experts in the field of MIO which culminated in the invitation of Dr Theerachai Apivatthakakul, who is one of the members of the AO East Asia MIPO Study Group, to join the MIO Expert Group of the AO Technical Commission (AOTK). The second remarkable feature was that the course was extremely well received despite the fact that MIPO was a relatively new method of fracture treatment. In fact, the course proved to be so successful that the course format was adopted to serve as a template for future AO MIPO Courses. The demand for MIPO Courses was so great that before long, there was a clamor for the course to be repeated elsewhere in the East Asian region. Thus, the Hong Kong AO Course was held in 2005 and most recently, in 2006, the course was conducted in Chiang Mai, Thailand, as part of the

It became obvious that there was a tremendous interest in the application of MIPO principles and techniques by orthopedic surgeons subspecializing in musculoskeletal trauma. The trend toward biological methods of fracture fi xation was gathering momentum and MIO was a logical step toward realizing this aim. It would not be realistic for everyone interested in learning the intricacies of MIPO techniques to attend a MIPO Course before embarking on this type of surgery. Furthermore, there has so far not been any manual type of book written on the subject. Hence the object of this book is to fulfi ll such a need. This book is an attempt to introduce the reader to the basic principles and concepts of MIPO and illustrate, by way of clinical case examples, the way these concepts are put into practice. It is by no means a defi nitive work. MIPO is a relatively recent phenomenon and is evolving at a rapid rate, which is why it is so exciting. New approaches are being described and new implants and instruments are being introduced to make the procedures easier and more reproducible. However, the important thing is to understand the principles and to apply them correctly. While it is good to have the latest instruments and implants, these are by no means absolutely essential. Conventional implants can be adapted for MIPO surgery and the results can be just as gratifying as shown in many of the cases illustrated in this book.

x

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It is hoped that this book will provide the reader with the starting point for treating fractures using MIPO techniques. It is also hoped that the book will provide a stimulus for the surgeon to develop an interest in this subject and as the experience increases, to be able to critically evaluate the current methods that are being used and make contributions for their improvement. Much remains to be done in the field of MIPO and many discoveries and innovations are waiting to be made. It is hoped that this book can provide the catalyst for this to occur.

G On Tong Singapore, July 2006

Suthorn Bavonratanavech Bangkok, July 2006

xi

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Contributors Editors and authors

Authors

G On TONG, FAMS, MBBS, MMED, MCH, FRCS

Theerachai APIVATTHAKAKUL, MD

Orthopaedic Associates

Trauma Division, Department of Orthopaedics

Mount Elizabeth Hospital

Faculty of Medicine, Chiang Mai University

16-03/04, Mount Elizabeth Medical Centre

TH-Chiang Mai 50200

3 Mount Elizabeth SG-Singapore 228510

Young-Soo BYUN, MD PhD Chief, Department of Orthopedic Surgery

Suthorn BAVONRATANAVECH, BSC, MD

Taegu Fatima Hospital

Thai Board of Orthopedic Surgery

576-31 Sinam-Dong Dong-Gu

Orthopaedic Center

KR-Taegu 701-600

Bumrungrad Hospital 33 Sukhumvit 3 (Soi Nana Nua)

Shew-Ping CHOW, MBBS, LMCC, FRCS, FACS, MS, FHKAM

Sukhumvit Road Klongtoey

Professor

TH-Wattana, Bangkok 10110

Department of Orthopaedics and Traumatology University of Hong Kong Medical Centre 5/F, Professorial Block, Queen Mary Hospital HK-Pok Fu Lam Dhanjoo N GHISTA, PhD Professor Chief, Bioengineering Division Nanyang Technological University 50 Nanyang Avenue SG-Singapore 639798 Fareed KAGDA, MBBS, FRCS, FRCSEd (Orth) Consultant, Division of Orthopaedic Trauma Department of Orthopaedic Surgery National University Hospital 5 Lower Kent Ridge Road SG-Singapore 119074

xii

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Authors

(cont)

Kok-Sun KHONG, MBBS, Mmed (Surg), FRCSG, FAMS

Toru SATO, MD

KS Khong Orthopaedic Practice

Chief of Orthopedic Surgery

16-03/04 Mt Elizabeth Medical Centre

National Hospital Organization Okayama Medical Center

3 Mt Elizabeth

Tamasu 1711-1, Okayama City

SG-Singapore 228510

JP-Okayama

Ramakrishna KOTLANKA, B Eng, PhD

Tadashi TANAKA, MD, DMSc

Research Scholar

Vice-director

Nanyang Technological University

Kimitsu Chuo Hospital

50 Nanyang Avenue

1010 Sakurai, Kisarazu

SG-Singapore 639798

JP-Chiba 292-8535

Frankie KL LEUNG, MD, MBBS, FRCS, FHKCOS, FHKAM

Merng Koon WONG, MD, MBBS, FRCS, FAMS

Consultant Orthopaedic Surgeon

Director of Orthopaedic Trauma

Department of Orthopaedics and Traumatology

Director of AO Centre Singapore

University of Hong Kong Medical Centre

Department of Orthopaedic Surgery

5/F, Professorial Block, Queen Mary Hospital

Singapore General Hospital

HK-Pok Fu Lam

Outram Road SG-Singapore 169608

Chang-Wug OH, MD Department of Orthopedic Surgery Kyungpook National University Hospital 50 Samdok 2ga, Chung-Gu KR-Taegu 700-721 Vajara PHIPHOBMONGKOL, MD, Group Captain Chief of Medical Education Department Department of Orthopaedic Surgery Bhumibol Adulyadej Hospital Royal Thai Airforce 171 Phaholyothin Road, Klongtanon, Saimai TH-Bangkok 10220

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Acknowledgments This book is the result of a collaborative effort by many people who have put in many hours of hard work. The Editors, in particular, wish to express their deep appreciation and gratitude to the following: David Helfet, Chairman of the AO Documentation and Publishing Foundation, whom we approached and broached the idea of producing this book and who agreed to support the project without the slightest hesitation. Professor Martin Allgöwer for writing the foreword of this book.

Roger Kistler, who was responsible for preparing the overall layout of this book. The Editors made multiple changes to the text and layout in order to improve the language and content of the chapters. Roger obligingly incorporated the changes and made the necessary adjustments to come out with the fi nal version of this book. The team of illustrators working for AO Publishing who have made the wonderful and clear illustrations and animations and who have shown great patience and tolerance to the many requests for changes that have been asked of them. The AO Video Team in Davos who edited our videos to ensure that they are of a high quality.

Reto Babst for writing the foreword of this book. Urs Rüetschi, Head of AO Publishing, who helped and guided us through every stage of the production of this book.

Members of the AO East Asia MIPO Study Group whose work and ideas has been the inspiration for this book. All the authors who have contributed to this book.

Andy Weymann, Head of AO Education Concepts, who provided invaluable advice whenever the Editors were faced with seemingly insoluble problems. Renate Huter, Project Coordinator from AO Publishing, who was assigned to do this project. Renate has demonstrated great professionalism in her work and shown infi nite patience in her dealings with us. Always approachable, she was prepared to travel great distances so that she could meet up with us to discuss the project. Her enthusiasm and attention to detail was the main driving force behind the successful completion of this book.

Members of AO East Asia whose unstinting support had made this book possible. The many AO surgeons and colleagues who have provided many valuable ideas and suggestions that have helped to make this book a reality. Our wives, Chew Ching and Sinaporn, whose support and encouragement have given us the strength to see this book through to its conclusion.

G On Tong, Suthorn Bavonratanavech

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Principles

1

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2

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Author

1

G On TONG

History and evolution of MIPO

In the fi rst edition of “Technique of Internal Fixation of Fractures” published in 1965, the founding fathers of the AO laid down the following theoretical and practical principles of rigid internal fi xation: Anatomical reduction Rigid fi xation of fragments Preservation of vascularization of the bone fragments In their elaboration of these principles, the authors stated that direct healing of bone had become a clinical and radiological concept. It was also called “fracture union without visible callus formation”. They believed that any excess callus should be considered detrimental, regarded as a kind of “keloid” of the bone, and indicated movement at the fracture site. Any radiologically visible callus formation during fracture healing after internal fi xation was regarded as a warning that should initiate appropriate action. Union without radiologically visible callus, on the other hand, appeared to be the most desirable form of healing. The healing of a fracture without callus could be regarded as radiological evidence of continuous rigid fi xation.

The principles most attractive to surgeons were those of anatomical reduction and stable internal fi xation, possible explanations being that these were the more visible and tangible of the principles as the results could be seen on x-rays. Furthermore, practical exercises at AO Courses were conducted using plastic bones stripped of soft tissues, thus giving the false impression that the soft tissues could be ignored. To be fair, in those cases of fractures treated by anatomical reduction and stable fi xation with successful outcomes, and there were many, the results were impressive—patients were regaining painfree mobility and function of their injured limbs shortly after surgery. “Fracture disease” soon became a thing of the past. However, despite the inclusion of preservation of blood supply

These views were further supported by the experimental demonstration of direct bone healing by Willenegger and Schenk. The trend, therefore, was for all fractures to be anatomically reduced and rigidly fi xed, with direct bone healing without visible callus formation as the desired end result (Fig 1-1). Subsequent editions of the “Manual of Internal Fixation” restated the treatment principles as: Anatomical reduction Stable internal fi xation Preservation of blood supply Early pain-free mobilization of muscles and joints adjacent to the fracture

a Fig 1-1a–b

b X-rays of a diaphyseal fracture fi xed with lag screws and

compression plate showing signs of direct bone healing.

3

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as one of the original treatment principles, and the emphasis on careful handling of soft tissue during surgery, these two elements of fracture management did not receive as much attention from the orthopedic community. During this time, research and development were directed at improving the rigidity of internal fi xation. The concepts of interfragmental compression with lag screws and compression plates, fi rst with the articulating tension device and then with dynamic compression plates (DCP), were introduced. However, it soon became apparent that rigid internal fi xation of fractures did not always produce the desired end result. Instances of sepsis, sequestrum formation, delayed or nonunion, and refractures were observed.

a

Research into these failures led to the discovery of the phenomenon of temporary porosis in the area of the footprint of the plate on bone. The cause of this was considerable damage to the periosteal circulation resulting at the interface between the implant and the bone (Fig 1-2).

Studies using special undercut plates showed that the grooves in the plates reduced vascular damage and mitigated bone porosis. This led to the development of a special undercut plate, the limited contact dynamic compression plate (LC-DCP) (Chapter 4 Implants: Fig 4-6).

b

Fig 1-2a–b a

Phenomenon of temporary porosis.

b

Photomicroangiograph of a transverse section of femur from a mature dog, 6 weeks after placement of a plate. The cortex at the 12 o’clock position, which was directly under the plate is devoid of arterioles, whereas the remainder of the cortex is vascular and viable.

4

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1

History and evolution of MIPO

Thus, the fi rst moves away from mechanical stability of internal fi xation toward biological internal fi xation were made.

Similarly, the strain in fractures with a larger gap width was also reduced.

Further evidence that absolute rigidity was not always necessary for fracture union came from the observation that fractures with flexible fi xation also heal, albeit with callus formation. Such examples of flexible fi xation or splinting came from intramedullary nails, external fi xators, internal fi xators, bridging, and wave plates. In fact, indirect healing often led to early and reliable solid bone union.

It became apparent that anatomical reduction and rigid internal fi xation were not absolutely necessary to achieve union in multifragmentary diaphyseal fractures. Fracture reduction in multifragmentary diaphyseal fractures became simpler and consisted mainly of regaining length, rotation, and axial alignment.

The development of indirect methods of fracture reduction for diaphyseal fractures using the principle of ligamentotaxis led to the avoidance of further damage to the blood supply of the fracture fragments, which accompanied direct manipulation of the fracture ends. Furthermore, it was shown that internal fi xation based only on reducing the mobility of the fracture fragments, without contact between the bone fragments, could result in solid healing. Thus, multifragmentary fractures fi xed with bridging plates demonstrated high union rates without the need for bone grafting (Fig 1-3). The explanation for this was based on the concept of interfragmentary strain. The concept of interfragmentary strain states that fractures with a single, narrow gap are very intolerant of even minute amounts of displacement due to deformation of repair tissues, while multifragmentary fractures can tolerate a greater degree of instability as the overall displacement is shared between many fracture gaps.

a Fig 1-3a–b

b X-rays of a multifragmentary diaphyseal fracture fi xed

with a bridging plate showing union with callus formation.

5

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Thus the stage was set for the progression to more biological methods of fracture fi xation, namely minimally invasive osteosynthesis (MIO). MIO is not a new concept in orthopedic surgery. Closed intramedullary nailing, and percutaneous fi xation of fractures using screws and K-wires had been performed with satisfactory results. The application of plates using minimally invasive surgical techniques, however, was not carried out until the advent of the internal fi xator system which had as its main objective the elimination of the ill effects of plate– bone contact.

The introduction of the PC-Fix was the fi rst step in the realization of the biological advantages of locking head screws (LHS), which preserve both the periosteal and endosteal blood supply. Furthermore, these screws, being self-drilling and selftapping, offered the advantage of simple handling. Following in the footsteps of the PC-Fix was the less invasive stabilization system (LISS), which is described in Chapter 4. It was designed for application in the metaphyseal and epiphyseal areas of, fi rst, the distal femur (Fig 1-4), and then, the proximal tibia. The LISS could be considered the first plate that was specifically designed and instrumented for application using a minimally invasive submuscular approach.

The LISS has a special insertion handle which facilitates the introduction of the implant submuscularly and, at the same time, acts as a drill guide for accurate insertion of the screws through separate small stab wounds. The LHS, which are used with this system, also offer angular stability to the construct. The locking compression plate (LCP) was the third in the series of internal fi xators to be introduced and has the unique feature that it can be used either as a standard dynamic compression plate or as an internal fi xator due to the ingenious design of a special combination plate hole (Chapter 4 Implants: Fig 4-3).

a Fig 1-4a–b example.

b Less invasive stabilization system (LISS) and a case

The LCP can be used for diaphyseal fractures and when applied in the internal fi xator mode, offers the advantage of maintenance of primary reduction of the fracture while avoiding any secondary loss of reduction under load (Fig 1-5).

6

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1

History and evolution of MIPO

This feature makes the LCP suitable for minimally invasive application as it eliminates the need for accurate contouring of the plate to the bone. Another advantage is that, with the use of self-drilling, self-tapping LHS, the need for drilling, measuring, and tapping is no longer necessary. Experimental studies have also confi rmed the advantage of minimally invasive plate osteosynthesis (MIPO) in the femur in preserving the integrity of the perforating arteries as well as the nutrient arteries. Further developments in the field of MIPO included the introduction of new types of LCP designed for use in specific

anatomical regions such as the proximal and distal humerus, distal femur, proximal and distal tibia (Chapter 4 Implants: Fig 4-4). At the same time, instruments that facilitate the surgical procedure are being introduced. Multicenter trials are being conducted to test the efficacy of these new methods, and research is ongoing. Although MIPO is a relatively new concept in fracture treatment, it is slowly gaining acceptance because the underlying principles are sound. Improved instruments and implants are being developed and, with ongoing research and clinical trials, it has the potential of becoming one of the mainstays of fracture management in the years to come.

Suggested reading Farouk O, Krettek C, Miclau T, et al (1997) Minimally invasive plate osteosynthesis and vascularity: preliminary results of a cadaver injection study. Injury; 28(1):A7–A12. Mast J, Jakob R, Ganz R (1989) Planning and Reduction Technique in Fracture Surgery. 1st ed. Berlin Heidelberg New York: Springer-Verlag. Müller ME, Allgöwer M, Schneider R, et al (1979) Manual of Internal Fixation. Berlin Heidelberg New York: Springer-Verlag. Müller ME, Allgöwer M, Schneider R, et al (1991) Manual of Internal Fixation. 3rd ed. Berlin Heidelberg New York: Springer-Verlag. Müller ME, Allgöwer M, Willenegger H (1965) Technique of

a

b

Internal Fixation of Fractures. Berlin Heidelberg New York: SpringerVerlag.

Fig 1-5a–b

X-rays of a distal tibial fracture fi xed by the MIPO

method with a metaphyseal LCP.

Rüedi TP, Murphy WM (2001) AO Principles of Fracture Management. Stuttgart New York: Georg Thieme Verlag.

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2

Mechanobiology

1

Introduction

9

2

Mechanobiology of fracture repair

9

2.1

Mechanical influence on the fracture repair phases

9

2.1.1

Phase of inflammation and tissue response

2.1.2

Phase of intramembranous and endochondral ossification

2.1.3

Phase of fracture consolidation

2.1.4

Phase of bone remodeling

2.2

Biomechanics of fracture callus

10

2.3

Stability in fracture healing

12

2.3.1

Absolute stability

2.3.2

Relative stability

3

The application of gap strain theory

3.1

Fracture gap strain

13

3.2

Osteosynthesis with plate fixation

14

4

Mechanobiology in fracture fixation

67

4.1

Important aspects of the plate

14

4.2

Important aspects of screws

15

4.2.1

Screw design

4.2.2

Number of screws in a plate

4.2.3

Influence of screw placement relative to the fracture site

13

4.3

Bone–plate interface

17

4.4

Helical plating

18

4.5

Choosing relative stability in MIPO

19

5

Biomechanical considerations in preoperative planning

19

6

Common errors

20

7

Summary

20

8

Suggested reading

21

8

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Authors

2 1

Kok-Sun KHONG, Ramakrishna KOTLANKA, Dhanjoo N GHISTA

Mechanobiology Introduction

Current thinking in fracture fi xation is moving toward a symbiotic link between biology and mechanics, rather than regarding them as separate entities in the healing process of fractured bones. The purpose of this chapter is to instruct the trauma surgeon in approaching fracture fi xation in a way that maximizes healing potential such that both biology and mechanics become force-multipliers of each other. This new process is the application of “mechanobiology” and should become more important as less invasive surgical techniques become standard in the armamentarium of the surgeon. Mechanobiology is the embodiment of Julius Wolff’s Law, which states: “The form of a bone being given, the bone elements place or displace themselves in the direction of the functional pressure and increase or decrease their mass to reflect the amount of pressure.” The surgeon needs to understand how to influence the process of bone healing in any given fracture. It is clearly understood that careful soft-tissue handling is very important in preserving blood supply to injured bone. In addition, the outcome of reliable and predictable fracture healing can be influenced by mechanical devices sharing load in unstable fracture patterns. Hence it is important that osteosynthesis is directed at producing a mechanically friendly environment for optimal fracture healing.

2

Mechanobiology of fracture repair

2.1

Mechanical influence on the fracture repair phases

2.1.1

Phase of inflammation and tissue response

As with all tissue-repair mechanisms, the inflammatory phase is mandatory, so that chemotactic factors and cytokines will induce host defense cells as well as highly vascularized repair granulation tissue to form around the damaged and necrotic bone ends. With high local tissue oxygen, fibrogenic tissue will proliferate to provide an initial scaffold between the fracture ends. This phase lasts from the fi rst 24–48 hours of injury into the fi rst week. Granulation tissue can tolerate 100% strain and mechanics do not seem to play a major role during this phase, but surgery should not devascularize this repair tissue. Here lies the main reason for minimally invasive procedures. Medullary blood supply to the diaphysis is important for bone healing, and intramedullary nailing disrupts this source. Periosteal blood flow alone cannot reach the endosteum and endosteal callus may be inhibited. Plate fi xation preserves the medullary and metaphyseal vessels as well as periosteal vessels on the opposite side of the “footprint” caused by the plate. The internal fi xator aims to preserve blood flow under the plate by reduced contact with the bone. 2.1.2

Phase of intramembranous and endochondral ossification

Under conditions of low oxygen as the inflammatory phase passes, hyaline and fibrocartilage differentiation will occur. This process begins within 48 hours after injury and may peak at 9–14 days, depending on the tissue condition. It also follows the peak fracture blood flow at 2 weeks. Osteogenic factors then cause further differentiation of chondroid tissue into bone, much in the way as an ossification center forms during normal growth. Intramembranous ossification occurs as hard 9

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fracture callus further from the fracture site, while endochondral ossification occurs as soft callus around the fracture ends. Mechanical stability allows metaplasia of cartilage to bone. If excessive motion is applied to the bone ends there will be increased vascularity and fibrogenic tissue will persist, resulting in nonunion. Goodship and Kenwright, however, demonstrated that bony enhancement with interfragmentary motion in the order of 500 μm and artificial micromovement during the fi rst month of treatment resulted in significantly shorter healing time. Flexible fi xation promotes micromotion, which produces exuberant callus clearly visible on x-rays, while rigid fi xation diminishes this. Herein lies the relevance of mechanobiology to osteosynthesis. 2.1.3

Phase of fracture consolidation

When tissue strain is below 2%, all calcified cartilage will become bone provided there are adequate osteogenic factors. This process is easily monitored by x-rays, in which the fracture gap or lucency will slowly disappear with more mineralization. There is also a reduction in osteopenia (porosity) concomitant with the reduction of hypervascularity at 12 weeks. Consolidation begins as early as 6 weeks and may last up to 6 months. Strain of between 5% and 20% will result in limited ossification and persistence of fibrous tissue, leading to fibrous nonunion. Mechanically speaking, an implant should hold the fracture at least until the consolidation phase is complete. 2.1.4

Phase of bone remodeling

Further maturation of bone includes the realignment of the 3-D helical bone structure with lines of stress applied to the bone according to Wolff’s Law. This fi nal process of fracture healing begins at about 3 months and may take up to a year to complete. Cancellous bone consolidates and remodels only to the trabecular phase, which takes about half the time of cortical bone that must remodel into a complex Haversian structure through a

slower process. Implants can be safely removed once the remodeling process is evident on x-rays showing corticomedullary differentiation (recanalization) at the site of fracture. 2.2

Biomechanics of fracture callus

Fracture callus of mineralized cartilage forms between bone ends and is called gap callus; along the medullary cavity (medullary callus) and on the outer cortex (periosteal callus) (Fig 2-1). The importance of callus is to provide initial stiffness at the fracture ends so that osteogenesis can occur. The stiffness generated must resist bending and torsional forces. This stiffness is minimal in the early phase and fracture immobilization or internal fi xation is thus employed. If absolute stability is provided by implants, there is no stimulation for the callus process, and direct healing takes place, ie, gap callus healing. In this case, the consolidation process is essentially bypassed by going straight into the remodeling phase. In indirect fracture healing, the weakest callus is gap callus generated between well-reduced fracture ends. As shown in Fig 2-1a–b, medullary callus provides some resistance to bending forces, but it is periosteal or extracortical callus that is most effective in providing the bending and torsional resistance (Fig 2-1c–d). Mechanically speaking, a collar of fracture callus is good, and indicates succesfull indirect healing and should not be regarded as a failure of osteosynthesis.

With intramedullary devices, one is able to see large extracortical callus, while medullary callus is minimal owing to the presence of the nail (Fig 2-2a, Fig 2-3a). With plate osteosynthesis, there is abundant medullary callus. Periosteal callus also forms on the side opposite to the plate, especially on the compression side of the bone (Fig 2-2b, Fig 2-3b).

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2

Mechanobiology

a

b

a

Callus in endosteum

b Fig 2-2a–b a

Callus formation with implants.

The presence of the nail inhibits callus formation in the endosteum.

b c

Periosteal callus is formed on the side opposite to the plate.

Callus in periosteum

a d

Fig 2-1a–d

Callus in both periosteum and endosteum

Callus formation in fractured bones provides bending

rigidity. Abundant callus formation increases bending rigidity.

b Fig 2-3a–b

Canine tibial fracture; callus formation in relation to

implants. a

Note the minimal presence of medullary callus in nailed bone showing abundant periosteal callus at 42, 90, and 120 days (left to right).

b

More medullary callus has formed in fractures which were plated at 42 and 90 days, and which has remodelled after 120 days (left to right).

11

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2.3

Stability in fracture healing

2.3.1

Absolute stability

Absolute stability means absence of motion at fracture site, resulting in nonappearance of fracture callus, especially when the fracture ends are highly compressed without gap. Should there be failure or delay in union, cyclical fatigue of the implant may occur from functional loading of the limb. Fatigue failure may occur at points of weakness within the device such as a screw hole. It is imperative that during the healing process the period of high stress in an implant is kept short, especially in slow healing cortical bone. In cancellous bone, healing occurs at twice the rate of cortical bone so that the implant does not fail from fatigue but may fail from loosening because of differential stiffness between implant and bone, especially in osteoporotic bone.

2.3.2

Relative stability

Relative stability encourages the formation of fracture callus. It is a partnership between an artificial implant and callus. The increasing stiffness and strength of fracture callus unloads stress from the implant, thereby protecting it from failure. In the clinical setting, this is most desirable in diaphyseal fractures. In the application of Wolff’s Law to fracture mechanobiology it may even be more beneficial to have flexible plating, so as to stimulate extracortical callus (Fig 2-4, Fig 2-5). Plates have been thought of as “stress-protecting,” but may also function as “stress-sharing” implants.

Future implants may have built-in variable stiffness.

a

b Fig 2-4a–b a

Plate rigidity and healing type.

Fracture fi xation with a less rigid plate; a fracture gap is still

a

b

c

visible after 7 weeks. The fragment ends have resorbed, and b

periosteal callus has formed.

Fig 2-5a–c

Using a more rigid plate; the fracture has remodelled and less

with solid callus where gap strain is small. No bone grafting was

periosteal callus is present.

performed in this case.

Principle of leaving large fracture gaps which rapidly fill

12

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2

Mechanobiology

Absolute and relative stability can be combined in a single bone, as in an intraarticular fracture with metaphyseal and diaphyseal extension. The articular joint block is rigidly fi xed with lag screws and no gap strain, while the metaphyseal and shaft parts are less rigidly fi xed with fewer screws in a long plate (Fig 2-6).

3

3.1

butterfly bone fragment. However, it may not make a significant difference to the overall fi xation stability. The stress in the plate, screws, and bone is dependent on the fracture gap. Stress in the plate and screws at the fracture site will be higher when the fracture gap is big than when the fracture gap is small. Great care should thus be taken to minimize fatigue and wear of plates and screws in MIPO.

The application of gap strain theory

Fracture gap strain

The surfaces of fractured bone fragments are irregular and exact apposition between bone fragments as well as stability may be difficult to achieve. Interfragmentary strain theory— also called “gap strain theory” by Perren—explains different types of tissue formation based on the strain at the fracture gap. If the fracture gap is very small, then for an applied load at the fracture site, the strain (elongation/gap width) is large. Thus granulation tissue—which can accommodate 100% strain—is formed at a small fracture gap. For similar loading, a larger fracture gap permits cartilage formation, as the strain is smaller. This may be a reason for fracture ends to resorb naturally, thereby forming a larger initial gap. Fibrogenic tissue contributes to a reduction in strain at the fracture site. This further diminishes interfragmentary strain and will allow cartilage and eventual bone formation. Interfragmentary strain theory implies that a larger gap may be more conducive to bone formation than a smaller gap.

While end-to-end bony apposition is advocated, side-to-side gaps need not be closed, allowing micromotion to establish callus between the butterfly and the main shaft fragments (Fig 2-5). Interfragmentary compression of these fragments increases gap strain unfavorably and may also devitalize the

a Fig 2-6a–c

b

c

Combination of absolute stability at the joint block

and relative stability at the diaphysis in a complex fracture configuration.

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3.2

Osteosynthesis with plate fixation

Irrespective of the type of fracture fi xation, the main purpose of using a fracture implant is as follows: Transfer the loads (tension, bending, and torsion) from one end of a broken bone to another. Provide initial stable fi xation with a compressive strain of the order of not more than 2% at the fractured site to promote bone healing. Allow as much of the surrounding bone to be stressed under normal loading during the healing process, so as to prevent “disuse” osteoporosis of the bone. The factors governing the success of fracture healing are: The degree of contact between the bone fragments Alignment of the bone fragments Controlled micromovement at the fracture site Good blood supply at the fracture site Other parameters such as age, health, and nutritional status of the patient Nonoccurrence of implant failure

Problems with plate fi xation include: Loosening of screws Local effects on vascularity of the cortex beneath the plate Implant failure from quality issues Too much or too little hardware

4

4.1

Mechanobiology in fracture fixation

Important aspects of the plate

The major factors affecting the bone–plate fi xation are (Fig 2-7): Geometry and material of plate Placement of plate relative to loading forces Bone–screw interface Induction of compressive stress between bone fragments Quality of bone Surface area of bone–plate interface Type, number, direction, and location of screws Based on these factors, a surgeon can decide whether to achieve rigid fi xation or flexible fi xation.

6

Fig 2-7

1

7

2 4 Factors affecting the bone–plate fi xation:

3

5

1

Geometry and material of plate

5

Quality of bone

2

Placement of plate relative to loading forces

6

Surface area of bone–plate interface

3

Bone–screw interface

7

Type, number, direction, and location of screws

4

Induction of compressive stress between bone fragments

14

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2

Mechanobiology

Although the nature of in vivo loading is complex, it can be broadly categorized as axial (compression and tension), bending, and torsion. Bending alone is considered in most studies on fracture fi xation, because bending will induce both tension and compression stress in the bone, and tend to open the fracture gap, leading to instability of the fracture fi xation. Bending moment is caused by eccentric forces on long curved bones and by antagonistic muscle action during movement at the joints. The role of the plate is to absorb the tensile forces at the fracture while compressive forces are generated at the surface opposite to the surface under tension. Significant torsional forces are added to bending forces, especially in the femur and humerus.

screw is designed to lock into the plate and this internal fi xator acts as a single construct. Bending or contouring the plate causes divergence or convergence of adjacent screws, which then improve the bone-holding power by resisting screw pullout.

A weak portion of the plate, eg, an unfi lled screw hole, should not be placed exactly over the fracture gap so as to avoid “stressriser” plate failure.

With more screws, the fi xation is more rigid and there is less tendency of failure due to screw pull-out.

4.2

Important aspects of screws

4.2.1

Screw design

The bone screw is a critical implant–bone interface and its design has been studied extensively. Standard screws are essentially of two types—the cortex screw and the cancellous bone screw—to accommodate the type of bone and the required holding power. The theory of thread shape factor (TSF) has been outlined by Chapman and depends on the variables shown in Fig 2-8 . It is assumed that these data are constant when analyzing plate function, but it is clear that screw integrity varies with many factors such as bone quality, screw design, insertion technique, and even thermal necrosis and resorption of bone associated with drilling. The use of sharp drill bits and fluid irrigation reduce thermal effects on drill holes. With fewer screws used in MIPO, every screw should be placed with greater attention to technique. A new third type of screw is the locking head screw (LHS) (Fig 2-12b) in which the TSF does not determine bone-holding power because the

4.2.2

Number of screws in a plate

In plate fi xation using the tension band technique, the screw farthest from the fracture site is loaded more than the screws near the fracture site during bending. Keeping the length of the plate constant, with the increase in number of screws there is a decrease in the magnitude of load on each screw (Fig 2-9).

However, more screws weaken the bone. Hence we need to strike a balance with the appropriate number of screws. Stoffel found that there is no significant improvement in fracture fi xation with a 12-hole locking compression plate (LCP) beyond three screws on either side of a fracture against bending, and four screws per fragment against torsion.

Length

Pitch

Core diameter Thread diameter

Fig 2-8

Different variables defining the screw design.

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4.2.3

Influence of screw placement relative to the fracture site

The screws enable the plate to conform to the bone surface. Minimizing the distance between the nearest screws on either side of the bone fragments (also called working length) increases stiffness at the fracture (ie, reducing gap motion) (Fig | Anim 2-10a). The plate stress within this short working length is also higher. When the innermost screws are further away from the fracture site, the working length of the plate is greater, allowing bone deformation and gap opening (Fig | Anim 2-10b), but there is better stress distribution in the plate. The farthest screws determine the effective usage of plate length and contribute to fracture gap stability (Fig 2-10c–d).

a

b

c Fig 2-9a–c

More screws in one plate decrease the magnitude of

force (red arrows) in each screw and therefore reduce the risk of pull-out. Working length Animation

c

a

Effective usage of plate length Working length

b

d

Fig | Anim 2-10a–d

Effective usage of plate length

Influence of screw placement relative to the

fracture site. a

Minimizing the distance between the nearest screws on either side of the bone fragments (also called working length)

c–d The farthest screws determine the effective usage of plate length and contribute to fracture gap stability.

increases stiffness at the fracture (ie, reducing gap motion). b

Therefore, the stress within the longer working plate length is lower.

16

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2

Mechanobiology

Long plates not only help in overall fracture stability, but also reduce internal plate stress with less likelihood of fatigue failure (Fig | Anim 2-11). Analysis of the influence of the distance between the screws and the location of the nearest screws from the fracture site on the forces in the screws and the fracture gap have confi rmed this. It is also important to balance the spacing between the screws with respect to overall plate length on either side of the fracture. Differential stiffness may lead to one-sided fi xation failure, especially in the softer metaphyseal bone.

For plates extending from diaphysis to epiphysis, fewer screws are required in the former and more screws needed in the latter to achieve stiffness-balanced fi xation. 4.3

Bone–plate interface

High frictional compressive forces will develop between conventional plates and the bone due to tightening of screws (Fig 2-12a). This frictional force prevents the sliding motion

Animation

a

b

Fig | Anim 2-11a–b

Stress variation on a long plate due to the distance between screws.

b

a Fig 2-12a–b a

Typical force distribution of a plate osteosynthesis without

b

Typical force distribution of a locking internal fixator (LIF)

angular stability: The screw tightening moment leads to surface

osteosynthesis with angular stability: This configuration is

pressure between the plate and bone. The friction thus created

statically secure with only monocortical fixation since the so-

in the plate–bone contact zone stabilizes the bone fragment in

called locking head screw (LHS) is anchored in a mechanically

relation to the load carrier. This system only becomes statically

stable manner in the load carrier, perpendicular to the plate

secure after bicortical screw fixation.

body. Such systems act more like fixators than plates.

17

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between plate and bone during loading and helps to reduce shear forces on screws at the bone–plate interface. However, compressive forces will damage the blood supply in the bone underneath the plate. The bone underneath the plate may become weakened due to temporary porosity resulting from internal remodeling. The factors affecting the amount of friction are the surface roughness of the plate and compressive force applied during tightening of the screws.

bending, the helical plate protects the fracture by not allowing the callus to be under tension, while away from the fracture site the helical plate allows the bone to bear both tensile and compressive stress generated due to bending (Fig 2-14b). Thus, the bone away from fracture is not shielded from stress due to the helical shape of the plate. Under axial loading, the fracture gap closure is quite uniform, unlike that with the conventional straight plate (Fig 2-14c).

The LCP (Fig 2-12b) avoids damage to the periosteum as the plate stands off from bone. Force transfer is purely through screws and not by contact between plate and bone. The periosteum can be preserved and cortex thinning is reduced. However, shear forces at the bone–screw and screw–plate interfaces are high. With titanium versions, interdigitation may occur between screw head and the hole. Removal of the implant may then be very difficult or even impossible.

However, in all loading conditions the helical plate is highly stressed at the screw holes near the fracture site. The screws nearest to the fracture site are concomitantly high loaded compared with the other screws in compression and torsion, while in the case of bending, stress is distributed more toward

4.4

Helical plating

The concept of a helical plate was fi rst introduced by Fernandez. In this idea one has the freedom of selecting any entry point for minimally invasive surgery (MIS). In addition to the biomechanical properties discussed in detail below, this plate offers distinct clinical advantage; for instance helical contouring takes into account the anatomy of the humerus with respect to the radial nerve (Fig 2-13). We have studied the efficacy of a 180º helical plate by using fi nite element method (FEM) analysis on long bones subjected to torsional, bending, and axial loads (Fig 2-14). In the FEM analysis, the helical plate was more effective in bearing the tensile force (diagonal to the bone axis) generated during torsional loading thus providing good stability at the fracture site. During torsion, the bone is weakest in tension and a helical plate protects the bone in the same direction (Fig 2-14a). In

a Fig 2-13a–b

b The helical contouring of this plate takes into account

the anatomy of the humerus with respect to the radial nerve.

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2

Mechanobiology

the farther screws. Hence, in general helical plates will provide good fracture stability in torsion and reasonable stability in bending, while reducing stress shielding of the bone.

a

4.5

Choosing relative stability in MIPO

Relative stability is more appropriate for MIPO, especially in the comminuted diaphysis. Relative stability is all about providing sufficient stability at the fracture site to the extent that postoperative mobilization of the extremity is possible and flexible enough to allow some micromotion at fracture site, so as to promote rapid and reliable bone healing by formation of callus. In other words, the surgeon does not need to rely on the plate for a prolonged period, with the added advantage that the effects of cortical necrosis and stress shielding are reduced. Another advantage of relative stability is that accurate apposition of the fragments is not necessary and external callus is expected to bridge the fracture gap given the correct mechanobiological situation. Blood supply to the bone is also less disturbed by avoiding exposure of fracture site.

b

5

c Low stress High stress

Fig 2-14a–c

During torsion, the bone is weakest in tension and a helical plate protects the bone in the same direction.

b

In bending, the helical plate allows the bone to bear both tensile and compressive stress.

c

When there is indication for osteosynthesis of a fracture, the fi rst decision to make is whether absolute or relative stability is desired. This is critical especially when dealing with complex and segmental fractures involving the joint, metaphysis, and diaphysis.

Efficacy of a helical plate with regard to torsional (a)

bending (b), and axial (c) loads. a

Biomechanical considerations in preoperative planning

Under axial loading, the fracture gap closure is quite uniform, unlike that of the conventional straight plate.

Absolute stability is best indicated in articular fractures and can be achieved by interfragmentary compression using the appropriate lag screw technique. Added stability can be achieved by buttress plating to prevent shear forces during joint motion or loading. Simple shaft fractures may also be treated by absolute stability, but require direct reduction, as in the forearm.

19

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Relative stability is best applied to multifragmentary fractures, especially in the metaphysis and diaphysis. For relative stability, it is important to select the appropriate plate in terms of shape and strength. It is important that the shape conforms to the anatomical surface so that implant and bone can act as a single construct. Strength is critical to prevent premature implant failure, as in these situations the shared support expected from bone may be inadequate in the early period of healing. In general broad plates 4.5 (with 4.5 mm screws) are used in the femur, narrow plates 4.5 in the humerus and tibia, and plates with 3.5 mm screws in the radius and ulna or fibula. The implant should be placed so as to provide balanced stability on both sides of the fracture gap. If one fragment is more rigidly fi xed to the plate, it will have a higher stiffness than the other fragment, thus causing higher motion amplitude to occur in the fracture gap. If the other fragment is not as rigidly “captured” by the implant, then stress at the screw– bone interface will result in loosening of the unlocked screws. This is an important concept in locked screw–plate systems, which should not have all locked screws in the epi-/metaphysis while having none in the diaphysis.

6

Common errors

MIS has often been equated with an arbitrarily small number of screws as well as the length of the incisions. The reality is that the exposure is just sufficient to insert the plate and target the desired screw holes. The fracture itself should not be exposed, but reduced by indirect methods, with the option of a “mini-open” incision to directly manipulate the displaced fracture fragment where indirect means fail.

Common errors: Filling in as many screws as possible, causing excessive stiffness. Using too short a plate; the plate should span from one metaphysis to the other. Using extremely long plates on curved bones; either the proximal or distal screws may miss engaging the bone. Not centering the plate with respect to the fracture site, ie, having one limb longer than the other. Leaving a single unfi lled screw hole opposite a small bone defect. Using LHS on one side of the fracture and standard screws on the other side in an LCP.

7

Summary

Every surgeon should know the biology of fracture healing so as to anticipate the outcome of planned treatment. The timing and method of intervention are crucial if one respects the important role of soft tissue in bone healing. Damage to tissues in the injury zone will be the major factor for the occurrence of complications such as bone devitalization, infection, delayed union, and nonunion. Mechanobiology will play a key role in fracture surgery as MIS approaches are developed. With MIPO techniques, fracture apposition may be limited to achieving axial and rotational alignment and maintenance of bone length. With fracture comminution or bone loss, the choice of implant will be of utmost importance if secondary surgery such as bone grafting and replating are to be avoided. A good surgeon can actually dial-in the amount of stability required so as to manipulate a desired fracture healing pattern. In future, preoperative planning will likely be performed using parametric mechanical data instead of images.

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2

Mechanobiology

Angular stable implants may become standard as angular stability provides a way to control and limit excessive interfragmentary motion. However, stress will increase within the implant and failure can still occur. As with all trauma surgery, proper knowledge and training, preoperative planning, technically well-executed surgery, comprehensive rehabilitation, and timely follow-up will result in a predictably good outcome even in the most difficult of fractures.

Perren SM (1979) Physical and biological aspects of fracture healing with special reference to internal fi xation. Clin Orthop Relat Res; Jan–Feb(138):175–196. Rand JA, An KN, Chao EY, et al (1981) A comparison of the effect of open intramedullary nailing and compression-plate fi xation on fracture site blood flow and fracture union. J Bone Joint Surg [Am]; 63(3):427–442. Stoffel K, Dieter U, Stachowiak G, et al (2003) Biomechanical testing of the LCP—how can stability in locked internal fi xators be controlled? Injury; 34 Suppl 2:11–19.

8

Suggested reading

Albright JA, Johnson TR, Saha S (1978) Principles of internal fi xation. Ghista DN, Roof R (eds), Orthopaedic Mechanics: Procedures and Devices. London: Academic Press, 123–229. Chapman JR, Harrington RM, Lee KM, et al (1996) Factors affecting the pullout strength of cancellous bone screws. J Biomech Eng; 118:391–398. Day SM, Ostrum RF, Chao YS, et al (2000) Bone injury, regeneration and repair. Buckwalter JA, Einhorn TA, Simon SR (eds) Orthopaedic Basic Science: Biology and Biomechanics of the Musculoskeletal System, 2nd ed. Illinois: American Academy of Orthopaedic Surgeons. Fernandez Dell’Oca AA (2002) The principle of helical implants: Unusual ideas worth considering. Injury; 33 Suppl 1:SA1–27. Review. Goodship AE, Kenwright J (1985) The influence of induced micromovement upon the healing of experimental tibial fractures. J Bone Joint Surg [Br.]; 67(4): 650–655. John AH, Edward JC, Wilson CH (1992) Biomechanics of fractures. Browner BD, Jupiter JB, Levine AM, Trafton PG (eds), Skeletal Trauma: Fractures, Dislocations, Ligamentous Injuries. Philadephia: Saunders, 95–125. Johnson KD, Tencer AF (1994) Biomechanics in Orthopaedic Trauma. Bone Fracture and Fixation. London: Martin Dunitz. Laurence M, Freeman MA, Swanson SA (1969) Engineering considerations in the internal fi xation of fractures of the tibial shaft. J Bone Joint Surg [Br]; 51(4):754–768.

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3

Instruments

1

Introduction

23

2

Instruments to aid fracture reduction

23

2.1

Reduction handles

23

2.2

External fixators

25

2.3

Large distractor

25

2.4

Collinear reduction clamps

25

2.5

Periarticular reduction forceps

25

3

Instruments to aid plate insertion and fixation 26

3.1

Tunneler

26

3.2

Soft tissue retractor

26

3.3

Plate holder

26

3.4

Plate pusher

28

3.5

Sleeves to aid percutaneous screw fixation

28

3.6

Tension device

30

4

Instruments for plate removal

31

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Author

3 1

Suthorn BAVONRATANAVECH

Instruments Creation of a submuscular, extraperiosteal tunnel for the plate Introduction of the plate Fixation of the two ends of the plate through the original incisions Checking the quality of reduction, length, axial alignment, and rotation Completion of the fi xation with screws introduced through stab incisions making adjustments to the fracture reduction if necessary Final check on fracture reduction and implant position Wound closure

Introduction

Minimally invasive plate osteosynthesis (MIPO), in contrast to conventional open reduction and internal fi xation using plates, is performed without exposure of the fracture site, the aim being to preserve biology with minimal disruption of softtissue attachments and vascular supply. In order to accomplish this, the fractures are reduced by indirect means and the implants introduced from a site remote from the fractures. To facilitate this minimally invasive method of fracture reduction and fi xation, special instruments are required. Instrument systems are still evolving but those introduced so far can be grouped according to the functions that they perform as follows: Instruments to aid fracture reduction Instruments to aid plate insertion and fi xation Instruments for plate removal Some of these instruments are commercially available, others were fabricated according to the needs of the surgeon. As MIPO evolves, instruments will be refi ned to make the procedure easier and more reproducible in the hands of most surgeons. In order to have a better understanding of the functions and applications of the various instruments, it is necessary to be familiar with the basic steps of a MIPO procedure, which is usually performed in the following sequence: Indirect fracture reduction Temporary fi xation to hold the reduction if necessary Skin incisions remote from the fracture site, corresponding to the ends of the plate, one on each side of the fracture

2

2.1

Instruments to aid fracture reduction

Reduction handles

These can be used for minimally invasive fracture reduction. As they can be used with self-drilling threaded rods or guide wires, application is easy. They can be connected with clamps and rods to function as external fi xators for temporary intraoperative fracture stabilization. Available in two different sizes for use with large and small fragment implants, they come with toothed or rounded tips. The toothed tip provides rotational stability and can be used with considerable force during fracture manipulation and reduction. The rounded tip is used with the threaded guide wire when a lower force is required during fracture reduction. When using these reduction handles, it is important to ensure that their locations would not interfere with subsequent plate application (Fig 3-1).

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a

b

Fig 3-1a–d a

Screw the self-tapping threaded rod through the drill sleeve.

b

Attach the reduction handle to the threaded rod and push close to the bone. Then tighten the adjusting screw. The second reduction handle is applied in the same way.

c c

Apply combination clamps and rod but without tightening the nuts. Reduce the fracture under fluoroscopic guidance.

d d

After completing reduction, tighten the nuts of the combination clamps to hold the fracture reduction temporarily.

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3

2.2

Instruments

External fixators

tubes are locked in position with a middle tube and two tubeto-tube clamps that have been preassembled (Fig 3-2).

The tubular external fi xator system, together with Schanz screws, can be used in the same manner as the reduction handles for indirect fracture reduction and temporary fracture fi xation. In order to reduce radiation exposure of the surgeon’s hands during the maneuvers to achieve fracture reduction, manipulation of the Schanz screws can be done through two long tubes connected to the Schanz screws by clamps. Once satisfactory fracture reduction is obtained, the ends of both

2.3

Large distractor

The function of the large distractor is essentially the same as that of the external fi xator, except that the distractor can be used to distract or compress the fracture zone by means of tightening a nut (Fig 3-3). 2.4

Collinear reduction clamps

These allow minimally invasive fracture reduction through a collinear closing mechanism with modular arms for the reduction of long-bone, pelvic, and articular fractures. Different positions of the arms are possible and they permit a continuous application of force. There are three types of modular arm: the pelvic arm, percutaneous arm, and Hohmann-style arm. These arms are cannulated to allow the insertion of K-wires (Fig 3-4). 2.5

Periarticular reduction forceps

These come with spherical tips and are useful for direct or percutaneous application to hold large articular fracture fragments (Chapter 7 Reduction technique: Fig 7-1).

a Fig 3-2a–b

b Modular external fi xator used for indirect fracture

reduction. a

Two pins are inserted in each main fragment outside the zone of injury. They are fi xed to a tube by universal clamps, and function as two handles for indirect reduction.

b

After reduction the two tubes are united by a third tube and two

Fig 3-3

tube-to-tube clamps.

stabilization.

Large distractor used for temporary intraoperative fracture

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3

3.1

Instruments to aid plate insertion and fixation

Tunneler

The tunneler is used to prepare a pathway for the introduction of the plate in a submuscular extraperiosteal plane. It consists of a handle and a blade. The handle has a vertical and a horizontal arm, the latter serving as a directional guide during the blade’s introduction. The blade is 30 cm long and marked with 5 cm graduations which serve as a guide to the length of the plate to be used. There is a hole at the tip of the blade which allows a suture to be tied to one end of the selected plate so that as the tunneler is withdrawn, it pulls the plate along with it into the tunnel created (Fig 3-5). When using the tunneler, it is important to avoid introducing it repeatedly or pushing it back and forth too many times as this will strip the periosteum and damage the soft tissue.

a

3.2

Soft-tissue retractor

The soft-tissue retractor functions as a tunneling instrument to prepare the pathway for plate insertion. It has an extendible blade which can be rotated through 180° allowing any blade angle to be selected (Fig 3-6). 3.3 b

Fig 3-4a–b

Collinear reduction clamps.

a

Reduction of the femoral shaft using the Hohmann-style arm.

b

Reduction of the femoral condyle using the percutaneous arm.

Plate holder

The plate selected for the fracture fi xation can itself be used to create the submuscular tunnel by attaching a plate holder to one end of the plate. The plate holder is also used to hold the plate for percutaneous insertion and allows optimal guidance and monitoring of the plate under the soft-tissue mantle (Fig 3-7a). It can be used with the broad and narrow limited contact dynamic compression plate (LC-DCP) and locking compresion plate (LCP).

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3

Instruments

Fig 3-6

The soft-tissue retractor with an asym-

metric extendible blade facilitates percutaneous

a

plate insertion.

a

b

c

b

Fig 3-5a–c

Fig 3-7a–b

This tunneler has a blade length of 30 cm and a hole at the tip to

a

allow insertion of a suture to pull the plate into position as it is withdrawn.

The plate holder allows optimal guidance and monitoring of the plate under the soft-tissue mantle.

b

An LCP can be introduced using a special handle with a threaded end which is screwed into the plate hole.

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In the case of the LCP a special handle with a threaded end, (Fig 3-7b) or the threaded drill guide, can also be fi xed to one end of the plate to act as a handle for plate introduction. 3.4

Plate pusher

The function of the pusher is to temporarily push the plate against the bony cortex. It has a tip similar to a cortex screw complete with a head that can fit into the plate hole and so can be used to temporarily fi x the plate to the bone after the plate has been properly positioned. It has a detachable handle (Fig 3-8). If such an instrument is not available, a standard cortex screw introduced through one cortex at one end of the plate will serve the same function.

a

b

3.5

Sleeves to aid percutaneous screw fixation

Screws can be inserted into either end of the plate through the original incisions made to insert the plate. To insert screws into the central portion of the plate, the position of the screw holes can be located by placing a plate of similar length over the skin to match the position of the inserted plate and marking the position of the screw holes on the skin. Stab incisions are then made and the underlying muscles are split with a hemostat until the plate hole is reached. In the case of an LCP, a threaded drill guide is screwed onto the threaded half of the combination hole if a locking head screw (LHS) is to be used. If a standard screw (cortex screw, cancellous bone screw) is to be inserted, a long sleeve is required to protect the soft tissue. The long 5.0/3.5 mm sleeve with a trocar from the external fi xator set can be used for this purpose. In the case of conventional plates, a special sleeve with a balltipped trocar that fits into the dynamic compression hole can be used (Fig 3-9a). The end of this special sleeve has two teeth that prevent it from slipping out of position once it sits in the plate hole. When the ball-tipped trocar, together with the special sleeve, sits correctly in the plate hole, the trocar is replaced by a drill sleeve. The hole is drilled and the drill sleeve is removed (Fig 3-9b). If desired, the depth is measured using the special, long depth gauge from the external fi xator set. A tap sleeve is inserted next. Tapping is then carried out. The tap sleeve is removed and the screw inserted through the special sleeve (Fig 3-9c).

Fig 3-8a–b a

The pusher, which has a tip similar to a cortex screw, can be used to fi x the plate onto the bone.

b

The detachable handle from the pusher can be used to fi x a Schanz screw which can then be used as a manipulator or reduction tool.

A soft-tissue spreader is also available for the minimally invasive, noninjurious insertion and removal of screws. This is a modular forceps system that consists of a handle operable with a single hand, mountable soft-tissue retractors with different blade lengths, and adapted trocars. The soft-tissue retractors

28

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3

Fig 3-9a–c

a

b

Instruments

The special sleeve for percutaneous insertion of standard screws in conventional plates—the steps in its application:

Step 1: After a stab incision is made, the outer sleeve

fi t into the plate hole. Once the plate hole is identi-

with the trocar is passed through the muscle layer.

fied, the outer sleeve fi ts into the plate hole with its

The trocar has a ball tip that has been designed to

teeth at the tip. The trocar is then removed.

Step 2–3: The drill sleeve is inserted next through

c

Step 4: After drilling and tapping, the screw is in-

the outer sleeve and removed after drilling. The tap

serted through the sleeve with a screwdriver and

sleeve is then inserted through the outer sleeve and

screwed into the plate hole.

removed after tapping. It is necessary to have a long tap in order to pass through the sleeve.

29

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together with the trocar are inserted through a small incision made over the selected plate hole. Once the trocar locates the plate hole, the retractors are spread open and the trocar removed to expose the plate hole.

3.6

Tension device

The tension device can be used either as a lengthener or a compressor depending on the direction of its hook in relation to the end of the plate (Fig 3-10). Another method to gain length is to use a spreader between the end of the plate and a screw inserted a short distance away, the so-called “push–pull” technique (Fig 3-11).

Animation

a Fig | Anim 3-10a–c a

b

c

Use of the tension device with a condylar plate.

Introduction of the condylar plate 95º, insertion of screw proximally, and temporary monocortical screw fi xation distally to push the plate to the bone.

b

Use of the tension device to distract the fracture and to allow fracture reduction proximally. The monocortically fi xed distal screw must be removed before distraction can take place.

c

Use of the tension device for interfragmentary compression once the fracture has been reduced.

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3

Instruments

a

b

Fig 3-11a–b a

Push–pull technique.

The bone spreader, placed between the end of a plate and an

b

Thereafter, and using the same independent screw, axial com-

independent screw, can be used to distract the fracture. Care

pression can be obtained by pulling the plate end toward the

should be taken to minimize soft-tissue stripping when applying

screw with a small Verbrugge forceps.

the bone holding forceps.

4

Instruments for plate removal

Plate removal is not performed routinely but, when indicated, can be removed by minimally invasive means. A MIPO chisel is available for callus removal (Fig 3-12).

conical extraction screw with a left-handed thread is available that can be inserted into the screw head using a T-handle with quick coupling and loosening the LHS by turning the conical extraction screw in an anticlockwise direction.

To remove an LCP that has been fi xed with LHS, it is necessary to fi rst unlock all the screws before removing them defi nitively in a second step; otherwise the plate may rotate while the last screw is being removed, resulting in damage to the surrounding soft tissue. A screwdriver is used to remove the screws. However, this is not always possible if the recess of the LHS is damaged or the screw is stuck in the plate. Under such circumstances, a

Fig 3-12

Chisel for callus and plate removal.

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4

Implants

1

Introduction

33

2

Internal fixators

33

3

Conventional plates and standard screws

37

4

Bridging plates

38

5

Implants for MIPO

38

6

Guidelines for use of implants for MIPO

38

6.1

Locking compression plates—LCP

38

6.2

Conventional plates—DCP and LC-DCP

41

6.3

Fixed angle implants

41

6.4

Indications for insertion of locking head screws in an LCP

6.5

41

Indications for insertion of standard screws in an LCP

42

7

Choice of implants for different bone segments 42

7.1

Diaphyseal fractures

42

7.2

Metaphyseal fractures

43

7.3

Articular fractures with extension into the

8

metaphysis/diaphysis

44

Suggested reading

45

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Author

4 1

Frankie KL LEUNG

Implants Introduction

2

Minimally invasive plate osteosynthesis (MIPO) is a modern concept of fracture fi xation, the aim of which is to preserve biology at the fracture site so as to maximize the healing potential of the injured bone and soft tissue, and facilitate rapid pain-free recovery of function. This can best be achieved by carrying out the procedure without exposure of the fracture and by introducing the plate in a submuscular, extraperiosteal position with minimal disturbance to the vascularity of the bony fragments.

a

Internal fixators

The introduction of the internal fi xator has made MIPO a more practical proposition and widened its scope and range of applications. The internal fi xator is in essence a subcutaneously or submuscularly positioned external fi xator. The unique design feature of the internal fi xator is the locking head screw (LHS)—the screw head has a double conical thread for secure fi xation into a corresponding conical thread in the plate hole. This feature imparts a degree of angular stability to the construct, as the locked screw head can no longer toggle in the plate hole. Also, because the screw head is locked in the plate hole, it does not press the plate against the underlying bone as the screw is tightened, unlike standard screws such as cortex or cancellous bone screws (Fig 4-1).

b

Fig 4-1a–b a

No angular stability with standard screws. As there is no stable connection between the screw head and the screw hole, individual screws can toggle within their screw holes, resulting in loosening and failure of fi xation.

b

Angular stability with locking head screws (LHS). The conical and threaded hole in the internal fi xator provides angular stability due to rigid connection with the threaded head of the LHS.

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The internal fi xator thus possesses features that make it suitable for MIPO. These include: LHS which prevent the plate from being pressed against the underlying bone, thus sparing the periosteal blood supply. Since the bone is not pulled against the plate by the LHS as the screws are tightened, there is no loss of primary reduction if the fracture has already been reduced.

Consequently, accurate contouring of the plate is not necessary, a defi nite advantage in MIPO as the bone is not exposed for templating. Angular stability of the construct also prevents secondary loss of reduction of the fracture when placed under load. As the LHS are either self-drilling and self-tapping or only self-tapping, screw application is made easier in the MIPO setting as drilling and/or tapping is no longer required as is the case with the application of standard screws. The fi rst internal fi xator specifically designed for use in MIPO was the less invasive stabilization system (LISS) for the distal femur (Fig 4-2). As the advantages of the LISS became apparent, demand for a more versatile system increased, and this led to the development of the locking compression plate (LCP) with a specially designed combination hole, one half of which is designed as a dynamic compression unit that allows the use of standard screws for interfragmentary or axial compression, while the other half is threaded to allow the application of LHS. Thus the LCP can function as a compression plate or as an internal fi xator when only LHS are used (Fig | Anim 4-3).

a Fig 4-2a–b

b Femoral fracture stabilized with a LISS for the distal

femur, 6 weeks postoperatively; AP (a) and lateral (b) views.

In theory, no contouring of the LCP is necessary when used as an internal fi xator, but in practice, some degree of contouring is usually needed, especially in the epi-metaphyseal segments of the bone. Otherwise the plate may stand proud and become prominent subcutaneously or cause irritation of the adjacent soft tissue. To overcome this problem, specially designed metaphyseal plates were introduced. The special features of this plate are that the juxta-articular end of the plate is thinned out to facilitate contouring and the two distal holes in this thinned area of the plate are angled at 11˚ toward the center of

34

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4

Implants

the plate to allow optimal application of the LHS in the epiphyseal area in order to avoid penetration of the articular surface. A further refi nement of this is the development of anatomically preshaped LCP for use in specific epi-metaphyseal parts of the skeleton. The metaphyseal end of such a plate allows the insertion of a cluster of LHS in a divergent or convergent manner to improve their pull-out strength. Further, no contouring of the plate is usually needed. An added advan-

tage of these anatomical preshaped LCP is that they can be used as an aid for indirect fracture reduction when used with standard screws. These can draw the bone toward the plate and thus effect an adaptation of the bony fragments to the shape of the plate. Examples of anatomically preshaped LCP are the locking proximal humerus plate (LPHP), LCP distal humerus, LCP distal radius, LCP distal femur, LCP proximal lateral tibia, and LCP distal tibia (Fig 4-4).

Animation

a

b

Fig | Anim 4-3a–c

c

LCP combination hole consists of two parts:

One half of the hole has the design of the dynamic compression unit for standard screws. The other half is conical and threaded to accept the matching thread of the locking head screw (LHS) in order to provide angular stability.

35

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a

b

c

e Fig 4-4a–e a

d

Examples of anatomically preshaped plates include:

LCP distal femur.

b

LCP proximal lateral tibia.

c

LCP distal tibia.

d

Locking proximal humeral plate (LPHP).

e

LCP distal radius.

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4

3

Implants

Conventional plates and standard screws

Although locking compression plates are eminently suited for MIPO, it is also possible to perform MIPO with conventional plates using standard screws. Conventional plates such as the dynamic compression plate (DCP) (Fig 4-5) and limited contact dynamic compression plate (LC-DCP) (Fig 4-6) can be used, and also fi xed angle implants such as condylar plates 95° or dynamic condylar screws (DCS) (Fig 4-7). When using these conventional implants for MIPO, special precautions must be taken to ensure their successful application.

Fig 4-6

The LC-DCP with its structured undersurface for limited

contact between plate and bone and an even distribution of the holes throughout the plate.

a 1

b

c

Fig 4-5a–e

d

Dynamic compression principle.

e

e

The horizontal movement of the head, as it im-

a

The holes of the plate are shaped like an inclined and transverse cylinder.

pacts against the angled side of the hole, results in

b

Like a ball, the screw head slides down the inclined cylinder.

movement of the plate and the fracture fragment

c–d Since the screw head is fi xed to the bone via the screw hole, it can only move vertically, in relation to the bone.

already attached to the plate by the first screw (1). This leads to compression of the fracture.

37

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5

Implants for MIPO

Broadly speaking, MIPO can be performed with the following types of implants: Locking plates, eg, LCP and LISS Conventional plates, eg, straight plates, such as DCP and LC-DCP, and fi xed angle implants, such as condylar plates 95º or DCS

6

a

b

Fig 4-7a–b a b

4

MIPO in proximal femur using a condylar plate 95°. MIPO in distal femur using a DCS.

Bridging plates

Irrespective of whether a locking compression or a conventional plate is used in MIPO, the plate is generally applied in the bridging mode, especially when used for complex fractures. This requires relatively long plates, and stress concentration within the plate should be avoided by placing the screws one or two screw holes away from the fracture zone and spacing out the rest of the screws within the plate. This mode of fracture fi xation provides relative stability and imparts upon the construct a certain degree of flexibility. This promotes fracture healing by callus formation, which in effect is faster and more reliable than primary bone healing. This is particularly important when dealing with multifragmentary fractures.

Guidelines for use of implants for MIPO

The following are some general guidelines when using these implants for MIPO: 6.1

Locking compression plates—LCP

Whenever possible, the fracture is fi rst reduced by indirect methods. If necessary, the reduction is then maintained using distractors or external fi xators. If a well-contoured or anatomically preshaped plate is used, the implant can be used as a reduction aid when used with standard screws (as described earlier). If the compression function of the LCP is to be used, for example in simple transverse fractures, accurate contouring of the plate is fi rst performed; axial compression can then be carried out using standard screws in the dynamic compression unit of the combination holes (Fig 4-5). It is important to note that the LCP combination holes are arranged asymmetrically on the plate. This asymmetry allows axial dynamic compression to be exerted unidirectionally. After axial compression is exerted by the standard screws, additional LHS can then be inserted (Fig 4-8).

38

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4

Implants

If it is desired to apply interfragmentary compression in simple oblique or spiral fractures, this should fi rst be accomplished using standard screws as lag screws before the application of LHS. To insert standard screws, the universal drill guide is used. The screw holes are predrilled, either neutrally or eccentrically, depending on the intended function of the screw. The depth of the screw hole is then measured and tapped, and the appropriate standard screw inserted. If contouring of the plate is necessary, it should be performed using the appropriate bending instruments. Bending should be done between the combination holes and not through the holes as this may cause deformation of the holes and result in difficulty in the subsequent insertion of LHS. One way of preventing this deformation is to insert a threaded drill sleeve or an LHS into the threaded part of the combination hole before carrying out the bending. If desired, an LCP spacer may be screwed into the plate prior to its insertion. The spacer ensures a gap of 2 mm between the plate and underlying cortex, thus minimizing plate–bone contact and preserving periosteal circulation. This spacer can be removed after insertion of the LHS.

a

Skin incisions are made, corresponding in position to the ends of the plate. A tunneler may be used to create a submuscular extraperiosteal tunnel for the plate. The plate is then passed into the tunnel. This can be done in one of several ways. If a tunneler is used, one end of the plate is tied with a suture to the end of the tunneler (Fig 4-9). As the tunneler is withdrawn, the plate is pulled into position. Another way is to fi x one end of the plate with a plate holder or a threaded LCP drill guide which is then used to guide the plate into position along the track created by the tunneler. Once the plate is in place, screw insertion can follow. If the fi rst inserted screw is an LHS, before locking, the other end of the plate should be temporarily stabilized with either a K-wire, a standard screw, a threaded LCP drill guide, or another LHS that is not locked. This is to prevent the plate from rotating (“helicopter effect”) (Fig 4-10) and causing damage to the surrounding soft tissue as the fi rst LHS is tightened and locked. The quality of fracture reduction is checked; if satisfactory, the rest of the LHS are inserted.

b

Fig 4-8a–b

Locking head screws (LHS).

a

Self-tapping.

Fig 4-9

b

Self-drilling, self-tapping.

The plate is attached to the tunneler and pulled back into position.

The tunneler is used to prepare the pathway for the plate.

39

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a

b

Fig 4-10a–b a

Tightening of the first LHS without stabilization of the other end of the plate will cause the “helicopter effect”.

b

Temporary plate stabilization of the opposite end of the plate prevents the plate rotating as the first screw is tightened and locked.

To insert a self-tapping LHS (Fig 4-8a) percutaneously, a threaded LCP drill guide is fi rst introduced through a stab incision in the skin, and then screwed into the threaded portion of the selected combination hole. The drill guide ensures that drilling is done in the correct direction so that the screw is correctly locked to achieve maximal angular stability. The screw hole is then drilled and measured (either by taking the reading from the calibrated drill bit or by using a depth gauge), and the appropriate LHS inserted, fi rst using a power tool with the screwdriver shaft and then performing the fi nal tightening by hand with the torquelimiting screwdriver until clicking occurs. Predrilling and depth measurement are not necessary if a self-drilling, self-tapping LHS is used monocortically (Fig 4-8b). This, however, is only possible in good-quality bone with a thick cortex. Monocortical screw fi xation is also indicated in periprosthetic fractures.

When using an anatomically preshaped LCP, a specially designed guiding block is available which fits into the epiphyseal end of the plate to provide easy and accurate mounting of the threaded LCP drill guide. This ensures that drilling takes place in the correct direction. After predrilling and following removal of the threaded LCP drill guide, the appropriate LHS can be inserted without removing the guiding block, to ensure that the screws are inserted in the correct direction. If necessary, a certain amount of indirect reduction of the fracture can be achieved by using a screw holding sleeve to cover the head of the LHS. When the screw is tightened, the underlying bone will be pulled toward the plate. Three well-spaced screws on each side of the fracture should provide adequate stability for fracture healing by callus. If both standard screws and LHS are used in the same construct, the standard screws should be inserted fi rst.

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4

6.2

Implants

Conventional plates—DCP and LC-DCP

Indirect fracture reduction is fi rst carried out using manual traction or with the help of a distractor or external fi xator. If necessary, the distractor or external fi xator can be used to maintain the reduction achieved. The plate itself can be used as an indirect reduction tool. In this situation the plate has to be contoured accurately to the shape of the bone. Standard screws can be used to aid fracture reduction since they pull the bone toward the plate as they are tightened (Fig 4-5). The appropriate skin incisions are made. A submuscular, extraperiosteal tunnel is created and the plate is inserted as described earlier (except that the threaded LCP drill guide cannot be used to hold the plate as in conventional plates there is no combination hole and therefore no thread). The ends of the plate are fi xed with standard screws after drilling, depth measurement, and tapping, using the appropriate sleeves for soft-tissue protection. The proximal end of the plate should preferably be fi xed fi rst, as it is easier to control the position of the distal fracture fragment by manipulation and traction. The reduction is checked after temporary monocortical screw fi xation of the distal fragment. The rest of the screws are then inserted percutaneously. Usually three screws on each side of the fracture would provide adequate stability. The screws should be well spaced and inserted obliquely to obtain a better hold in the bone. When inserting a screw into a deep-seated plate hole, it is useful to tie an absorbable suture to the screw head before screw insertion and leave the free end of the suture outside the wound. The reason for doing this is that sometimes the screw may get dislodged from the tip of the screwdriver during the process of screw insertion. If this happens, the loose screw can be retrieved with the attached suture. After the screw is fully tightened, the end of the suture outside the wound can be cut short.

Standard screws can be inserted as lag screws to enhance the stability of the fi xation. During plate contouring, the plate can be converted to a wave plate with a curved central portion directed away from the bone. This will help preserve the periosteal blood supply in the fracture zone and promote faster fracture healing with callus formation. Another advantage of the wave plate is that it helps to reduce the risk of mechanical failure of the plate as the stress is distributed over a proportionately longer section of the plate. 6.3

Fixed angle implants

Fixed angle implants such as the condylar plate 95º or the DCS can also be used in MIPO for fractures of the proximal and distal femur. Since the sagittal alignment of the condylar plate has to be determined during the insertion of the seating chisel, it is technically easier to use the DCS, as the sagittal alignment can be adjusted by rotating the condylar screw. It is also more modular in application and easier to insert via a small incision. 6.4

Indications for insertion of locking head screws in an LCP

Osteoporotic fractures Periprosthetic fractures, which are also an indication for monocortical application of self-drilling and self-tapping screws Metaphyseal and periarticular fractures

41

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6.5

Indications for insertion of standard screws in an LCP

When interfragmentary or axial dynamic compression has to be achieved. To assist fracture reduction when a standard screw is used to pull the bone fragment toward the plate. To avoid penetration of the articular surface in periarticular fractures, which may be unavoidable when fi xed angle LHS are used. In such cases, standard screws may be inserted through the dynamic compression unit of the combination hole, parallel to the articular surface.

a

7

Choice of implants for different bone segments

Once the concepts of LHS and standard screws, LCP, and conventional plates (DCP or LC-DCP) are understood, it becomes easier to decide which implant is suited for fractures in the various bone segments. 7.1

Diaphyseal fractures

Either an LCP or a conventional plate can be used. LCP with LHS is more suitable for fractures in osteoporotic bones. In femoral shaft fractures, the normal anterior bowing of the femur must be taken into consideration and the straight plate contoured accordingly (Fig 4-11). Where the end of the plate extends into the metaphyseal area, either proximally or distally, the plate has to be contoured to match the surface of the bone (Fig 4-12).

b

c

d Fig 4-11a–d a–c Sagittal curve of the femur must be considered when using a straight plate. Due to the normal anterior bowing of the femur,

Fig 4-12

When the plate has to extend to proximal or distal

metaphysis, precontouring of the plate should be done.

there is a risk of an eccentric plate position at either end. d

A special sagittally bent LCP, 16 holes is available and can be used to maintain the anterior bowing of the femur.

42

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4

7.2

Implants

Metaphyseal fractures

The metaphyseal LCP is suitable. As the plate is straight, contouring is needed. These plates have a thinner section at one end and a thicker portion at the other end. The thinner section of such plates is designed for easier contouring and will be less prone to cause soft-tissue irritation. The thicker section is designed for application in the diaphysis (Fig 4-13). If there is a risk that the distal LHS may penetrate the joint surface because of their fi xed angle, the bend of the plate may be decreased or altered or the plate may be shifted slightly away from the articular surface to avoid the problem. Alternatively, standard screws can be inserted into the dynamic compression part of the combination hole parallel to the articular surface. Where available, specially designed anatomically preshaped LCP can be used. As these plates are anatomically precontoured, no intraoperative contouring is necessary. The contour of the plate will also serve as a template for realignment of the fracture. In the case of the distal femur LISS, the surgeon must be aware that some patients have excessive anterior bowing in the sagittal plane or varus bowing in the coronal plane. It is important to predict such malalignment between the plate and the bone as this can lead either to erroneous application of the implant with eccentric anchorage of the screw in the bone, or to loss of reduction of the fracture. In the proximal and distal femur, conventional fi xed angle implants such as the condylar plate 95° or the DCS may also be used.

a Fig 4-13a–b

b Straight metaphyseal plate.

The thinner section of the metaphyseal plate is designed for easier contouring and will be less prone to cause soft-tissue irritation. The thicker section is designed for application in the diaphysis. The two sections of the plate are used with LHS with different diameters.

43

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7.3

Articular fractures with extension into the metaphysis/diaphysis

The principles of treatment of intraarticular fractures are anatomical reduction and stable fi xation with lag screws. Reduction can be achieved by arthrotomy or with the aid of an arthroscope or image intensifier. The articular block can then be fi xed to the metaphysis using minimally invasive techniques (Fig 4-14). Any of the implants described above for metaphyseal fractures can be used.

a Fig 4-14a–b

b Articular fractures.

The articular fragments are fi xed with interfragmentary lag screws while the metaphyseal fracture is stabilized with an LCP proximal tibia applied in a buttress mode.

44

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4

8

Implants

Suggested reading

Frigg R (2003) Development of the locking compression plate. Injury; 34 Suppl 2:6–10. Krettek C, Schandelmaier P, Miclau T, et al (1997) Minimally invasive percutaneous plate osteosynthesis (MIPPO) using the DCS in proximal and distal femoral fractures. Injury; 28 Suppl 1:20–30. Sommer C, Gautier E, Muller M, et al (2003) First clinical results of the locking compression plate (LCP). Injury; 34 Suppl 2:43–54. Tepic S, Perren SM (1995) The biomechanics of the PC-Fix internal fi xator. Injury; 26 Suppl 2:5–10. Wenda K, Runkel M, Degreif J, et al (1997) Minimally invasive plate fi xation in femoral shaft fractures. Injury; 28 Suppl 1:13–19.

45

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5

Intraoperative imaging

1

The role of imaging in MIPO

47

2

Hazards of radiation exposure

48

3

Safety measures

49

3.1

Protective equipment

49

3.2

Protective procedures

50

4

Portable fluoroscopy machine or C-arm

51

4.1

The machine

51

4.2

Imaging modes

52

4.3

Memory modules

52

4.4

Printer

53

4.5

3-D models

53

5

Requirements and set-up in the OR

53

5.1

Positioning

53

5.2

Obtaining maximum image

53

5.3

Obtaining imaging in the correct orientation

53

5.4

Specific positioning for MIPO procedures

54

6

Conclusion

54

7

Suggested reading

55

46

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Authors

5 1

Kok-Sun KHONG, Fareed KAGDA

Intraoperative imaging The role of imaging in MIPO

In minimally invasive plate osteosynthesis (MIPO), x-ray imaging is not only an essential requirement for preoperative diagnosis and planning but an integral part of the surgical procedure itself. With limited windows through the skin and no direct visualization of the fragments intraoperatively, image intensifiers become a key surgical tool in MIPO. However, as with any surgical equipment, the risks, benefits, and limitations must be thoroughly appreciated. Though modern plain x-rays have minimal radiation effects on the patient, frequent, prolonged, and repetitive use of intraoperative image intensifiers have greatly increased the amount of radiation exposure to the surgeon and team in the

a

Fig 5-1a–b

operating room (OR) including the anesthetist, the surgical assistants, nurses, and attendants (Fig 5-1). It is thus essential for a surgeon who practices MIPO to understand the type of x-ray generated in his or her institution, whether conventional or digital, the type of magnification exercised on the x-rays, and the size and type of image intensifier used in the OR. This will allow maximum benefit with a minimum of danger to everyone involved. ALARA—“as low as reasonably achievable”—is the principle of radiation exposure put forth by the National Committee on Radiation Protection in 1954. In practice this means keeping occupational and nonoccupational absorbed dose equivalents well below maximum allowed levels through proper safety procedures and avoiding unnecessary exposures.

b

Scatter radiation is produced by x-rays being deflected by patient anatomy, particularly bone. The amount and proportion of

“nonimage forming” radiation (bad) versus “image forming” radiation (good), is related primarily to the volume of anatomy being radiographed, (ie, more volume = more scatter radiation).

47

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2

Hazards of radiation exposure

It is the task of every responsible surgeon to be aware of the risks of ionizing radiation to himself as well as the operating team. Once exposed to radiation, any changes caused to the body are largely irreversible. Normal and abnormal variations in the host may result in undue susceptibility of cells and organs to certain forms of radiation. The only effective method of minimizing exposure is awareness and physical protection.

a

b

Some facts about radiation risks

Fig 5-2a–b

X-rays cause ionization (removal of electrons) of atoms that make up organic molecules. Ionized atoms will not bond properly on a molecular level causing disruption to the molecule and thus disrupting cellular function. This ionization effect from x-rays can be direct or indirect: Direct effects occur when molecules within the cell are disrupted due to ionization of their constituent atoms by direct energy transfer from the x-ray. This can disrupt any molecule in the cell involved in any cell process, including deoxyribonucleic acid (DNA). Indirect effects of x-rays to biological organisms are via the ionization of water, forming free radicals, which in turn react with, damage, and oxidize molecules and DNA. As human tissues contain approximately 80% water, radiolysis of water and its indirect effect on cellular molecules account for 95% of the effects of x-rays on the organism.

radiation exposure.

If the DNA molecule is affected, the resulting damage may be permanent or reversible by DNA repair processes. DNA damage from ionization is usually either a change in the nitrogenous base pair (changing the genetic code) or cross linking of strand (interference with translation of the code)

Different forms of chromosome damage following

(Fig 5-2). This may result in: Genetic repercussions Instant cell death (large doses cause DNA breakdown) Reproductive death (cells unable to divide) Interphase death (cell death without attempt at division) Mitotic death (cell death after one or more divisions) Mitotic delay (delay in cell division) The Law of Bergonie and Tribondeau states that “the radiosensitivity of cells is directly proportional to their reproductive ability activity and inversely proportional to their degree of differentiation”. Muscle and bone are relatively radioresistant, but skin, reproductive cells, and hematopoetic cells are radiosensitive. The biological damage to living organism from radiation exposure is known as somatic effects. Early effects are due to highdose radiation and not typical of diagnostic imaging radiation. Chronic effects appear months or years after exposure and can be seen with multiple low-dose radiation exposure over years

48

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5

Intraoperative imaging

such as in diagnostic radiology. The main categories of these chronic somatic effects are: Cancer induction (eg, skin cancers, leukemias) Damage to the fetus Cataractogenesis Thyroid disease Shortening of life span Stochastic events (nonthreshold effects) are effects in which the probability of occurrence is related to the cumulative dose but not to the severity of effects (Fig 5-3). These include genetic damage and carcinogenesis. Carcinogenesis includes skin cancers especially on hands of medical radiation workers, leukemia, and thyroid carcinomas. Since the introduction of safety measures, there has been no reported increase in rates of cancer in this subgroup.

3

3.1

Safety measures

Protective equipment

Gowns with 0.5 mm lead equivalent can cover about 80% of active marrow and can reduce the effective dose by a factor of 16. Thyroid shields protect the neck area and can reduce the radiation exposure to the gland by a factor of 13; without them radiation exposure is 70 times more. Lead glasses decrease exposure of the eyes (which may lead to cataracts)—0.15 mm lead equivalent goggles attenuate 70% of beam energies (Fig 5-4). Lead screens provide additional protection for OR personnel who do not wear lead protection. The thick lead gloves common in radiology suites are cumbersome and are not used in the OR.

Nonstochastic events (threshold limited effects) are effects that will not occur below a certain dose and whose severity depends on the dose. Examples are cataractogenesis and reproductive cell damage.

Lead goggles

Risk of DNA damage (cancer, birth defect)

Thyroid shield

Gown

No effects measured Radiation dose

Fig 5-3

Risk of DNA damage increases in relation to the cumulative

Fig 5-4

Protective equipment.

dose, but not to the severity of effects (stochastic events).

49

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3.2

Protective procedures

Simple measures such as moving as little as 0.5 m away from the part being radiographed (a step or two back) will reduce the amount of radiation exposure dramatically, and at 3 m there will be negligible radiation scatter to the person, by the principle of “inverse square law” (inversely proportional to the square of the distance from the source). The surgeon and assistant should face the image intensifier source during exposure as side-facing by the surgeon may allow increased radiation exposure. The exposure to anesthetist has been recorded as negligible, but the amount of exposure to the surgical assistant has been recorded to be greatest. The parts of the body at greatest risk are the hands of the surgeon or the assistant. All efforts must be made to keep hands away from the field of exposure. Application

Effective dose

The International Commission on Radiation Protection (ICRP) recommends a limit of effective dose of 20 mSv (millisievert) per year, averaged over 5 years (100 mSv in 5 years), with the further provision that the effective dose should not exceed 50 mSv in any single year. Table 5-1 shows the dose limits for individual anatomical areas. Most studies have shown that dose limits are not exceeded during orthopedic procedures. For practical purposes, the best methods for reducing potential exposure to radiation are the following: Reduce exposure time with modern efficient machine. Increase distance between limb and surgeon. X-ray source position (“face the beam”). Reduce air gaps (receiver close to limb). Use digital magnification (keep receiver close to limb). Collimation (narrow the window) of the beam (Fig 5-5).

Dose limit Occupational

Public

20 mSv per year,

1 mSv in a year

averaged over defined periods of 5 years Annual equivalent

Occupational

Public

150 mSv

15 mSv

the skin

500 mSv

50 mSv

the hands and

500 mSv

dose in: the lens of the eye

feet

Tab 5-1

Recommended dose limits of radiation exposure

in mSv (millisievert).

Fig 5-5

Collimation of the beam reduces potential exposure to

radiation.

50

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5

Intraoperative imaging

Use the maximum voltage possible. Ensure image memory is activated and used. Use radiation shields and other equipment. Monitor the amount of radiation used per exposure and consciously reduce the exposure time (Fig 5-6). Never use the C-arm with the receiver below or as a “hand table”; scatter from metal surfaces or instruments will reach the eyes and thyroid region.

4

The OR fluoroscope (or C-arm) is a portable machine that has revolutionized orthopedic surgery. The surgical team can be certain to a large extent of the accuracy of fracture reduction and placement of implants. Each machine may have different functions and modes. It is essential to familiarize oneself with the machine available in one’s practice. 4.1

NAME PATIENT ID PROCEDURE ACCESSION

Generator mode Fluoro HLF/Snapshot Film Totals

Field of view Normal Mag 1 Mag 2 Mode Continuous Pulsed

DATE PHYSICIAN

Time 312.0 0.0 0.0 312.0

Cumulative dose s s s s

100.0 0.0 0.0 119.0 797.6

% % % rad/cm 2 mrad

Time

Cumulative dose

187.1 s 125.0 s 0.0 s

55.1 % 44.9 % 0.0 %

Time

Cumulative dose

312.0 s 0.0 s

100.0 % 0.0%

DOSE SUMMARY

Fig 5-6

Monitoring the amount and exposure time of radiation.

Portable fluoroscopy machine or C-arm

The machine

The C-arm itself mounts a radiation source with a collimator screen (x-ray tube unit) which allows gamma rays to be beamed to the photosensitive receiver array (image intensifier) (Fig 5-7). The received image that has traversed the body will differ in intensity and the image captured is processed electronically to produce an enhanced picture on a digital screen. The radiation power (kilovolt, kV) and exposure (milliampere, mA) are usually automatically set to produce an optimal image and varies with the mass through which the beam passes. In obese patients more radiation will be emitted, usually without the knowledge of the operating team. They must thus be aware of this function. The receiver diameter is usually 9 in, 12 in, and rarely 18 in with a larger image area with the latter, which is preferred in orthopedic surgery. The direct beam width is constrained not to exceed this diameter, but the scatter is increased with the larger receiver size, due to wider beam width. A common and dangerous mistake is to position the receiver upside-down or as a “hand table” as this allows beam scatter to reflect off metallic instruments toward the eyes and neck of the surgeon. Obese patients or large limbs also produce more scatter radiation, so the team should stand further away in such situations.

51

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4.2

Imaging modes

Several modes of imaging may be available on the machine: continuous fluoroscopy (which would emit the most amount of radiation, up to five times that of pulsed fluoroscopy) can be used for dynamically evaluating joint motion; single pulse mode fluoroscopy, which is commonly used; and pulsed screening mode, which gives up to 30 pulses per minute. By allowing only single pulses in pulsed screening mode, a substantial reduction in the amount of radiation exposure occurs.

The image can also be magnified for better resolution especially for the articular surface, but at the cost of a higher dose of radiation. 4.3

Memory modules

Modern machines are able to store large numbers of highresolution images (4–99). This allows the user to recall the appropriate ones, or to print out for documentation. The dose summary can also be recorded and printed (Fig 5-6).

Image intensifier

X-ray tube unit

Fig 5-7

C-arm with radiation source (x-ray tube unit) and receiver array (image intensifier).

The received image is processed electronically to a digital screen.

52

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5

4.4

Intraoperative imaging

Printer

A high-resolution thermal printer allows hard copies of the selected images to be kept, or the image can be stored on some form of digital media and printed onto fi lm either digitally or in a dark room. However, the soft x-ray resolution produced by the C-arm is still not adequate or permanent enough for a stand-alone document. A routine postoperative plain (hard) x-ray is still recommended. 4.5

3-D models

Some companies are now producing C-arm machines that can automatically acquire multiplanar images, just like a computed tomography (CT) scan, and reformat them into 3-D images. These can be linked to computer navigation devices and reduces intraoperative exposure.

Obtain only the necessary minimum number of images. Rely on stored images without the need to reexpose. Minimize use of magnification. Collimate the image whenever possible. 5.1

The machine body is usually placed opposite the surgical team. This means in most cases that the source is below and the receiver is above in a standard AP projection. In the lateral projection the source is usually at the surgeon’s side. It is of critical importance that the surgical team is aware of the increase in scattered radiation in this lateral projection. One way to avoid this is to use the “over-the-top” C-arm position with the receiver/intensifier on the surgeon’s side. Another way is to stand further away—3 m being a safe distance—or behind a lead screen during lateral exposures. 5.2

5

Requirements and set-up in the OR

It is easy to overuse intraoperative fluoroscopy as the surgeon strives to perform a difficult operation. In order that radiation exposure should be minimized, these points should be followed: Always perform preoperative planning before the operation. Inform your assistants and staff what you have planned. Inform the radiographer where you want the C-arm positioned. Perform a trial screening in the projections you need after positioning the patient and ensure the radiographer remembers these positions, or marks the floor positions for the wheels. Adjust the patient’s position in case you need special projections.

Positioning

Obtaining maximum image

By placing the receiver of the C-arm as close as possible to the limb or bone, a smaller image of the bone is obtained but of a much larger area, allowing a better overall assessment of the alignment (Fig 5-8). 5.3

Obtaining imaging in the correct orientation

Obtaining a view on the image intensifier correctly aligned to the surgeon’s position relative to the limb will greatly simplify surgery. Image intensifier images can be fl ipped horizontally (mirror image), vertically, and rotated. This will allow the image of the bone to be viewed in the same orientation as the surgeon is viewing the limb. Reduction maneuvers, implant insertion, and screw placement are greatly facilitated. It may be necessary to reorientate the image when the C-arm is switched to the lateral position. In addition it is also beneficial that, as far as possible, the beam of the x-ray should travel 53

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perpendicular to the limb or bone. Oblique views should be avoided if possible. However, this may not be possible for the proximal humerus and proximal femur, and if this is understood allowances can be made. 5.4

Specific positioning for MIPO procedures

Each chapter for the different surgical techniques will show recommended positions for the C-arm.

6

Radiation in the operating environment is unavoidable today during many orthopedic procedures, including MIPO. It is possible that there may be increased incidence of radiation overexposure among orthopedic surgeons, mainly due to lack of awareness of the danger of cumulative radiation. Protection is simple, and it is easy to adhere to the adage “as low as reasonably achievable” (ALARA).

b Fig 5-8a–b

Conclusion

a

Placing the receiver closed to the limb results in an image of a large area of bone (a), as opposed to a large but

unclear image when the limb is placed near to the radiation source (b).

54

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5

7

Intraoperative imaging

Suggested reading

Smith GL, Wakeman R, Briggs TW (1996) Radiation exposure of orthopaedic trainees: Quantifying the risk. J R Coll Surg Edinb; 41(2):132–134.

Dewey P, Incoll I (1998) Evaluation of thyroid shields for reduction

Tasbas BA, Yagmurlu MF, Bayrakci K, et al (2003) Which one is

of radiation exposure to orthopaedic surgeons. Aust N Z J Surg;

at risk in intraoperative fluoroscopy? Assistant surgeon or orthopaedic

68(9):635–636.

surgeon? Arch Orthop Trauma Surg; 123(5):242–244. Epub 2003

Giachino AA, Cheng M (1980) Irradiation of the surgeon during

May 10.

pinning of femoral fractures. J Bone Joint Surg [Br]; 62–B(2):227–229.

Theocharopoulos N, Perisinakis K, Damilakis J, et al (2003)

Goldstone KE, Wright IH, Cohen B (1993) Radiation exposure to

Occupational exposure from common fluoroscopic projections used in

the hands of orthopaedic surgeons during procedures under

orthopaedic surgery. J Bone Joint Surg [Am]; 85(9):1698–1703.

fluoroscopic x-ray control. Br J Radiol; 66(790):899–901. ICRP Publication 60 (1991) 1990 Recommendations of the International Commision on Radiological Protection, 60. Annals of the ICRP; 21:72–79. Jones DG, Stoddart J (1998) Radiation use in the orthopaedic theatre: A prospective audit. Aust N Z J Surg; 68(11):782–784. Keenan WN, Woodward AF, Price D, et al (1996) Manipulation under anaesthetic of children’s fractures: Use of image intensifier reduces radiation exposure to patients and theatre personnel. J Pediatr Orthop; 16(2):183–186. Lo NN, Goh PS, Khong KS (1996) Radiation dosage from use of the image intensifier in orthopaedic surgery. Singapore Med J; 37(1):69–71. McGowan C, Heaton B, Stephenson RN (1996) Occupational xray exposure of anaesthetists. Br J Anaesth; 76(6):868–869. Muller LP, Suffner J, Wenda K, et al (1998) Radiation exposure to the hands and the thyroid of the surgeon during intramedullary nailing. Injury; 29(6):461–468. O’Rourke PJ, Crerand S, Harrington P, et al (1996) Risks of radiation exposure to orthopaedic surgeons. J R Coll Surg Edinb; 41(1):40–43. Sanders R, Koval KJ, DiPasquale T, et al (1993) Exposure of the orthopaedic surgeon to radiation. J Bone Joint Surg [Am]; 75(3):326–330. Smith GL, Briggs TW, Lavy CB, et al (1992) Ionising radiation: Are orthopaedic surgeons at risk? Ann R Coll Surg Engl; 74(5):326–328.

55

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6

Computer assisted surgery in MIPO

1

Introduction

57

2

Computer guided surgery technology

57

3

Evolution of navigation

58

4

Navigation of straight objects

58

5

Nails

59

6

Plates

59

7

Reduction

59

8

Accuracy

60

9

Applications

60

10

Equipment and set-up

60

11

Sample case—sacroiliac screw fixation navigation

62

Future

65

12.1

Basic connectivity

65

12.2

Fragment segmentation

65

12.3

Integration with implants and instrumentation

65

13

Suggested reading

65

12

56

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Author

6 1

Merng Koon WONG

Computer assisted surgery in MIPO Introduction

The essence of minimally invasive surgery (MIS) is to limit surgical trauma to the fracture site. This essentially translates to minimal disturbance of the blood supply in the area of trauma whatever the origin of the blood supply, be it endosteal, periosteal, or muscular. This preservation of blood supply will allow reparative processes to proceed with minimal disruption. Minimal skin incision and soft-tissue dissection help to lower the risk of infection and reduce the intensity of postoperative pain, and have the added advantage of promoting faster functional recovery. These requirements of fracture management necessarily limit surgical exposure; critically to the fracture site and less so to the rest of the main proximal and distal fragments. Thus open visualization of reduction and fi xation of a multifragmentary fracture is a luxury that should be avoided in order to preserve biology, which is paramount to fracture healing via callus. Realistically, respect of this “no touch” technique at the fracture site creates great technical difficulties in reconstruction of length as well as alignment both in terms of translation and rotation. Excessive radiation for visualization is inevitable. Moreover, the C-arm projects a 2-D image at any one time with consequent need for orthogonal views which still do not approximate the visual let alone tactile feedback of open fracture visualization and manipulation. There are two main exceptions to the preeminence of biology over mechanics in fracture repair. Intraarticular fractures absolutely require anatomical and stable fi xation to avoid joint surface incongruence and future posttraumatic arthrosis. Strain-intolerant simple transverse or short oblique fractures predictably result in impaired union if absolute stability is not engineered during surgery.

2

Computer guided surgery technology

The past two decades have witnessed rapid advances in imaging technology. Today it is not difficult to achieve 3-D reconstructions of complex fractures from CT, MRI, or even PET scan data. It is a pity, but perhaps not surprising, despite such amazing preoperative diagnostic imaging, we do not see any provision of that information in a real-time interactive intraoperative manner. Computer guided surgery could improve intraoperative visualization of fracture reduction and fi xation through its ability to provide real-time simultaneous presentation of multiple views of fracture anatomy thus decreasing the use of radiation (Fig 6-1). In addition, multiple views of important limb alignment end points allow restoration of length and alignment to the injured limb.

Fig 6-1

Parallel visualization of multiple fluoroscopic views of

relevant anatomy. Virtual representation of tools and implants.

57

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3

Evolution of navigation

Early efforts took care of correcting some intrinsic inaccuracies in the system of image acquisition. Computerized scanning methods such as CT and MRI have algorithms built in to correct for ray scatter and thus image distortion. However, there is intrinsic difficulty in registration or matching of intraoperative data to allow projection of preoperative CT and MRI data. There is additional difficulty checking for intraoperative changes in relationship of fracture fragments as very few operating rooms have built-in CT or MRI.

C-arm imaging techniques are well suited to monitor intraoperative changes in fracture fragment relationships. However, there is still significant image distortion due to the central projection of x-rays and spheric intensifier tubes (pin cushion distortion), electromagnetic influences (magnetic field of earth) and mechanical flexing of the heavy C-arm at different inclinations (Fig 6-2).

4

Navigation of straight objects

The obvious next step in the evolution was the tracking of straight nonbending instruments such as pointers and drills (Fig 6-3).

a

c

b

c

d

a

e

b Fig 6-2a–b

Fig 6-3a–e

a

a–d Set of navigation tools. Sharp pointer (a), ortho pointer (b), drill

Gravity may change the position of the x-ray tube toward the intensifier tube.

b

guide handle with different sleeves and matching drills (c),

Undistorted image (left), pin cushion distortion (middle), S-distortion (right) intensifi er tube.

Image Guided Surgery (IGS) toolset (d). e

Navigation of a drill bit with a rigid nonbending drill guide.

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6

5

Computer assisted surgery in MIPO

Nails

There are many benefits of navigated intramedullary nail insertion. Finding and drilling the entry point becomes reliable due to parallel visualization of multiplanar views of the proximal tibia or femur. Multiple fracture fragment tracking allows for threading the distal fragment with the nail during the navigated reduction. Special planning steps in the workflow enable the surgeon to control length, axis, and rotation of long-bone fractures. C-arm images of the distal interlocking holes can be used for planning and targeting the interlocking screws, taking care of the perceptible bending and torsion of the nail after negotiating the intramedullary canal (Fig 6-4). Navigation of a slightly curved but rigid nail is the logical next step.

Fig 6-4

Navigation screen of a femoral reduction. The two upper

6

Plates

Precontoured plates can also be navigated. The trajectory of the locking head screws (LHS) in the less invasive stabilization system (LISS) could have virtual representation to allow easy targeting. Intraoperatively contoured plates can be registered and tracked subsequently. Yet later deformation of the plate must be tracked to be properly represented.

7

Reduction

Tracking of fracture fragments requires a reference array in each fragment. The available array fi xtures therefore limit the fragment size to be tracked (Fig 6-5). In a further development automatic segmentation could visualize individual fragments in 3-D.

a

b

views show AP and lateral fluoroscopic images of the fracture region

Fig 6-5a–b

together with the current position and orientation of the bone frag-

fi xation tools for the reference arrays. Minimally invasive reference

ments. The two lower views give a 3-D representation of important

arrays (MIRA) are attached to the bone either with a 5 mm Schanz

parameters such as axis alignment, antetorsion and leg length.

screw (1-pin MIRA, a) or two 3 mm K-wires (2-pin MIRA, b).

The traceable fragment size depends on the size of the

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8

Accuracy

The accuracy of most commercial navigation systems is better than 2 mm after calibration. However, inaccuracies can be introduced by inadequate handling of the navigation equipment. Any relative movement of the tracking arrays against their bony support during surgery increases inaccuracy, directly depending on the extent of movement. The surgeon must check the status and accuracy of his bone tracking during operation and he must make provisions to avoid such movement.

9

Applications

10

Equipment and set-up

The basic equipment for navigation consists of reference arrays, tools, a camera, a computer, a screen, and an image intensifier. Reference arrays are placed on the C-arm of the image intensifier, on tools, and on the patient’s bone. The camera analyzes the reference positions optically, while the computer integrates localization data and image data of the C-arm. The screen displays the integrated information and serves as an interface to operate and control the system. The optical analysis of the reference array position and the system handling by the surgeon requires some care when planning the OR set-up for navigated procedures.

The time required for set-up and additional resources need to be considered when navigating (Fig 6-6). Of course the added value of the new method must compensate for those additional demands. Especially in complicated anatomical situations with difficult approaches through small incisions, navigation can be a great help, eg, in the targeting of sacroiliac screws or targeted biopsies of deep bone structures. Intraoperative x-rays can be cut down considerably during the insertion of intramedullary nails, compensating the time needed for the set-up by shortening the time needed for C-arm handling. In the same time length, axis and rotation changes in long-bone fractures are accessible online to the surgeon, avoiding malrotation and limb shortening after intramedullary nailing.

Fig 6-6

Additional set-up time and resources are required for

computer assisted navigation.

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6

Computer assisted surgery in MIPO

In most cases the caudolateral position of the system and caudal position of the camera offer the best reference visibility to the camera, while the surgeon has access to the touch screen for system handling. To register images acquired with the C-arm, the fluororegistration kit is mounted on the image intensifier. For accurate use, the kit must be set flush and centered on the image intensifier. The kit can be sterilized. It is recommended to place it sterile over the draping to avoid compromising the visibility by the drape. If the surgeon wishes to handle the system himself, the touch screen can be covered with a sterile draping. The camera handle can be draped similar to the illumination handles. The reflective markers are sterile and disposable. Resterilization damages their reflective surface and so leads to inaccuracy. The markers are tightly screwed on the threaded sockets of the arrays prior to the procedure. For accuracy reasons, no blood, liquid, stain or taint is tolerable, as they spoil the circular light reflex and so might lead to invisibility of a reference array or, worse, inaccurate navigation data.

iliac crest for unstable traumatic pathologies when draping the patient should also be borne in mind. A Y-shaped reference array is fi xed to a stable structure of the pelvis to track the bony pelvis during navigation. The reference position should be chosen carefully to avoid collisions with the C-arm and to enable camera visibility during the procedure. A 5–6 mm Schanz screw or two 3–5 mm K-wires are introduced axially into the iliac crest to serve as base for a one-pin or a two-pin fi xation of the minimally invasive reference array (MIRA). The MIRA is then fi xed on the pins. When using one pin, great care should be given to a stable and fi rm bone contact of the MIRA on the bone surface. Any movement of the bone relative to the spheres will lead to inaccuracy of the navigation. In case a reference fi xation has become unstable, always check for stability and control accuracy by touching the landmarks with the pointer. If a reference array loosens, its original position is usually hard to fi nd. To continue navigating, acquire new images after refi xing the reference.

For sacroiliac screw fi xation the patient is positioned supine. Other positions are possible, as long as visibility of the fluoroscopic anatomy and the reference arrays are adequate. To facilitate access to the incision point, the procedure side can be elevated. When placing the patient on the table, allowance should be made for space requirements of the C-arm for inlet and outlet images of the pelvis especially in the longitudinal axis of the patient. The reference attachment site on the ipsilateral iliac crest for stable degenerative pathologies or on the contralateral 61

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11

Sample case—sacroiliac screw fixation navigation

Case description

A 44-year-old male was transferred from another hospital 3 days after a fall from the fourth storey of a building, during which he sustained the following injuries (Fig 6-7): Vertically unstable fracture of the left hemipelvis with a Morel–Lavallé lesion Burst fracture of L2 vertebra with neurological deficit Fracture dislocation of left elbow The initial treatment consisted of stabilization of his prerenal failure, early disseminated intravascular coagulopathy and severe anemia. Skeletal traction was applied to the left leg.

management. Open compression screws would face a very high risk of infection due to a degloved buttock. An ilioinguinal approach would also subject the patient to both a high infection risk with the suprapubic catheter in place as well as prolonged open surgery with its antecedent systemic load in terms of bleeding and anesthesia. Preoperative preparation

The patient was positioned supine on an extended radiolucent operating table. The C-arm was positioned to allow pelvic inlet, outlet, and shoot-through lateral sacral views without hitting the post of the operating table. (The C-arm should also be trackable via the infrared cameras of the navigation system in all these views.) Indirect reduction

Indication

The critical general and local condition (Morel–Lavallé lesion) of the patient required a minimally invasive fi xation of the pelvic fracture as the fi rst building block in his surgical

a

b

Restoration of limb length was maintained by skeletal traction through the left lower limb. Reduction of rotation was maintained by taping the knees together.

c

Fig 6-7a–c a

Vertically unstable fracture of left hemipelvis with a high fl oating bladder drained via a suprapubic catheter.

b

Pelvic fracture associated with Morel–Lavallé degloving lesion.

c

Segmental fracture of left sacrum involving the neural foramina.

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6

Computer assisted surgery in MIPO

Surgical approach

The patient was cleaned and draped. The reference base was affi xed onto the left anterior superior iliac spine. X-rays of the pelvic inlet, outlet, and shoot-through lateral sacral views were acquired and transferred to the navigation computer (Fig 6-8). The trajectory of the drill would be tracked and represented by colored lines superimposed over the stored key fluoroscopic views. The percutaneous insertion point for the drill as well as the direction of drilling was guided by the navigation system. The surgeon had access to real-time trajectory information in

Fig 6-8

Patient is positioned supine and key views of the anatomy

are acquired. The reference base is affi xed onto the left anterior

four key fluoroscopic views making this procedure much quicker and more reliable. Before the advent of computed assisted navigation, the drill was advanced while alternating between the inlet and outlet pelvic view. Since the pelvis is oriented at 45º in the sagittal plane this makes the appreciation and consequently the drill targeting extremely difficult (Fig 6-9). The drill tracks into the vertebral bodies of S1 and S2 were replaced with K-wires for the 7.3 mm cannulated cancellous bone screws. The fi nal positions of the K-wires were

Fig 6-9

Clockwise from the top left: The pelvis PA, shoot-through

lateral sacral view, the outlet pelvic view, and the inlet pelvic view.

superior iliac spine.

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double-checked with the C-arm to ensure the accuracy of the navigation computer. Importantly, there should not be hardware in the spinal canal. These K-wires were replaced with the cannulated cancellous bone screws (Fig 6-10).

9 months postoperatively, x-rays showed healing of the pelvic/ sacral fractures and the patient was ambulatory with a cane.

Postoperative x-rays were taken to confi rm the C-arm images (Fig 6-11). 1 week later L2 decompression corpectomy and fusion were performed.

a

b

a

b

Fig 6-10a–b The view through lateral sacrum and inlet pelvic x-rays to check that no hardware was in the spinal canal.

Fig 6-11a–b

Immediate postoperative x-rays.

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6

12

Computer assisted surgery in MIPO

Future

Despite intensive developmental efforts there remain shortcomings in three main aspects.

13

Suggested reading

DiGioia AM 3rd, Jaramaz B, Colgan BD (1998) Computer assisted orthopaedic surgery. Image guided and robotic assistive technologies. Clin Orthop Relat Res; Sept (354):8–16.

12.1

Basic connectivity

Grutzner PA, Suhm N (2004) Computer aided long-bone fracture treatment. Injury; 35 Suppl 1:S-A57–64.

Wired components increase logistic demand for space and connection management. This obviously increases set-up time.

Nolte LP, Beutler T (2004) Basic principles of CAOS. Injury; 35 Suppl 1:S-A6–16. Nolte LP, Slomczykowski MA, Berlemann U, et al (2000) A new approach to computer-aided spine surgery: fluoroscopy-based surgical

Wireless components suffer from slower refresh rates and thus lower real-time accuracy.

navigation. Eur Spine J; 9 Suppl 1:S78–88. Schmucki D, Gebhard F, Grutzner PA, et al (2004) Computer aided reduction and imaging. Injury; 35 Suppl 1:S-A96–104.

In terms of ergonomics, wireless low profi le with an adequate refresh rate is a prerequisite for widespread application of this technology. 12.2

Fragment segmentation

The ability to extract bony outlines from imaging data is the fi rst step in tracking individual fragments during intraoperative manipulation and reduction. From there it is but a small step to morph a virtual representation of bone to enhance visual representation of fragments during surgery. 12.3

Integration with implants and instrumentation

There are strong efforts by the AO Technical Commission (AOTK) to integrate implants into navigation as well as to design implants and instrumentation to align with the concepts of biological and minimally invasive surgery. Obviously integration of all three aspects will see fruition in the future.

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7

Reduction techniques

1

Introduction

67

2

Goals of reduction

67

2.1

Articular fractures

67

2.2

Diaphyseal fractures

67

3

Methods of reduction

67

3.1

Indirect reduction

68

3.2

Direct reduction

68

4

Reduction techniques

68

Articular fractures

68

4.1

4.2

4.1.1

Indirect reduction

4.1.2

Direct reduction

Diaphyseal fractures 4.2.1

Indirect reduction

4.2.2

Direct reduction

72

5

Summary

77

6

Suggested reading

77

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Authors

7 1

Frankie KL LEUNG, Shew-Ping CHOW

Reduction techniques Introduction

There has, over the years, been a change in the concept of fracture fi xation and the emphasis today is on the preservation of the biology of bone and soft tissue. The preserved blood supply leads to a more rapid fracture union and lessens the chance of complications such as delayed union, implant failure, and infection. Similarly, in fracture reduction it is essential that reduction techniques applied do not cause further damage to the blood supply and soft-tissue attachments in the fracture zone. It is clearly vital to understand the goals of the reduction and how this can be accomplished with a maximum preservation of biology.

2

Goals of reduction

It is well accepted that fracture reduction is a crucial factor in achieving bony union and preserving form and function. The degree of accuracy of reduction can, however, range from axial realignment to anatomical reduction of each fracture fragment. The surgeon has to select the appropriate technique and the degree of accuracy of reduction based on the fracture pattern and the segment of bone involved. The key is to use the method of reduction causing least damage to the soft tissue and blood supply at the fracture area. 2.1

Articular fractures

In intraarticular fractures, anatomical reduction and stable fracture fi xation must be achieved in order to allow good healing of the articular cartilage. Precise reduction is of crucial importance to avoid local overload and exposure of subchondral bone and thus reduce the incidence of posttraumatic arthrosis. After achieving stable fi xation with interfragmen-

tary compression, early range-of-motion exercises can be started. In some cases, continuous passive motion therapy can promote healing and the formation of hyaline cartilage rather than fibrocartilage. 2.2

Diaphyseal fractures

In multifragmentary diaphyseal fractures, it is only essential to achieve functional reduction, which consists of restoration of length, mechanical axis, and rotational alignment of the main fracture segments that carry the joint surfaces. It is unnecessary to achieve precise reduction of each fracture fragment. Such action may in fact jeopardize the blood supply to the bone. The two main fracture fragments are stabilized without disturbing the multifragmentary zone and its vascularity, the aim being to promote indirect bone healing within 4–6 weeks. In contrast, simple diaphyseal fractures, such as transverse, oblique, or spiral fractures, should preferably be treated by anatomical reduction and compression fi xation to obtain absolute stability so that implant failure from high stress concentration may be avoided.

3

Methods of reduction

In MIPO, the aim is to achieve fracture reduction and fi xation without exposure of the fracture site. Thus, whenever possible, indirect reduction should be the method of choice. However, this may not always be possible as the quality of reduction achieved may not be acceptable. Under such circumstances, it may become necessary to resort to direct reduction methods to obtain the desired accuracy of reduction. Even in such instances, small incisions with minimal soft-tissue dissection should be the rule. 67

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3.1

Indirect reduction

For indirect reduction, the fracture site is not exposed and remains covered by the surrounding soft tissue. Hence there is maximal preservation of the biology surrounding the bone fragments. Reduction is accomplished using instruments or implants introduced away from the fracture zone. To achieve reduction, traction is usually applied in the long axis of the limb. This only works when the fragments are still connected to some soft tissue. However, since there is no direct visualization of the fracture site, the reduction may not be anatomical. In most cases, there will be gaps between the fracture fragments and healing across the fracture gaps will be achieved by callus formation. The main indications for indirect reduction are multifragmentary diaphyseal fractures, although some minimally displaced simple articular fractures are also amenable. An image intensifier is essential to check the quality of the reduction, while arthroscopy can be helpful in articular fractures. 3.2

Direct reduction

In direct reduction, the fracture site is exposed and the fracture fragments directly manipulated. All maneuvers are seen and controlled under direct vision. This type of reduction technique is easier than indirect reduction and the reduction more precise. However, application of reduction tools often damages the soft tissue surrounding the bone, thus affecting the vascularity of the bone fragments. There are several indications for direct reduction. Simple diaphyseal fractures are often treated by anatomical reduction and rigid internal fi xation. It is technically straightforward and the result is easy to assess. The aim of treatment is absolute stability that will result in direct bone healing. Even then, the

surgical exposure used should just be adequate for the direct reduction to be carried out with minimal stripping of the periosteum and the rest of the fracture fi xation can then be performed in a similar fashion to percutaneous plate fi xation if possible. For articular fractures, the success of surgery will rely on restoration of a congruent articular surface. A small direct incision over a specific articular fragment to achieve reduction may be necessary. A preoperative CT scan is necessary to plan the appropriate approach and reduce the exposure required for reduction of the articular fracture.

4

4.1

Reduction techniques

Articular fractures

Various reduction techniques can be applied depending on the pathoanatomy of the articular fracture. The aim is to obtain anatomical reduction followed by stable fi xation. 4.1.1

Indirect reduction

Closed indirect reduction may be achieved by manual traction. This forms the basis of ligamentotaxis. However, this is only successful if the bony fragments still retain their soft-tissue attachments such as the joint capsule or ligaments. The quality of reduction in these indirect methods can be monitored by an image intensifier or arthroscopy. Once the reduction of the articular surface is deemed satisfactory, fi xation of the intraarticular component of the fracture should be performed, preferably by percutaneous fi xation methods.

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7

4.1.2

Reduction techniques

Direct reduction

In order to obtain anatomical reduction and a congruent joint surface, it is often necessary to perform direct reduction. This direct reduction can be achieved either by open methods or through remote access. Whatever the approach, it is necessary to minimize the adverse effects of direct reduction when exposing the fracture area but, at the same time, ensuring that the quality of reduction is not compromised.

In intercondylar fractures of the distal femur, direct reduction through a parapatellar arthrotomy is usually required to obtain an anatomical reduction of the joint surface. Flexion of the knee with a support will help to align the fracture, while Schanz screws inserted as manipulators into both condyles also help to reduce the articular fractures. A distractor may be applied to help reduce the metaphyseal fracture (Fig | Anim 7-3).

In multifragmentary articular fractures of the tibial plateau in which the fragments are of considerable size, direct reduction through an arthrotomy or under fluoroscopic or arthroscopic guidance is usually required. In split depression fractures, reconstruction of the depressed fragment is best achieved using an open technique by separation of the split fragment and restoring the depressed articular fracture. In a simple wedge fracture extending from the articular surface to the metaphysis, the exact reduction of the spike of the articular fragment to the corresponding defect in the metaphysis will lead to the anatomical reduction of the articular surface without the need to expose the joint. This reduction can be performed either through a small incision over the spike or percutaneously using a manipulator, the reduction being maintained by K-wires or a large pelvic reduction clamp (Fig 7-1). An example of the application of direct reduction through remote access in articular fractures is in pure depression fractures of the tibial plateau. Such fractures should be elevated and reduced directly via a window created in the metaphyseal cortex followed by bone grafting to provide support for the elevated articular fragments. The whole procedure is carried out under fluoroscopic guidance (Fig 7-2).

Fig 7-1

A large pelvic reduction clamp can be used, especially in

fractures around the knee and ankle.

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Fig 7-2a–e

Fluoroscopic guidance of direct reduction through remote access in a depressed

fracture of the tibial plateau. a

CT scans show a depressed articular fragment at the lateral tibial plateau. Additionally there is a split fracture of the medial tibial condyle.

b–c C-arm AP and lateral view show the impactor following the enlarged tract to elevate the depressed articular fragment. d–e The reduction is maintained first by K-wires which are then replaced by cancellous

a

b

bone screws.

c

d

e

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7

Reduction techniques

Animation

a

b Fig | Anim 7-3a–c a–b The pull of the gastrocnemius muscle can be neutralized by knee flexion thus providing realignment of the articular fragment. c

Direct reduction of femoral condyles with Schanz screws on T-handles supplemented by indirect reduction with trac-

c

tion using the distractor.

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4.2

Diaphyseal fractures

4.2.1

Indirect reduction

Indirect reduction is a demanding technique. Considerable difficulty may be encountered during the process as the fracture fragments are neither visualized nor directly manipulated. The surgeon must have a clear understanding of what constitutes normal anatomy for correct restoration of axis, rotation, and length of the limb, and also of the various methods used for checking the adequacy of the reduction obtained. Fluoroscopic guidance is indispensable to carry out indirect reduction.

For most diaphyseal fractures, manual traction is effective. This is best carried out under fluoroscopic guidance and for this a radiolucent operating table is most helpful. Traction can also be applied with the help of an external fi xator or large distractor. Irrespective of the chosen method of applying traction, once satisfactory reduction has been obtained, it is advantageous to lock the position of the fracture fragments with the aid of an external fi xator or a large distractor. This will facilitate the subsequent fi xation of the fracture with the selected implants.

Traction

The application of traction is an important step in achieving reduction by indirect means. Traction helps to restore length and can be used to correct rotational malalignment and, to a certain degree, axial malalignment. For traction to be successful, the fracture fragments must retain their soft-tissue attachments as it makes use of the principle of ligamentotaxis. The fracture must also be relatively recent as soft-tissue contractures will prevent effective reduction. There are several ways in which traction can be applied: A traction table may be used for diaphyseal fractures of the lower limb, especially when the surgeon is operating alone. In this way, an adequate degree of traction can be maintained even when there is a lack of surgical assistance (Fig 7-4). One of the disadvantages of using a traction table is the difficulty of obtaining fi ne adjustment of the reduction which could otherwise be achieved manually if the patient was lying freely. There is also difficulty in assessing the quality of the reduction, as comparison with the intact side is not feasible.

Fig 7-4

A traction table should be used only if closed reduction is

possible and if traction will maintain the reduction, especially when the surgeon is operating alone.

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7

Reduction techniques

Supporting pads

Muscle forces acting on the fracture fragments often determine the pattern of displacement of a fracture. Traction alone can restore the normal length of the bone but may exaggerate the axial malalignment instead of correcting it. A supporting pad can be used to correct a recurvatum deformity (Fig 7-5). It is most often used in periarticular fractures such as those affecting the distal femur. External fixators and distractors

External fi xators and large distractors are most useful tools for reducing and maintaining the reduction of multifragmentary fractures of the diaphysis. Not only can they be used for applying longitudinal traction, but they also allow manipulation to correct axial and rotational malalignments. Following preparation of the injured limb under aseptic technique, Schanz screws are inserted into the main fracture fragments away from the fracture zone so that they will not interfere with the subsequent surgical procedure. Manipulation of the fracture under fluoroscopic guidance is performed and once satisfac-

tory reduction is obtained, the reduction is maintained by tightening the clamps on the fi xator or distractor. Manipulators

A Schanz screw can be inserted percutaneously into a large bony fragment and used as a manipulator to facilitate fracture reduction. Large threaded pins with holders are also available for the same purpose. Once appropriate reduction is achieved, the Schanz screws or manipulators can be connected by external fi xator tubes and clamps to hold the reduction in place. Push–pull technique

This technique is used to adjust length after preliminary fi xation of the fracture. A tension device applied to the end of the plate can be used to distract the fracture site to gain length (Fig | Anim 7-6). The plate is fi rst fi xed temporarily with a screw distally to ensure that the plate is positioned correctly before attachment of the tension device. The screw is removed before distraction is carried out. If desired, the tension device can be used to apply compression once the fracture has been reduced. Reduction by implants

Fig 7-5 formity.

A supporting pad can be used to correct a recurvatum de-

Fixed angled devices and anatomically shaped implants can be used as aids for fracture reduction. First, the articular block is fi xed to the plate. Standard cortex screws may be applied to pull the articular block to the plate. Once the reduction is achieved under fluoroscopic guidance, fi xation of the articular block is completed using additional standard or locking head screws (LHS), depending on the type of implant used. Next, the metaphyseal and diaphyseal components of the fracture are reduced to the articular block and the plate. If necessary, a cortex screw can again be used as an aid to pull the bone toward the plate (reduction screw). With certain types of plate

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Animation

a

b

c

Fig | Anim 7-6a–c a

Introduction of the condylar plate 95º, insertion of the screw proximally, and temporary monocortical screw fi xation distally to pull the bone to the plate.

b

Use of the tension device to distract the fracture to gain length in order to allow fracture reduction. The tempo-

c

If desired, the tension device can then be used to apply compression after reversing the direction of its hook.

rary fi xation screw at the distal end of the plate must fi rst be removed to allow the distraction to take place.

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7

Reduction techniques

such as the LISS, it is possible to use a special pull-reduction instrument which is placed through an insertion guide and plate hole to pull or push bone fragments in relation to the plate. Minor degrees of varus-valgus or translational malalign-

ment can be corrected using this device. When proper alignment of the articular and diaphyseal components of the fracture has been confi rmed, fi xation to the diaphyseal bone can be completed (Fig | Anim 7-7).

Animation

a

b

c

d

4 5 2 Fig | Anim 7-7a–f 3

a

1 6

b–e After incision, the metaphyseal fragment is fi xed temporarily to the plate

Anatomically shaped implants provide guidance for reduction. first, and position is confirmed under image intensifier before definitive fi xation with a cortex screw (reduction screw).

f e

f

The fi xation to the diaphyseal bone should then be completed in sequence (1–6), according to the preoperative plan.

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An LCP can also be used as a reduction tool. However, the plate must fi rst be contoured according to the anatomy of the bone, and then reduction and fi xation is carried out as described above. When using an LCP that has not been accurately precontoured, it is essential that an acceptable reduction is obtained before the application of LHS. A poorly reduced fracture will be fi xed in a poor position with LHS as these will not allow any collapse of the fracture after fi xation (Fig | Anim 7-8).

4.2.2

Direct reduction

Occasionally, the quality of indirect fracture reduction in diaphyseal fractures may be inadequate. It may then be necessary to perform direct reduction through small incisions in order to achieve the accuracy of reduction necessary to restore form and function after fracture fi xation and union. Simple fractures requiring anatomical reduction and stable fi xation for direct bone healing, displaced long oblique or spiral fractures, and widely separated large wedge fragments are examples of fractures which may benefit from direct reduction if indirect methods prove unsuccessful. Even with direct open reductions, it is important to bear in mind the importance of preservation of biology so that soft-tissue dissection and stripping is kept to the minimum. The instruments used should therefore be consistent with this principle and only cause minimal soft-tissue disruption. During open surgery, pointed reduction forceps should be used instead of reduction clamps which compress the periosteum. In transverse and short oblique fractures, a small Hohmann retractor inserted between the fracture ends as a lever is quite helpful for reduction. A large pelvic reduction clamp is useful in fractures around the knee and ankle. Collinear reduction forceps, with different arms for the diaphyseal and periarticular segments, are available and facilitate fracture reduction with minimal exposure of the fracture site.

Animation

a

b

Fig | Anim 7-8a–b a

The bone is gradually pulled toward the plate when standard cortex screws are inserted.

b

Angular stability of the LHS ensures maintenance of the initial reduction (= no loss of secondary reduction). Exact contouring is not necessary as the fracture is not reduced to the plate (= no loss of primary reduction). This is an advantage when the plate is used in conjunction with LHS in MIPO surgery.

Cerclage wires

Cerclage wiring can be helpful in reducing a large wedge fragment or an oblique or spiral fracture which is severely displaced and may cause delay in bone healing. This technique has the advantage of minimal denuding of the bone fragment. Insertion of the wirepasser should be done carefully with minimal stripping of the soft tissue around the fracture. Such wires may be temporary and removed immediately after the preliminary fi xation, or they may be left in place when an internal fi xator type of plate is used to fi x the fracture and there is a gap between the bone and the implant (Fig 7-9).

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7

Reduction techniques

b

a Fig 7-9a–c

c

Cerclage wiring can be helpful in reducing a large wedge fragment that is

severely displaced and may cause delay in bone healing. In fracture fi xation with an internal fi xator, such wires can be left in place if there is a gap between the bone and the implant.

5

Summary

In general, the modern trauma surgeon should be familiar with the different reduction techniques, ranging from direct and open manipulation to indirect and closed means. The choice of reduction technique should be made at the time of preoperative planning. If a closed and indirect reduction is not adequate, then one can choose to use an open and direct method of reduction. Even with direct methods, there exists a variety of reduction aids and tools which minimize intraoperative trauma to the soft tissue surrounding the fracture. The key is to leave a small foot print, or the least possible damage, at the fracture zone.

6

Suggested reading

Kregor PJ, Stannard J, Zlowodzki M, et al (2001) Distal femoral fracture fi xation utilizing the Less Invasive Stabilization System (L.I.S.S.): the technique and early results. Injury; 32 Suppl 3:32–47. Krettek C, Miclau T, Grun O, et al (1998) Intraoperative control of axes, rotation and length in femoral and tibial fractures. Technical note. Injury; 29 Suppl 3:29–39. Mast J, Jakob R, Ganz R (1989) Planning and Reduction Technique in Fracture Surgery. 1st ed. Berlin Heidelberg New York: Springer-Verlag. Müller ME, Allgöwer M, Schneider R, et al (1991) Manual of Internal Fixation. 3rd ed. Berlin Heidelberg New York: Springer-Verlag. Rüedi TP, Murphy WM (2001) AO Principles of Fracture Management. Stuttgart New York: Georg Thieme Verlag.

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8

Decision making and preoperative planning

1

Introduction

79

2

Planning in MIPO

79

3

Patient evaluation

79

12

Examples of cases with preoperative planning and the results 85

12.1

Tibia and fibula, proximal: complete articular fracture, articular multifragmentary—41-C3

12.2

4

Fracture evaluation

79

5

Graphic preoperative plan

80

5.1

Direct overlay

80

5.2

Overlay using the normal side

80

5.3

Use of physiological axes for articular fractures 80

6

Implants

81

6.1

Type of plate

81

6.2

Plate function

81

6.3

Plate length

81

6.4

Number of screws

81

6.5

Type of screw

82

6.6

Order of screw insertion

82

6.7

Plate position

82

6.8

Plate contouring

82

7

Reduction techniques

83

8

Timing of surgery

83

9

Control of axes, rotation, and length during MIPO

83

10

Preparing the OR

83

11

Alternative surgical tactic

84

85

Tibia and fibula, distal: complete articular fracture, articular simple, metaphyseal, multifragmentary—43-C2

12.3

13

87

Tibia and fibula, distal: complete articular fracture, articular multifragmentary—43-C3

89

Suggested reading

91

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Author

8 1

Tadashi TANAKA

Decision making and preoperative planning Introduction

Preoperative planning has always been an important component of the overall strategy of operative fracture care in the AO philosophy. Preoperative planning allows the surgeon to perform the operation in his mind before the actual surgical procedure. It gives him an opportunity to prepare the equipment that might be required, and enables him to plan the steps of the operation, including the location of the incisions, reduction technique, choice of implants, and techniques of application. With preoperative planning the surgeon is better prepared for surgery, thus ensuring a higher chance of success and avoiding possible complications. Another advantage is that the surgeon can provide the patient with a detailed explanation of the operation so that he can obtain informed consent and ensure a good patient–surgeon relationship.

2

Planning in MIPO

In MIPO, preoperative planning plays an even more significant role. Since the fracture sites are not exposed or visualized, the surgeon must plan each step of the surgical procedure to ensure that the operation proceeds smoothly, precious time is not wasted, and that unnecessary exposure to irradiation is avoided.

3

Patient evaluation

Proper assessment of the patient and the injury is necessary for correct decision making. This includes a detailed history, a careful physical examination, relevant laboratory tests, x-rays, and other ancillary imaging studies if indicated. Patient factors that need to be considered in the decisionmaking process include: Age Occupation General medical status and comorbidities Posttrauma status including hemodynamic stability Bone quality Preinjury functional status Patient compliance Future expectations This evaluation helps to decide whether the patient is a suitable candidate for surgery and is fit for anesthesia.

4

Fracture evaluation

For proper assessment of the fracture, good quality x-rays are required. Traction fi lms are useful in some instances. Other imaging studies that may be helpful include CT scans, 3-D reconstructions, MRI and vascular studies.

The following guidelines may be helpful in the decisionmaking process and preparation of a preoperative plan for MIPO.

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The fracture factors that should be taken into consideration include: Duration after injury Closed or open fracture Location—articular, metaphyseal, or diaphyseal Simple, wedge, or complex Condition of the skin and soft tissues Neurovascular injuries Associated fractures Associated injuries Good indications for MIPO include complex or multifragmentary fractures of the diaphysis and metaphysis and intraarticular fractures with extension into the diaphysis. Relative indications include simple diaphyseal fractures and certain open fractures.

Relevant implant templates of the correct scale A goniometer Colored felt-tipped pens and pencils The following planning techniques are commonly used: Direct overlay Overlay using the normal side Use of the physiological axes for articular fractures 5.1

This technique is usually used for diaphyseal fractures. Each fragment is traced onto a separate tracing paper. The bone is then rebuilt by gathering the fragments in a straight line, implying the central axis of the bone, followed by application of the appropriate implant template to draw the implant in an optimal position. 5.2

5

Graphic preoperative plan

One of the requirements of a good preoperative plan is to prepare a graphic representation of the fracture fragments, manipulating the fragments on paper to achieve a reduction, selecting the appropriate implants and superimposing them on the reduced fracture using templates, and reviewing the plan to see whether the desired end result is achieved. To prepare a graphic preoperative plan, the following are essential: X-rays of good quality, including views of the normal side if possible Additional imaging such as CT scans (especially for intraarticular fractures) Tracing paper (or transparencies)

Direct overlay

Overlay using the normal side

First, a tracing of the bone on the intact side is made and turned over. Then the fracture fragments are drawn separately and reassembled onto the drawing of the intact side. A template of the planned implant is superimposed to decide its correct location (Fig 8-2, Fig 8-3, Fig 8-4). 5.3

Use of physiological axes for articular fractures

Using a template or the x-rays of the opposite side, an outline of a physiological axis is drawn. Next the articular fragments are drawn in, respecting the physiological axis. Additional metaphyseal or diaphyseal fragments are also reassembled around the axis. Preoperative planning for articular fractures differs somewhat from diaphyseal fractures.

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8

Decision making and preoperative planning

For articular fractures, anatomical reduction of each fragment and stable fi xation with lag screws are vital to achieve a congruent joint surface. In this respect, CT scans are very useful to decide the direction of the lag screws, facilitating their insertion in the actual operation (Fig 8-8, Fig 8-12).

As MIPO is most often used for multifragmentary or complex diaphyseal fractures, the plate is commonly applied as a splint in the bridging mode.

In the case of multifragmentary diaphyseal fractures, the aim of surgery is to restore the correct length, alignment, and rotation of the bone rather than the anatomical reduction of the fracture fragments. Nevertheless, drawing in the anatomically reduced fragments in the preoperative plan helps selecting the appropriate plate and screws.

The selection of the appropriate length of the plate is a very important step in the preoperative plan. The length depends on the fracture pattern and the function that the plate is intended to serve.

6

Implants

The following factors should be considered in selecting the appropriate type of implant to be used in the MIPO procedure. 6.1

Type of plate

The types of plate used in MIPO include: Conventional plates (DCP or LC-DCP) or locking compression plates (LCP) Fixed angle implants Special anatomically preshaped plates 6.2

Plate function

The plate may function as a: Internal fi xator Bridging plate Compression plate Buttress plate Neutralization plate A combination of the above

6.3

Plate length

Two values have been used to determine the length of the plate to be used (Chapter 14 Femur, shaft: Fig 14-7): Plate span ratio The plate span ratio is the quotient of the plate length and overall fracture length. Empirically, the plate span ratio should be more than 2–3 in multifragmentary fractures and more than 8–10 in simple fractures. Plate-screw density The plate-screw density is the quotient formed by the number of screws inserted and the number of plate holes. Empirically, values below 0.5–0.4 have been recommended. This means that fewer than half of the plate holes should be occupied by screws. In general, the longest possible plates should be used since the longer the plate, the more stable and effective it is as a splint. There is no advantage in using shorter plates in MIPO since plates of all lengths are inserted through the same sized incisions. 6.4

Number of screws

The number and location of screws will depend on the biomechanical concept chosen and is described in detail in Chapter 2 (Mechanobiology). Basically two screws in each main fragment are the minimal number required to maintain 81

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the bone–implant construct from a purely mechanical point of view. However, loosening of one screw will cause overloading of the other screw, resulting in failure of the whole construct. It is generally recommended to use three screws in each main fragment in order to secure the fi xation. The number may, of course, be decreased for anatomical reasons (epi-/metaphyseal regions), and increased because of poor bone quality (osteoporosis). 6.5

Type of screw

Standard screws (cortex screws or cancellous bone screws) are used with conventional plates. With the LCP, four different types of screw can be used: Standard cortex screw Standard cancellous bone screw Self-tapping locking head screw Self-drilling and self-tapping locking head screw Standard screws are recommended in the following situations: When a screw needs to be inserted at an angle to avoid joint penetration. To apply compression, either as a lag screw for interfragmentary compression, or for eccentric screw insertion in the dynamic compression half of the combination hole of the LCP to achieve axial compression. As a reduction aid to draw the fracture fragments to the plate. For preliminary stabilization of the plate on the bone before the application of locking head screws (LHS). Self-tapping LHS are used for bicortical insertion when angular stability is required, especially in osteoporotic bones.

Self-drilling, self-tapping LHS are mainly used monocortically in the diaphyseal segment of bone in cases with excellent bone quality. They are also used when fi xing periprosthetic fractures. 6.6

Order of screw insertion

The order of screw insertion depends on the intended function of the plate and should be decided preferably during preoperative planning. Usually, the screw at the proximal end of the plate is inserted fi rst. The fracture is then reduced if it has not already been done and the screw at the distal end of the plate is next inserted. The quality of the fracture reduction is checked and, if satisfactory, the remaining screws are inserted according to the preoperative plan. If both standard screw and LHS are used in the same LCP, it is recommended to insert fi rst the standard screws. If the plate has been fi xed initially to the bone with LHS, and subsequent insertion of standard screws is needed, the LHS must be loosened before the standard screws are inserted. 6.7

Plate position

Since the implants are inserted without exposure of the bone or soft tissue, it is important to select a position for the plate that will avoid injuring any vital structure such as a major vessel or nerve during its insertion. 6.8

Plate contouring

Depending on the implant selected and the location and pattern of the fracture, it is often necessary to contour the plate. This is especially required when using conventional plates, in order to avoid malreduction of the fracture. Since the fracture site is not exposed in MIPO, plate contouring using templates

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8

Decision making and preoperative planning

is not possible. The contouring therefore needs to be done preoperatively, usually with the aid of plastic bone models or x-rays. The contoured plate is then sterilized for the operation. Fine adjustments of the plate contour may be done intraoperatively if necessary. An alternative would be to use special anatomically preshaped plates if available.

7

Reduction techniques

Indirect fracture reduction is used in MIPO. The method of indirect reduction should be planned so that the necessary equipment and manpower are available at the time of surgery. Once fracture reduction is achieved, the method of maintaining the reduction, such as with the use of the large distractor or external fi xator, should also be prepared.

9

In MIPO of multifragmentary diaphyseal fractures, the fracture is not exposed and anatomical reduction of the fracture fragments is not required. It is therefore difficult to judge whether the fracture is adequately reduced to the correct axes, rotation, and length of the limb during surgery, especially as the opposite limb is often covered with drapes and hence not available for comparison. Several methods, both clinical and radiographic, are available to check limb alignment and length (Chapter 10 Complications and solutions). These often have to be verified before the start of the operation. The surgeon should be familiar with these methods and prepare ahead so that during surgery obtaining satisfactory reduction can be checked.

10 8

Timing of surgery

If the condition of the soft tissue permits, MIPO should be carried out as soon as feasible. Otherwise, it would be better to delay the surgery until the soft-tissue condition is favorable. In the meantime, temporary immobilization with splinting, external fi xation, or traction may be required. The delay, however, should not be too long, as fracture reduction and correction of limb alignment and length become increasingly more difficult with time, and the surgery would become more invasive, technically difficult, and time-consuming.

Control of axes, rotation, and length during MIPO

Preparing the OR

To ensure that the operation proceeds according to plan, the OR must be adequately prepared. Planning for the OR should include: The correct operating table—traction or radiolucent Type of anesthesia Patient position Use of tourniquet Image intensifier Availability of the correct instruments and implants A good surgical team

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11

Alternative surgical tactic

Despite adequate preparations, there are occasions when surgery does not proceed according to plan and technical difficulties are encountered. When such a situation arises, the surgeon must be prepared to abandon the original plan and proceed with another method of treatment such as open reduction or switch to another type of fi xation device. A well-performed conventional open fracture fi xation is much better than a poorly executed MIPO with its attendant complications.

84

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8

12

12.1

Decision making and preoperative planning

Examples of cases with preoperative planning and the results

Tibia and fibula, proximal: complete articular fracture, articular multifragmentary—41-C3; 36-year-old male

Technique of the preoperative planning

a

b

Fig 8-1a–b

Fig 8-2

1. The intact side is traced and turned over (Fig 8-2). 2. Each fracture fragment is traced out (Fig 8-3) and superimposed on to the tracing of the intact side. 3. A template of the planned implant is superimposed and the location as well as the order of insertion of the screws is noted (Fig 8-4).

Preoperative x-rays (AP and lateral).

Drawings of the intact side (AP and lateral).

Fig 8-3

Drawings of the fragments from the injured side (AP and

lateral).

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12.1

Tibia and fibula, proximal: complete articular fracture, articular multifragmentary—41-C3; 36-year-old male

Surgical steps (Fig 8-4)

1

1

2, 5

Lag screw fi xation of articular fragments using 3.5 mm cortex screws.

4

2

A 9-hole lateral tibial buttress plate is used. The proximal part of the plate is fi xed with a 6.5 mm partially threaded cancellous bone screw. The most distal screw is then inserted.

4

Lag screw fi xation in the anteroposterior direction.

5

6

Other holes in the proximal part are filled with 6.5 mm partially threaded cancellous bone screws.

3

Fig 8-4

3

6

Two more screws are inserted in the distal holes.

Drawings of planned reduction and fi xation (AP and lateral).

a Fig 8-5a–b

b Postoperative x-rays (AP and lateral).

a

b

Fig 8-6a–b Follow-up x-rays; 13 months after MIPO (AP and lateral).

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8

12.2

Decision making and preoperative planning

Tibia and fibula, distal: complete articular fracture, articular simple, metaphyseal, multifragmentary—43-C2; 39-year-old female

a

b

Fig 8-7a–c

c

Preoperative x-rays (AP, lateral, and CT).

Surgical steps (Fig 8-8) 6

1

Lag screw fi xation of fibular fracture.

2

Fixation of distal fibula with an 8-hole one-third tubular plate used as neutralization plate.

8

3

After reduction of joint surface, lag screw is inserted from anterior to posterior. The direction is easily estimated by CT scan.

2

1

4

Contour a 9-hole LCP (bending and twisting). Check the location of the plate so as to secure an adequate length of the

9

most distal screw. Do not insert screw at this stage (an LHS is

5

to be used).

4, 7

3

5

Lag screw fi xation for the distal fracture to reduce the distal fragment against the plate (reduction screw).

From this stage on, the LHS are inserted: Fig 8-8 and CT).

Drawings of planned reduction and fi xation (AP, lateral,

6

Screw fi xation for the most proximal hole.

7

Screw fi xation for the most distal hole.

8

Two other screws are inserted in the proximal part.

9

One more screw is inserted in the distal part.

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12.2

Tibia and fibula, distal: complete articular fracture, articular simple, metaphyseal, multifragmentary—43-C2; 39-year-old female

a

b

c

Fig 8-9a–c a

Skin incision.

b–c

Postoperative x-rays (AP, lateral).

a Fig 8-10a–b

b Follow-up x-rays; 16 months after MIPO (AP and lateral).

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8

12.3

Decision making and preoperative planning

Tibia and fibula, distal: complete articular fracture, articular multifragmentary—43-C3; 56-year-old male

c

a

b

Fig 8-11a–d

d

Preoperative x-rays (AP, lateral, and CT scans).

Surgical steps (Fig 8-12) 1

Bridge plating for the fibular fracture.

2

First, the articular fragments are anatomically reduced and then temporarily fi xed with K-wires. Lag screw fi xation is then carried out using a 3.5 mm cortex screw in an anterior-

1

posterior direction. CT scan easily guides the direction.

5

3

Another lag screw is inserted proximally.

4

The articular block is connected with the diaphysis in

3

anatomical alignment. After the level of the plate is checked, one of the distal screws is inserted.

4

5 2

Fig 8-12

Check the alignment of the bone and the plate, then insert the screws in the proximal fragment. All other screws are inserted.

Drawings of planned reduction and fi xation (AP, lateral,

and CT scan).

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12.3

Tibia and fibula, distal: complete articular fracture, articular multifragmentary—43-C3; 56-year-old male

a

b

c

Fig 8-13a–c a

Intraoperative picture. MIPO is feasible even in the presence of an unhealed wound, which is a contraindication for conventional plating.

b–c Postoperative x-rays (AP, lateral).

a Fig 8-14a–b

b Follow-up x-rays; 9 months after MIPO (AP and lateral).

90

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8

Decision making and preoperative planning

91

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9

Postoperative management

1

Introduction

93

2

Analgesics

93

3

Antibiotic prophylaxis

93

4

Thromboembolism

94

4.1

Risk factors

94

4.2

Prophylaxis

94

4.3

Diagnosis

94

4.4

Treatment of deep vein thrombosis (DVT)

95

5

Wound care and drains

95

5.1

Wounds

95

5.2

Drains

95

6

Positioning and support of the affected limb

95

7

Mobilization and weight bearing

97

8

Postoperative x-ray examination

97

9

Discharge and follow-up observation

97

10

Implant removal

98

11

Suggested reading

99

92

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Authors

9 1

Tadashi TANAKA, Toru SATO

Postoperative management Introduction

In MIPO, the degree of analgesia required is usually less and of shorter duration because of the smaller wounds and lesser degrees of soft-tissue dissection.

In order to ensure a successful outcome in the operative treatment of fractures, a well-managed postoperative program is indispensable, as is a good preoperative plan and a carefully executed operation. Postoperative management should in principle aim at the prevention of fracture disease. Early mobilization helps to prevent joint contracture and disuse atrophy of the muscles. To realize this aim, the stability imparted to the fracture following the MIPO procedure must be adequate, otherwise the purpose of the fracture fi xation will be lost. The following factors must be taken into consideration for successful postoperative management.

2

Analgesics

Adequate analgesia reduces postoperative pain and increases patient comfort. This would encourage the patient to cooperate effectively in the postoperative rehabilitation program. In general, analgesics should be started well before pain becomes unbearable. Commonly used methods of analgesia include: Local anesthetic infi ltration around the surgical wounds Epidural analgesia Suppositories Intravenous/intramuscular injections Patient controlled analgesia (PCA) pump Oral analgesic agents

Analgesics should be started well before pain becomes unbearable.

3

Antibiotic prophylaxis

By its nature, MIPO limits soft-tissue exposure and dissection. This in turn reduces the risks of wound infection. Nevertheless, it is generally accepted that prophylactic antibiotics should be administered in implant surgery. The following points should be considered when using prophylactic antibiotics: It has been shown that Staphylococcus aureus is the most common infective agent in implant-associated bone infection. The prophylactic antibiotic used should therefore be sensitive against Staphylococcus aureus, taking into consideration the resistance pattern of the organisms in the hospital. First or second generation cephalosporins are generally suitable. The choice of antibiotic should also take into consideration its potential adverse effects on the patient as well as the patient’s history of drug allergy. The antibiotic should be administered intravenously within 1 hour of the start of the operation in order to obtain adequate inhibitory antibiotic levels in the surgical site. The usual practice is to administer the antibiotic at the time of induction of anesthesia. If a tourniquet is used, at least 10 minutes should be allowed between antibiotic administration and tourniquet inflation.

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The antibiotic may be administered as a single preoperative dose or over the course of 24 hours. There is no advantage in prolonging the prophylaxis beyond 1 day. The use of prophylactic antibiotics does not preclude the occurrence of wound infection. The surgeon must be aware of the symptoms and signs as well as the laboratory markers of wound infection and institute the appropriate treatment as soon as possible. Antibiotics should be administered as close as possible to the time of skin incision.

4

Thromboembolism

Venous thromboembolism constitutes an important cause of postoperative morbidity and mortality in orthopedic traumatology. It is therefore incumbent on the part of the surgeon to be familiar with the risk factors, preventive measures, diagnostic tests, and treatment strategies for this potentially fatal complication. 4.1

Pregnancy Estrogen use Fractures of the pelvis, proximal femur, and around the knee Multiple trauma 4.2

Prophylaxis

Thromboembolic prophylaxis, combined with efficient surgery and early mobilization, has been shown to have a lower risk of fatal pulmonary embolism. Thromboembolic prophylaxis should begin prior to or just after surgical intervention and should be continued for at least 10 days or, in the case of high-risk patients, for as long as 5 weeks. The common methods of prophylaxis include: Pharmacological agents, eg, warfarin, low-molecular-weight heparin, low-dose unfractionated heparin, fondaparinux, and acetylsalicylic acid. Mechanical devices, eg, external pneumatic compression boots and graduated compression stockings. Combined use of mechanical devices and pharmacological anticoagulant agents.

Risk factors

Important risk factors include: Advanced age History of previous venous thromboembolism Strong family history of thromboembolism History of cancer, myocardial infarction, congestive heart failure, chronic obstructive pulmonary disease, cerebrovascular accident (CVA) or paralysis Prolonged bed rest or delayed mobilization Obesity

Thromboembolic prophylaxis in the posttrauma patient can be difficult and a balance has to be made between the risks and benefits of the various methods. 4.3

Diagnosis

Constant vigilance is necessary for early diagnosis and treatment of deep vein thrombosis (DVT). Clinical signs such as calf swelling and tenderness or a positive Homans’ sign are neither specific nor reliable.

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9

Postoperative management

The following diagnostic tests are more accurate: Ascending venography Duplex ultrasonography Magnetic resonance venography

5.2

Drains are usually not required after MIPO of diaphyseal fractures. Drainage may be necessary when a joint is opened in articular fractures. When used, drains should preferably not be retained for longer than 48 hours unless there is copious drainage.

Of the three, magnetic resonance venography is the most reliable for detecting pelvic thromboses, which carry the highest risk of pulmonary embolism. 4.4

Treatment of deep vein thrombosis (DVT)

Once a diagnosis of DVT is made, a decision must be made whether treatment should be started or close surveillance continued. In general, clots proximal to the popliteal vessels should be treated because of the higher risk of embolization, whereas serial surveillance of calf DVT is reasonable as it does not usually propagate or embolize. Treatment of established thrombi includes the use of heparin, warfarin and inferior vena cava fi lters.

5

5.1

Drains

6

Positioning and support of the affected limb

Elevation helps to reduce swelling which can impede postoperative rehabilitation (Fig 9-1). Avoid pressure where nerves are vulnerable, eg, ulnar nerve at the medial humeral epicondyle and peroneal nerve over the fibular head. Judicious use of splints can prevent malpositions, eg, splinting the forearm and hand in the “intrinsic-plus” position helps to prevent fi nger contractures, and applying a U-slab to the foot can help prevent equinus deformity.

Wound care and drains

Wounds

In contrast to conventional osteosynthesis, the surgical wounds in MIPO are small. Nevertheless, they need proper attention. Wounds should be kept clean and dry. Soaked dressings need to be changed. If nonabsorbable suture materials are used, stitches should be removed after 12–14 days.

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a

b

Fig 9-1a–c

To reduce swelling, the affected limb is lifted above the

level of the heart.

c

a

Upper extremity.

b

Distal/midshaft femur.

c

Lower leg.

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9

7

Postoperative management

Physical therapy should start as soon as feasible following MIPO. Joints should be mobilized by active or active-assisted movements. Continuous passive motion may be helpful initially in restoring joint motion, especially after fi xation of articular fractures. In lower limb fractures, depending on the bone quality, stability of the fi xation and fitness of the patient, nonweight bearing or partial weight bearing (10–15 kg) walking exercises should be started early. Hydrotherapy is a useful way of providing relatively weightless and pain-free mobilization. Weight bearing up to 10–15 kg is started immediately after surgery.

8

was applied. Direct bone healing without callus is to be expected after interfragmental compression while indirect healing with callus formation is the norm after splinting using the bridging plate principle, which is usually the case after MIPO.

Mobilization and weight bearing

Postoperative x-ray examination

X-rays should be taken at the conclusion of the MIPO procedure or early in the postoperative period to document the quality of fracture reduction and fi xation. Thereafter, x-rays are repeated at 4–6 week intervals to monitor the progress of fracture union and to detect any evidence of implant loosening or breakage so that the appropriate remedial measures can be undertaken as soon as possible. It is important to remember that the follow-up radiographic fi ndings are closely related to the type of stabilization that

The radiographic findings are closely related to the chosen type of stabilization. If there are abnormal findings, one must change the postoperative care accordingly.

9

Discharge and follow-up observation

The patient is ready for discharge from hospital when the following conditions are fulfi lled: Postoperative x-rays are satisfactory. There is no symptom or sign of infection. The patient understands the purpose of his rehabilitation program and is able to comply. The patient is aware of what has been done and the possible complications that may arise. Post-discharge care providers are briefed on the aftercare program. Arrangements are made for further follow-up. Following discharge from hospital, the patient should be reviewed regularly to monitor the state of fracture healing, the progress made in rehabilitation, and any complication that might occur. Corrective action is taken as and when necessary. As the fracture heals, weight bearing is accordingly increased and the patient is encouraged to gradually resume work and his normal activities.

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10

Implant removal

For most patients, treatment is regarded as being completed when the implants are removed. Implant removal should only be undertaken after fracture healing is completed, usually after 1–2 years. Not all implants need removal. The disadvantages of implant removal include risks of anesthesia, infection, neurovascular injury, refracture, and additional cost. The incidence of refracture after removal of implants is considered lower after MIPO as compared to conventional compression plating, but no conclusive evidence has been obtained. Implant removal may be considered under the following circumstances: Young patient When the implant is in the lower limb When the implant is causing inhibition of limb function or irritation of the adjacent structures In the presence of infection. If stable, the implant may be left in place until fracture union occurs before it is removed.

To remove an implant in a case following MIPO, the screws are fi rst removed through the original skin incisions and the plate is then detached from the bone using an elevator inserted between them. If the plate cannot be removed by this method, a skin incision is made along the entire length of the plate (open method). Prior to the surgery, the patient should be informed that it is not always possible to remove all the implants. If there are broken screws, one should confi rm whether the patient wishes to have them removed. In general, broken screw residuals left in the bone need not be removed unless they protrude from the bone surface causing discomfort to the patient. It should also be noted that there are instruments for removal of damaged screws, consisting of special drill bits and conical extraction screws. The possibility of refracture following implant removal must always be borne in mind. The onset of pain following strenuous activities may indicate that refracture has occurred. To avoid this, the patient should be advised to avoid contact sports or heavy physical labor for 2–4 months after implant removal.

When implant removal is planned, it is necessary to inform the patient of the potential complications of its removal.

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9

11

Postoperative management

Suggested reading

Gatell JM, Garcia S, Lozano L, et al (1987) Perioperative cefamandole prophylaxis against infections. J Bone Joint Surg [Am]; 69(8):1189–1193. Geerts WH, Pineo GF, Heit JA, Bergqvist D, et al (2004) Prevention of venous thromboembolism. the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest; 126:338S–400S. Kaiser AB (1986) Antimicrobial prophylaxis in surgery. N Engl J Med; 315(18):1129–1138. Review. Siddiqui AU, Buchman TG, Hotchkiss RS (2000) Pulmonary embolism as a consequence of applying sequential compression device on legs in a patient asymptomatic of deep vein thrombosis. Anesthesiology; 92(3):880–882. Warwick D, Harrison J, Glew D, et al (1998) Comparison of the use of a foot pump with the use of low-molecular-weight heparin for the prevention of deep-vein thrombosis after total hip replacement. A prospective, randomized trial. J Bone Joint Surg [Am]; 80:1158–1166. Wells PS, Lensing AW, Hirsh J (1994) Graduated compression stocking in the prevention of postoperative venous thromboembolism. A meta-analysis. Arch Intern Med; 154:67–72.

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Complications and solutions

1

Introduction

101

2

Malalignment—prevention and correction

101

Malrotation

101

2.1

2.2

2.3

2.1.1

Femur

2.1.2

Tibia

Varus–valgus malalignment 2.2.1

Femur

2.2.2

Tibia

AP angulation: sagittal plane malalignment 2.3.1

Femur

2.3.2

Tibia

105

107

3

Limb length discrepancy

109

3.1

Prevention of shortening

110

4

Neurovascular injuries

110

4.1

Humerus

110

4.2

Femur

111

4.3

Tibia

111

5

Early postoperative complication

112

5.1

Infection

112

6

Late postoperative complications

114

6.1

Implant failure

114

6.2

Delayed union

114

7

Suggested reading

118

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Author

10 1

Theerachai APIVATTHAKAKUL

Complications and solutions Introduction

As in conventional plating, minimally invasive plate osteosynthesis (MIPO) is associated with complications. However, the complications encountered are somewhat different from those of conventional plating. Because in MIPO, the fracture sites are not exposed during reduction and plate application, malrotation, axial malalignment, and limb length discrepancy become more common, while infection, delayed and nonunion, and hence implant failure, are less frequent by virtue of the preservation of biology at the fracture site that is inherent in the MIPO technique. In order to reduce the occurrence of malrotation, axial malalignment, and limb length discrepancy, the following strategies are helpful: Always be mindful of the possibility of these complications occurring. Be familiar with the various methods of detecting their occurrence. Be familiar with the common pitfalls and the best ways of prevention.

In general, the complications in MIPO may be divided into three phases: Intraoperative complications: rotational and axial malalignment, limb length discrepancy, and neurovascular injuries Early postoperative complication: acute infection Late postoperative complications: implant failure, delayed union, and nonunion

2

2.1

Malrotation

This complication commonly occurs in MIPO, but is often overlooked as it is not always obvious in plain x-rays. Gross malrotation can be recognized clinically, but lesser degrees are more difficult to detect. Hence it is important to be familiar with the various methods of evaluating rotational deformities and the steps necessary to prevent their occurrence. 2.1.1

Even with the best efforts complications do sometimes occur. When that happens, it is essential that they are discovered and corrected early, preferably intraoperatively, or, if that is not possible, within 2 weeks, and certainly before fracture union takes place. Correction becomes much more difficult and complicated once malunion has occurred and especially if adaptive changes in the anatomy have taken place.

Malalignment—prevention and correction

Femur

In the femur, malrotation occurs most commonly with proximal femoral and subtrochanteric fractures. The deforming forces of the iliopsoas, gluteus medius, and short external rotators pull the proximal fragment into flexion, abduction, and external rotation, respectively. Performing fracture reduction and fi xation without concern for these deforming forces will lead to malreduction, including malrotation (see Fig 10-5).

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There are several intraoperative methods of assessing whether a proximal femoral fracture is fi xed in the correct rotational alignment. These methods may be clinical or radiological: Hip rotation test (Fig 10-1) The lesser trochanter shape sign (Fig 10-2) The cortical step sign (Fig 10-3) The diameter difference sign (Fig 10-4) The hip rotation test is a clinical method that compares hip rotation with that of the contralateral unaffected side. This technique is easily performed and it is radiation-independent. However, the clinical judgment may be wrong, and it is also dependent on the position of the pelvis, which may change during the course of the operative procedure.

The hip rotation test cannot be used if the patient is on a traction table. In such cases, radiological methods of assessing rotation will have to be used. These include the lesser trochanter shape sign, cortical step sign, and diameter difference sign. For multifragmentary fractures of the proximal femur with an intact lesser trochanter, the lesser trochanter shape sign is most useful. When the lesser trochanter is fractured, the rotation should be assessed by clinical means. In simple transverse or oblique fractures, the correct rotation may be judged by the thickness of the cortices of the proximal and distal fragments (cortical step sign). The cortical step sign and the sign of diameter difference cannot be used in multifragmentary fractures as the area of comminution makes comparison of the cortical step and diameter impossible. In the midshaft and distal femur, the deforming forces are less, and malrotation is therefore less common. However, the rotation after fi xation still has to be checked intraoperatively, both clinically and radiographically.

Fig 10-1

The rotation of the femur can be checked by the hip rota-

tion test. Measure with the patient lying on his back, with hip and knee both flexed at 90º.

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10

Complications and solutions

Fig 10-3

Cortical step sign.

In the presence of a considerable rotational deformity, this can be diagnosed by the a

b

Fig 10-2a–d

c

d

difference in the thickness of the cortices.

The lesser trochanter shape sign: an intraoperative radiological assessment of

rotation in which the shape of the lesser trochanter is compared with that of the contralateral side. a

Before positioning the patient, the shape of the lesser trochanter of the intact opposite side (patella facing anteriorly) is stored in the image intensifier.

b

Before fi xing the second main fracture fragment, the patella is oriented anteriorly and the proximal fragment is rotated until the shape of the lesser trochanter on the ipsilateral side matches the shape of the contralateral lesser trochanter.

c

In cases of external malrotation the lesser trochanter is smaller and partially hidden behind the proximal femoral shaft.

d

In cases of internal malrotation the lesser trochanter appears enlarged. Fig 10-4

Diameter difference sign.

This sign is positive at levels where the bone cross-section is oval rather than round. With malrotation, the diameters of proximal and distal main fragments appear to be of different sizes.

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Case: femoral malrotation

a

b

c

d

e

Fig 10-5a–f a

A 40-year-old male fell from a height and sustained a multifragmentary subtrochanteric fracture of the right femur.

b

The fracture was stabilized with a 95º condylar blade plate by the MIPO technique using a traction table.

c

Postoperatively, the right lower extremity demonstrated internal malrotation deformity.

d

X-rays after revision of the distal screws and external rotation of the distal fragment.

f

e

Clinical result after revision of malrotation.

f

X-rays after 6 months show solid fracture union.

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10

Complications and solutions

Prevention of femoral malrotation

Bear in mind that this complication can occur and it is preventable. It is advisable to use a radiolucent operating table rather than a traction table. Although the traction table can maintain the length of the limb, the rotation cannot be assessed clinically during the operation. If the traction table is used, the lesser trochanter shape sign has to be used for comparison with the uninjured limb. If the radiolucent operating table is used, the rotation is checked after preliminary fi xation of both proximal and distal fragments by flexing the hip and knee to 90° (hip rotation test). Drape both lower limbs free if possible, to compare the rotation and to measure the length. Early revision or correction of any malrotational deformity is essential. It is much easier than correcting a malunited fracture as it is less time consuming and the patient can have early return to function. 2.1.2

Tibia

Malrotation of the tibia is easier to assess because there is less soft-tissue cover and the anteromedial surface of the tibia is easily palpated. Tibial rotation can be determined both clinically and radiographically by comparison with the uninjured limb. Clinical assessment of tibial rotation is performed by flexing the hip and knee to 90° while keeping the ankle dorsiflexed. The rotation of the tibia is then compared with the uninjured side by noting the position of the feet, as well as the range and symmetry of foot rotation. Rotational malalignment of the tibia occurs most commonly after MIPO of distal tibial fractures due to the peculiar anatomy of that part of the bone. The distal tibia is flared medially and the smooth anteromedial surface to which the plate is

applied twists posteriorly to end at the medial malleolus. This flare and twist must be taken into consideration when the plate is contoured, or it will result in malrotation and axial malalignment. Prevention of tibial malrotation

Precise plate contouring is necessary for MIPO of proximal and distal tibial fractures when using the DCP. The precontoured plate has to be placed in the correct position. Check the rotation of the tibia clinically by flexion of the hip and the knee to 90° while keeping the ankle dorsiflexed. 2.2

Varus–valgus malalignment

Frontal plane malalignment occurs more commonly in metaphyseal fractures. This is because the metaphyseal cortex is not straight as in the diaphysis. The plate thus needs to be precontoured or a precontoured anatomical plate may be used. For example, when the 95° condylar plate is used for fi xation of proximal or distal femoral fractures, and the blade is inserted in the correct position, indirect reduction of the shaft to the plate will usually provide correct frontal plane alignment. This concept can also be applied to the proximal and distal tibia using anatomically precontoured plates, such as the lateral tibial head buttress plate or the proximal lateral tibial LISS plate. An intraoperative technique for checking frontal plane malalignment of the lower extremity is the cable technique. In this technique, a cautery cable is spanned between the center of the femoral head and the center of the tibial plafond. The position of the cautery cable relative to the center of the knee joint under image intensification indicates the axial deviation in the frontal plane. This is a reliable method but it is radiationdependent (Fig 10-6). 105

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Animation

1

3

2

Fig 10-7

Cautery cord spans from anterior

superior iliac spine (ASIS) to the first web space.

Fig 10-6

Cautery cable technique using image intensifier for check-

2

In a similar way the center of the ankle joint is marked. An

ing alignment in the frontal plane: The knee is fully extended and the

assistant now spans the cautery cable between these two sur-

patella must face anteriorly.

face markings.

1

With the image intensifier beam strictly vertical, the center of the

3

When the knee joint is viewed with the image intensifier, the

femoral head is centered on the screen. A pen then marks the

cable should run centrally. Any deviation of the projected

center of the femoral head on the patient’s skin.

cautery cable from the center of the joint indicates the axial deviation in the frontal plane.

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10

Complications and solutions

A variation of the cable technique spans the cautery cable from the anterior superior iliac spine (ASIS) to the fi rst web space of the ipsilateral foot. If the frontal plane alignment is correct, the cable should pass through the center of the knee joint (Fig 10-7). This technique is easier but less precise and many errors can occur depending on the foot rotation, ankle position, and position of the hip in abduction or adduction. 2.2.1

Femur

When applying MIPO to fi x a proximal femoral fracture with a 95° condylar plate, varus malalignment can occur during plate insertion. The chiseled canal is fi rst prepared using standard AO techniques. The 95° condylar plate is then slipped into a submuscular tunnel alongside the lateral cortex of the femur with the blade pointing laterally. The blade is then turned medially for insertion into the prepared canal. However, the direction of the blade and canal frequently do not meet. The blade has a tendency to go in the wrong direction and create a false passage, resulting in the proximal fragment being fi xed in the varus position. The reason for this is that the lateral thigh muscles tend to push the blade plate into a varus position. This complication can be avoided by inserting a joystick into the proximal fragment to bring it into proper alignment to the blade during blade insertion (Chapter 13 Femur, proximal: Fig | Anim 13-11). Also, the guide pin used initially to guide the direction of the seating chisel should be left in place to guide the direction of blade insertion. Another useful tip is to use a short blade of 50–60 mm length which makes it easier to turn into the prepared canal. 2.2.2

then moved distally to take an AP view of the ankle joint. If the K-wire beneath the ankle joint is also parallel to the ankle joint line, there is no varus or valgus malalignment of the tibia (Chapter 17 Tibia and fibula, shaft: Fig 17-11). The unilateral external fi xator with the two Schanz screws constructed in parallel can also be applied using the same principle (Chapter 17 Tibia and fibula, shaft: Fig 17-12).

2.3

AP angulation: sagittal plane malalignment

2.3.1 Femur Femur, proximal

AP angulation at the proximal femur tends to occur with the 95° condylar plate which needs 3-D plate insertion. On the other hand, the dynamic condylar screw (DCS) needs only two dimensions, and any AP angulation is easily corrected by turning the plate–screw construct into the correct position to align with the femoral shaft. In proximal femoral fractures with the lesser trochanter attached to the proximal fragment, the proximal fragment has a tendency to go into flexion, abduction, and external rotation. Control of the proximal fragment into the normal AP and lateral position, as seen on the image intensifier, is necessary. A joystick is inserted into the proximal fragment and manipulated to counter the muscle pull. During chiseling of the blade canal and the subsequent insertion of the 95° condylar plate, the proximal fragment has to be kept in this position, or malalignment may occur.

Tibia

Varus or valgus malalignment of the tibia can be evaluated by using a tibial alignment grid which has multiple parallel K-wires 3–5 cm apart mounted between two plastic plates. The grid is placed beneath the tibia extending from the knee to the ankle. An AP view of the knee is taken with the image intensifier, with a K-wire parallel to the knee joint. The C-arm is

Femur, shaft

AP angulation at the diaphysis is directly controlled by lateral fluoroscopic guidance. To facilitate this, the operation should be performed with the patient in supine position on a radiolucent operating table, with a support under the thigh and the uninjured limb placed on a leg holder. 107

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Because the femur has an anterior bow, fi xation of a simple fracture with a long straight plate positioned on the center of the lateral cortex tends to produce some AP angulation at the fracture site. It is advisable to fi x the ends of the plate in the center of the lateral cortex, while the holes which are close to the fracture should be fi xed more posteriorly in order to reduce the fracture gap and avoid AP angulation of the fracture (Fig 10-8).

a

In multifragmentary fractures, the angulation at the fracture site is usually compensated by the multiple fragments and AP angulation at the fracture site is usually not a problem (Fig 10-9). Another technique to prevent AP angulation and to accommodate the anterior bow of the femoral shaft is to slightly bend a long plate into a convex shape to match the curve of the bone. This contoured plate is then positioned on the anterolateral cortex of the femur and fi xed with screws directed from an anterolateral to a posteromedial direction at about 30º–40º from the horizontal. One problem associated with correction of AP angulation is shortening of the bone due to overlapping of the fracture ends. In simple fractures, when the plate is fi xed temporarily with one screw in each fragment, the angulation can only be corrected if the fractured bone is of the correct length or slightly distracted. If there is overlapping of the fracture ends, it may not be possible to reduce the fracture back to the correct position.

b

Femur, distal c Fig 10-8a–c

Restoring the anterior bowing of the femur—an un-

favorable plate position can result in sagittal plane angulation. a

Fixing the proximal end of the plate too close to the posterior

The most common sagittal plane malalignment occurring after fi xation of fractures in the distal femur is posterior angulation. The distal fragment is usually displaced posteriorly by the pull of the gastrocnemius muscle. Flexion of knee up to 60º with a posterior support is necessary to relax the pull of

margin of the lateral cortex will result in anterior displacement of the distal end of the plate away from the bone. b

Fixing the whole length of the plate in the center of the lateral cortex will result in posterior angulation and loss of the anterior bowing.

c

It is advisable to fi x the ends of the plate in the center of the lateral cortex, and the holes which are close to the fracture should be fi xed more posteriorly to reduce the fracture gap and

Fig 10-9

avoid sagittal plane angulation.

chances of angulation at the fracture site.

Multiple fragments in comminuted fractures reduce the

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10

Complications and solutions

gastrocnemius. To manipulate the distal fragment into the correct position, a joystick is inserted into the anterior aspect of the distal femur, preferably in the extraarticular portion, and then rotated distally to realign the distal fragment to the proximal fragment (Chapter 7 Reduction techniques: Fig | Anim 7-3). The posterior cortex of the short distal fragment and the posterior cortex of the proximal fragment must be aligned. The lateral view is checked with the image intensifier. 2.3.2

The limb length can be assessed with or without the use of an image intensifier. The simple technique of using a cautery cable to measure the length of the femur from the ASIS to the upper pole of the patella, and measuring the length of the tibia from the tibial tubercle to the tip of the medial malleolus can be used. However, significant swelling in the thigh or knee may lead to measurement error. The length can also be assessed with the image intensifier using the meterstick technique (Fig 10-10).

Tibia

The tibial shaft is the straight part of the bone. Angulation can be detected clinically by palpation of the anterior tibial crest or the posteromedial crest. It is not difficult to reduce a multifragmentary tibial fracture, and align the plate in the center of the tibia in both the proximal and distal main fragments, which means the AP angulation is correct. The alignment is then confi rmed with a lateral x-ray. In the distal tibia, angulation can occur if the plate is not correctly precontoured.

3

Limb length discrepancy

Limb length discrepancy (LLD) occurs more often in the femur than the tibia. As the femur is covered by bulky muscles, its length is more difficult to evaluate than the tibia. The most common form of LLD is shortening, while distraction of the fracture is rarely seen. Multifragmentary fractures and long spiral fractures are sometimes difficult to evaluate for the correct length using the image intensifier. In such cases, the length may be measured clinically. Preoperative measurement of the length of the uninjured limb should be done as a reference. Alternatively, the contralateral uninjured limb is prepared and draped free during surgery so that it is available for comparison with the injured limb.

Fig 10-10

The limb length can be assessed with the image intensi-

fi er using the meterstick technique.

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Shortening may be caused by: Muscle contraction, especially if surgery is delayed. This shortening can be prevented by preoperative skeletal traction. Soft-tissue swelling and hematoma formation, which may produce a hydraulic effect that can resist the traction force. Sagittal plane angulation, which is frequently seen in simple fractures. After preliminary fi xation of the plate with one screw in each main fragment, the fracture is checked in an AP x-ray. The fracture may appear as if the bone ends are in contact with each other, thus giving the false impression that limb length is correct when in fact there is limb shortening due to AP angulation at the fracture site which will show up only on a lateral x-ray. Furthermore, correction of this AP angulation with restoration of correct limb length will be difficult as there is no space for manipulation unless the fracture is fi rst distracted to correct length before the AP angulation can be corrected. 3.1

Prevention of shortening

Check the length after fi xation by clinical or radiological means. Preoperative assessment of the length of the uninjured limb should be carried out for reference. Traction, which can be obtained in several ways. Manual traction is simple but maintaining the length during the fi xation procedure is difficult. A distractor or push–pull device (Chapter 3 Instruments) is helpful to maintain the length but needs more working space.

4

Neurovascular injuries

Neurovascular injuries, though uncommon, can result in significant morbidity. These complications are best prevented by understanding the anatomy, careful dissection, and gently protecting the neurovascular structures during surgery. 4.1

Humerus

Neurovascular injuries occur most commonly in MIPO of humeral fractures. During MIPO of humeral shaft fractures by the anterior approach, the radial nerve is at risk at three locations. In the proximal and distal incisions, the radial nerve is at risk if Hohmann retractors are used for muscle retraction. The radial nerve can be injured at the proximal incision by the tip of the medial Hohmann retractor. At the distal incision, the radial nerve can be injured by the lateral Hohmann retractor which may compress the nerve. In order to avoid this, Army Navy retractors should be used instead of Hohmann retractors (Fig 10-11). The radial nerve is also at risk as it runs along the posterior aspect of the middle third of the humerus during drilling or screw insertion in the anterior to posterior direction. Whenever possible, no screw should be inserted in this zone. If absolutely indicated screws should be inserted monocortically (Fig 10-12). The musculocutaneous nerve which lies between the biceps and the brachialis muscles needs to be identified and protected before preparing the tunnel for the plate. Another MIPO method to fi x humeral fractures consists of the use of a helical plate. This implant is introduced from the proximal humerus via a deltoid splitting approach and its helical configuration will then guide it with a twist to lie on the anterior aspect of the humeral shaft. There is a risk of injury to the axillary nerve with this approach (Chapter 11 Humerus, proximal: Fig 11-5). To avoid this, the deltoid muscle should not

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10

Complications and solutions

be split more than 5 cm distal to the acromion process, and the plate should be slipped close to the bone deep to the axillary nerve.

4.2

Femur

MIPO of the femur is safe and can be done on the lateral surface of the femur from the greater trochanter to the lateral femoral condyle. There is no structure at risk during MIPO of the femur. 4.3

Tibia

MIPO of the tibia on the medial side carries a risk of saphenous nerve injury at the proximal part and saphenous vein injury at the distal part (Fig 10-13). However, these complications do not result in any significant morbidity. MIPO on the lateral side of the tibia is safe in the proximal third and midshaft. In the distal third, the anterior tibial artery along with the deep peroneal nerve can be injured by the plate and the screws (Chapter 17 Tibia and fibula, shaft: 2.1 Structures at risk). These structures have to be identified before tunneling or plating. Fig 10-11

The radial nerve is vulnerable in the proximal and distal

incisions used for MIPO of the humeral shaft. To avoid injury to the radial nerve in these locations, retraction should be carried out with Army Navy retractors instead of Hohmann retractors.

Fig 10-12

Anteroposterior screw insertion in the midshaft of the

Fig 10-13

MIPO of the tibia on the medial side carries a risk of

humerus should be avoided if possible to prevent injury to the radial

saphenous nerve injury at the proximal part and saphenous vein

nerve at this level. If absolutely necessary, monocortical screws

injury at the distal part.

should be used.

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5

5.1

Early postoperative complication

Infection

The goal of the MIPO technique is to preserve the vascularity of the fractured bone and the surrounding tissue in order to promote fracture healing and reduce the rate of infection. The infection rate is low compared with conventional techniques. Even when MIPO is used for the defi nitive treatment of Gustilo type III open fractures or closed fractures with severe softtissue injuries, the infection rate remains low provided proper precautions are taken. Initial wound debridement followed by external fi xation should be carried out. Only when the softtissue condition is good enough and there is no sign of infection, the MIPO technique can be utilized as defi nitive treatment. The management of these difficult fractures requires much experience as well as careful preoperative planning from the fi rst step of external fi xation to the defi nitive fracture fi xation. For example, in cases of open fractures of the femur in which the plan is for defi nitive fi xation using the MIPO technique, after initial wound debridement, the fractures are reduced and the reduction maintained with an external fi xator. This should be placed on the anterior aspect of the femur so that when conditions are ready for MIPO to be carried out, the plate can be slipped along the lateral aspect of the femur without any interference from the external fi xator (Fig 10-14).

plating (eg, femur) is usually more difficult to diagnose, as the clinical symptoms of pain and fever may appear late. Laboratory fi ndings (raised erythrocyte sedimentation rate, C-reactive protein, and leukocyte count) often lead to the diagnosis. If there is any doubt about the presence of infection, early wound exploration is indicated. General principles of treatment of acute infection include early detection, drainage with debridement, antibiotics, and determination of implant stability. Infection after MIPO is usually not as bad as after conventional plating, as the infection is usually localized to the area of the plate. The soft tissue and periosteum outside the area of the plate are well preserved and the bone has a better chance to heal. The MIPO wound needs to be extended to allow drainage as well as adequate debridement of the necrotic bone and soft tissue around the area of the plate. The wound can be treated by open or closed wound treatment. The stability of the fi xation is assessed. The fi xation device can be left in place if it provides stability. Fracture healing can take place despite the presence of a low-grade infection. Implants are removed after solid bridging callus is seen. If the implant becomes loose, it must be removed and the fracture then stabilized with an external fi xator.

Infection following the MIPO technique is not common. However, when it occurs, early detection and treatment are essential. Subcutaneous and submuscular plating produce different clinical symptoms and signs when infection occurs. In the case of subcutaneous plating (eg, medial tibia), subcutaneous swelling, inflammation, and fever allow acute infection to be detected early. However, infection after submuscular 112

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10

Complications and solutions

Case: infection

a

b

c

d

Fig 10-14a–h a

A 36-year-old male involved in a motorcycle accident with a

c

Postoperative x-rays.

Gustilo type III open fracture of the left tibia. X-rays show the

d

10 days after surgery, the soft-tissue condition has improved. The fracture was then stabilized by the MIPO technique.

42-B wedge fracture. b

Debridement of the open fracture was done. The fracture was initially stabilized with an external fi xator.

e

Postoperative x-rays after MIPO using a 14-hole narrow DCP.

f

Purulent discharge was seen at the proximal

f

incision. g

Drainage and debridement was done and the wound was left open.

h

X-rays 5 months after surgery: The fracture has

e

g

h

healed with callus bridging the posterior cortex.

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6

6.1

Late postoperative complications

Implant failure

There are two types of implant failure: screw breakage and plate breakage. Most cases of implant failure following conventional plating techniques are due to plate breakage (Fig 10-15); screw breakage is rather uncommon. In contrast, with the MIPO technique, plate breakage is less common than screw breakage (Fig 10-16). The plate is fi xed to each main fragment by three to four screws which provide adequate stability for indirect bone healing to occur. Long plates, bridging a comminution with fi xation on either end of the bone, will undergo considerable deformation forces. As bending stress is distributed over a long segment of the plate, the stress per unit area is low, which reduces the risk of plate breakage. The three or four screws in each main fragment also absorb the load but the diameter of the screws is small, resulting in more frequent screw breakage from high stress. The healing of fractures treated with biological plating and indirect reduction technique is faster than with conventional plating, so implant failure is uncommon. However, if a large bone gap remains after MIPO, there is a higher risk of implant failure. In such cases, early cancellous bone grafting 6–12 weeks after surgery is advisable, especially if no callus formation is seen on the follow-up x-rays. In general, primary bone grafting is rarely needed in closed fractures treated with the MIPO technique. It is advisable only in cases of open fractures that have significant bone loss.

In multifragmentary fractures, it is preferable to use a longer plate that has a plate span ratio of more than 2–3 that of the fracture length (the quotient of the plate length and overall fracture length), while in simple fractures, the plate span ratio should be more than 8–10. Prevention of implant failure

Understand the concept of a bridging plate, MIPO technique, strain theory, and the biomechanics of plate and screw fi xation with this technique. Use as long a plate as possible and fi x both ends with adequate number of screws with at least three or four screws in each main fracture fragment. In severe soft-tissue injuries, open fractures, or fractures with large bone gaps, it is advisable to perform early bone grafting, usually 6 weeks after surgery if no sign of bridging callus is seen. 6.2

Delayed union

In the MIPO technique, it is generally accepted that the need for primary bone grafting for multifragmentary fractures is unnecessary. Biological plating or bridge plating is superior as regards bone healing than conventional plating. However, delayed union can occur even with the MIPO technique (Fig 10-17). The cause of delayed union may be the severity of the initial soft-tissue and bone injury (patient factor) which is uncontrollable. Another cause may be technical errors (surgeon factor) which can be avoided.

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10

Complications and solutions

Case: broken plate

a

b

c

Fig 10-15a–e a

A 30-year-old male met with a motorcycle accident. X-rays show a multifragmentary subtrochanteric fracture.

b

The fracture was stabilized with a 95° condylar plate. The lateral x-rays show a large fracture gap with gross displacement of the fracture fragments (white arrow).

c

The patient was lost to follow-up and came back only after 4 months with a broken plate and screw, and a nonunion at the area of the large gap. However, the distal part of the multifragmentary area

d

shows bridging callus.

e d

The x-rays show the fracture after revision of the plate and screws and autogenous bone grafting.

e

X-rays after 1 year show solid union of the fracture.

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Case: screw failure

Fig 10-16a–f a

b

c

d

a

A 35-year-old male with polytrauma, including head and chest injuries and a multifragmentary femoral shaft fracture.

b

The femoral fracture was stabilized with a broad DCP with improper application of the MIPO technique. The x-rays show the fracture fi xed with a 12-hole broad DCP with only two screws in each fragment.

c

2 weeks postoperatively, the screws failed.

d

X-rays after implant removal and revision using a 16-hole plate fi xed with three screws in each fragment.

e

f

e

X-rays 2 months postoperatively.

f

Fracture healing 6 months postoperatively.

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10

Complications and solutions

Case: delayed union

a

b

c

d

Fig 10-17a–e a

A 42-year-old male sustained a motorcycle accident with a multifragmentary subtrochanteric fracture.

b

The fracture was stabilized with a 95° condylar blade plate by the MIPO technique.

c

Postoperative x-rays show a large fracture gap and angulation.

d

Postoperative x-rays after 6 weeks show large fracture gap with small amount of callus formation.

e

e

X-rays 6 months after bone grafting show solid union of the fracture and two broken screws in the distal fi xation.

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Delayed union caused by technical errors by a surgeon may be: Malalignment of the fracture in the sagittal or frontal planes resulting in large residual bone defects that cannot heal by callus formation. Technical errors from the tunneling step. The correct positioning of the tunneler creates the tunnel over the periosteum and preserves the vascularity surrounding the fracture. An incorrect plane of dissection which strips the periosteum, as in the conventional technique, will destroy the bone vascularity and hence disturb the healing process. Repeated tunneling also damages the periosteal blood supply. The vascularity can be destroyed iatrogenically by excessive manipulation to achieve the unnecessary anatomical reduction of the multifragmentary zone, cerclage wiring, or lag screw fi xation. Markedly displaced fracture fragments or scattered bone pieces into the muscle may result in large gaps.

7

Suggested reading

Apivatthakakul T, Arpornchayanon O, Bavonratanavech S (2005) Minimally invasive plate osteosynthesis (MIPO) of the humeral shaft fracture. Is it possible? A cadaveric study and preliminary report. Injury; 36(4):530–538. Gautier E, Sommer C (2003) Guidelines for the clinical application of the LCP. Injury; 34(2):B63–B76. Kinast C, Bolhofner BR, Mast JW, et al (1989) Subtrochanteric fractures of the femur. Results of treatment with the 95 degree condylar blade-plate. Clin Orthop Relat Res; 238:122–130. Krettek C, Miclau T, Grun O, et al (1998) Intraoperative control of axes, rotation and length in femoral and tibial fractures Technical note. Injury; 29(3):C29–C39. Ochsner PE, Müller U (2000) Acute infection. Ruedi T, Murphy W, (eds) AO Principles of Fracture Management. Stuttgart New York: Georg Thieme Verlag, 733–751.

Prevention of delayed union

Employ indirect methods of fracture reduction. Avoid malalignment in the frontal and sagittal planes. Avoid large residual bone gaps at the fracture site. Prepare the submuscular tunnel for the plate in the correct plane over the periosteum. Avoid repeated tunneling. Avoid excessive direct manipulation of the fracture zone. If indirect reduction is unsuccessful, careful limited open reduction should be considered.

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Cases

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11

Humerus, proximal

1

Introduction

121

Cases

1.1

Classification

121

11.1

1.2

Indications and contraindications for MIPO

121

2

Surgical anatomy

122

3

Preoperative assessment

124

4

Preoperative planning

125

5

OR set-up

126

5.1

Anesthesia

126

5.2

Patient positioning and image intensifier

126

5.3

Implants and instruments

126

6

Operative procedure

127

6.1

Surgical approach

127

6.2

Fracture reduction

127

6.3

Plate insertion and fixation

128

7

Postoperative care

129

8

Pitfalls

129

9

Pearls

129

10

Suggested reading

130

Humerus, proximal: extraarticular unifocal fracture, nonimpacted, metaphyseal—11-A3

11.2

131

Humerus, proximal: extraarticular unifocal fracture, nonimpacted, metaphyseal—11-A3 with diaphyseal involvement

137

Teaching video on DVD-ROM 11

Humerus, proximal—anterolateral approach

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Authors

11

1

Merng Koon WONG, Suthorn BAVONRATANAVECH

Humerus, proximal

Introduction

Up to 80% of fractures of the proximal humerus can be treated conservatively. This is fortunate as the surgical management of these fractures can be difficult. The difficulties encountered include: Fracture reduction Exposure Fracture stabilization Increased risk of avascular necrosis Osteoporosis Prolonged rehabilitation with likelihood of pain and stiffness in the shoulder MIPO using indirect reduction and modern day implants such as locking compression plates (LCP) may help to address some of these concerns. However, not all proximal humeral fractures can be managed by these minimally invasive techniques, but when applicable, they can lead to improved outcomes. 1.1

Classification

a

1.2

c

Fig 11-1a–c a b c

11-A extraarticular unifocal fracture. 11-A1 tuberosity 11-A2 impacted metaphyseal 11-A3 nonimpacted metaphyseal

a

b

c

Fig 11-2a–c a

The Müller AO Classification is used for classification of proximal humeral fractures (Fig 11-1, Fig 11-2, Fig 11-3). The proximal humerus is designated by the number 11. Type A fractures are extraarticular unifocal, Type B are extraarticular bifocal and Type C fractures are articular fractures.

b

b c

11-B extraarticular bifocal fracture. 11-B1 with metaphyseal impaction 11-B2 without metaphyseal impaction 11-B3 with glenohumeral dislocation

Indications and contraindications for MIPO

One has to be selective when applying MIPO techniques for fractures of the proximal humerus.

a

b

c

Fig 11-3a–c

Displaced surgical neck fractures (11-A3), especially those with extensions into the shaft, surgical neck fractures with avulsion of the greater tuberosity (11-B1 and 11-B2), and

a b c

11-C articular fracture. 11-C1 with slight displacement 11-C2 impacted with marked displacement 11-C3 dislocated 121

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1

Introduction

(cont)

valgus impacted fractures (11-C1 and some 11-C2) are good indications because the connections to the rotator cuff and also the soft tissue and periosteal attachments between the fracture fragments usually remain intact in these fractures. This allows indirect fracture reduction using the principle of ligamentotaxis and at the same time ensuring the preservation of blood supply and biology.

2

Less suitable are those fractures with severe lateral displacement of the head fragment (some 11-C2) and severely displaced fracture dislocations (11-C3), unless they can—in younger patients—be satisfactorily reduced by closed methods and primary prosthetic replacement is not really suitable. Severe osteoporosis is a relative contraindication, as in these cases even angular stable implants may not provide the required stability to ensure fracture union.

Surgical anatomy

The axillary nerve runs along the deep surface of the deltoid muscle about 6 cm from the acromion and is at risk in a transdeltoid lateral approach used as an entry portal for the introduction of the plate in a craniocaudal direction. In order to avoid injury to the axillary nerve, the deltoid split should not extend for more than 5 cm beyond the lateral edge of the acromion. An additional precaution would be to place a “safetysuture” at this level to prevent propagation of the deltoid split. Further, during insertion of the implant through this approach, the plate should be kept close to the bone to avoid trapping the axillary nerve between the plate and the bone. The radial nerve lies close to the lateral aspect of the distal humerus. A long plate applied laterally would risk injuring the radial nerve at the distal part of the humeral shaft where it pierces the lateral intermuscular septum distal to the deltoid insertion. Also, the nerve is at risk of compression by the tip of a Hohmann retractor applied to the lateral aspect of the humeral shaft to expose the distal humerus when a long plate is applied for osteosynthesis. Because of this, it is safer to use Army Navy retractors for this purpose rather than Hohmann retractors.

The tendon of the long head of the biceps lies in the groove between the greater and lesser tuberosities of the humerus and serves as an important landmark. It may also be trapped between the bony fragments in displaced proximal humeral fractures and prevent closed fracture reduction. Running alongside the tendon of the long head of the biceps in the intertubercular groove is the lateral ascending branch of the anterior humeral circumflex artery carrying the main blood supply to the upper part of the humeral head. Damage to this artery can lead to avascular necrosis of that part of the humeral head (Fig 11-4). Fractures of the anatomical neck of the humerus should be distinguished from surgical neck fractures. In anatomical neck fractures the blood supply to the main head fragment is frequently disrupted, thus increasing the likelihood of avascular necrosis. In contrast, surgical neck fractures do not carry this risk as the blood supply usually remains intact.

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11

2

Humerus, proximal

Surgical anatomy

(cont)

The deltoid insertion into the lateral aspect of the proximal shaft of the humerus forms an obstacle to the passage of a long plate applied laterally. To pass the deltoid insertion, twisting of the plate 90º into a helical shape allows it to pass from the lateral aspect of the proximal humerus (subdeltoid space) onto the anterior aspect of the distal half of the humerus (subbrachialis space) (Fig 11-5).

Displaced fractures of the proximal humerus are difficult to reduce, because of the deforming forces exerted by the muscle attachments to the humeral tuberosities and shaft (Fig 11-6).

a Fig 11-4 The anterior circumflex artery with its branches. The greater and lesser tuberosities, with their respective rotator cuff insertions counteract each other in rotary function.

b

Fig 11-5a–b

A helical plate avoids both the deltoid insertion and radial nerve in the distal arm by its anterior twist.

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2

Surgical anatomy

(cont)

Supraspinatus

Subscapularis

Pectoralis major

a

b

Fig 11-6a–b Fractures of proximal humerus with displacement are difficult to reduce because of the deforming forces exerted by muscle attachments.

3

Preoperative assessment

Preoperative assessment includes a carefully performed clinical and radiological examination. Clinically, it is important to assess the neurovascular status of the upper limb with special attention paid to the integrity of the brachial plexus and axillary nerve. Also to be noted is the degree of swelling in the shoulder, whether the shoulder is dislocated and any other associated injury that may be present.

Radiological assessment should include the “trauma-series” x-rays of AP, axillary and lateral transscapular views. A CT scan in combination with 3-D reconstruction is very useful in providing additional information on the extent of articular injury and fragment displacement.

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11

4

Humerus, proximal

Preoperative planning

Once a decision has been made that the case is suitable for MIPO, a good preoperative plan helps facilitate the subsequent execution of the surgical procedure. The plan should include a

graphic representation of the fracture fragments, the reduction technique, the surgical approach, the most appropriate implant, and the steps required in its application (Fig 11-7).

a

d

b

c

e

Fig 11-7a–e a b c d e

Preoperative planning for a proximal humeral fracture with extension to the shaft. The metaphyseal plate is contoured according to the shape of the humeral head. A locking proximal humerus plate (LPHP) can be used as a template. The plate is placed lateral to the biceps tendon. The upper level of the plate has to lie about 1 cm below the greater tuberosity. Trapping of the axillary nerve has to be avoided. A cortex screw may be applied fi rst to fi x the proximal segment of the plate to the humeral head fragment before the addition of two LHS. The radial nerve must not lie under the plate. Manual traction aligns the fracture fragments. This should be done with the arm by the side of the chest in neutral rotation. Screw fi xation of the distal fragment; either cortex screws or LHS may be used, depending on their intended function and the bone quality.

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5

OR set-up

5.1

Anesthesia

A trial manipulation may be carried out to test the feasibility of closed reduction.

General or regional anesthesia may be used, depending on the patient’s condition. Even with general anesthesia, a supplementary brachial block may be administered for postoperative pain control. 5.2

The arm is draped to allow free mobility of the shoulder and elbow. Flexion of the elbow to 90˚ with the arm in neutral or slight internal rotation may help to restore axial realignment of the fracture.

Patient positioning and image intensifier 5.3

A beach-chair position with the patient’s head supported on a head rest is preferred. A supine position on a radiolucent operating table with a pad under the scapula is also possible, though not optimal (Fig 11-8). The image intensifier is brought in from the cranial direction and the C-arm positioned to take AP and axillary views of the shoulder. Pilot screening before sterile draping should be carried out to check that satisfactory images can be obtained.

An LCP is the preferred implant for fi xation of proximal humeral fractures, especially in the presence of osteoporosis, which is not uncommon in patients with these injuries. Although not foolproof, locking plates have at least reduced the rate of implant loosening and failure that are not infrequently encountered when conventional plates are used. The locking proximal humerus plate (LPHP) and the PHILOS are specifically designed for the proximal humerus.

c

b

a

Implants and instruments

Fig 11-8a–c a b

Beach-chair position and position of image intensifier. The arm is draped to allow free movements of the shoulder and elbow.

c

AP and lateral views of the proximal humerus taken with the image intensifier.

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11

5

Humerus, proximal

OR set-up

(cont)

These facilitate minimally invasive indirect reduction and fi xation of these fractures. Some contouring may be necessary however, especially when a long plate is used for fractures with distal extensions down the humeral shaft.

6

Operative procedure

The main steps in the application of the LPHP using the MIPO technique are outlined below. 6.1

Another implant that is sometimes used is the LCP L-plate. With this plate, it is easier to avoid the deltoid insertion, but the plate must be of adequate length.

Surgical approach

A transdeltoid lateral approach is used for the proximal introduction of the plate, care being taken not to split the deltoid fibers beyond 5 cm distal to the lateral edge of the acromion in order to avoid injuring the axillary nerve (Fig 11-9).

6.2

Fracture reduction

Reduction of the humeral head fractures is then performed. This is necessary as the locking head screws (LHS) used in the proximal segment of the LPHP cannot exert compression and so are not suitable for indirect reduction. Reduction is performed under fluoroscopic guidance by manipulation and with the help of elevators, bone hooks, and 3 mm Steinmann pins as joysticks. Valgus impacted fractures should be disimpacted and the head fragment reduced to its anatomical position. Once satisfactory reduction has been obtained, the reduction is temporarily held with K-wires. The K-wires should not be placed in positions that may jeopardize the axillary nerve or interfere with the subsequent placement of the LPHP (Fig | Anim 11-10).

Fig 11-9

Anterolateral incisions for MIPO technique.

If the greater or lesser tuberosities are avulsed, these should be reduced and fi xed. The recommended way to fi x these fractures is by the use of nonabsorbable sutures, as the holding power of sutures is stronger than that of screws, especially in osteoporotic bone. Furthermore, sutures will not interfere with the subsequent placement of LHS in the proximal segment of the LPHP. The sutures are placed close to the bony insertions of the subscapularis, supraspinatus, infraspinatus, or teres minor tendons—depending on which tuberosity is avulsed—and then passed through the appropriate suture 127

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6

Operative procedure

(cont)

plate is used, it should fi rst be precontoured into a helical shape to allow it to fit onto the lateral surface of the humerus proximally and its anterior surface distally.

Animation

The proximal segment of the plate should be centered over the greater tuberosity at least 5 mm distal to its proximal edge and 10 mm lateral to the posterior lip of the intertubercular groove.

Fig | Anim 11-10

Fracture reduction with joystick and temporary fi xation with K-wires.

holes in the proximal segment of the LPHP. The sutures are tightly knotted only after defi nitive fi xation of the LPHP. Even if the tuberosities are not fractured, it is prudent to apply these anchoring sutures as the stability and holding power of the LPHP are improved by the application of these sutures since they tend to counteract the muscle tension. 6.3

Plate insertion and fixation

The next step is to create a tunnel for the plate using a tunneling instrument. In cases where the fracture extends distally down the shaft, a long implant has to be used, and the submuscular tunnel must be created from the lateral subdeltoid space to the anterior subbrachialis space. Some resistance may be encountered at the transition between these two spaces due to the mixture of strong fibres from the anterior deltoid and lateral brachialis; so some force may be required. The tunneling instrument is then replaced by the LPHP with the guiding block mounted on its proximal segment. If a long

The proximal segment of the LPHP is then temporarily fi xed to the humeral head fragment with one or two K-wires introduced through threaded LCP drill guides mounted through the guiding block. The position of these K-wires is checked with the image intensifier. If necessary at this point, the shaft fragment is reduced onto the head fragment and plate under fluoroscopic guidance. A short incision is then made over the distal end of the plate using Henry’s approach by splitting the brachialis at its center. Having ensured that the plate is centered over the anterior cortex of the distal humeral shaft, it is temporarily fi xed to the bone with a K-wire introduced through a threaded drill guide. The position of the LPHP and the quality of fracture reduction achieved is checked with the image intensifier. If satisfactory, the proximal K-wires are replaced by LHS after predrilling, removal of the threaded LCP drill guide, and length measurement. At least four screws should be inserted proximally into the head fragment. Distal fi xation is then carried out. Standard cortex screws can be applied through the dynamic compression part of the combination hole in the distal segment of the LPHP for indirect reduction or to generate interfragmentary compression. If used, cortex screws should be applied before the LHS. At least three screws should be used bicortically to fi x the distal segment of the plate to the humerus.

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11

7

Humerus, proximal

Postoperative care

Postoperatively, an arm sling is applied. If the quality and stability of the fi xation achieved is satisfactory, early passive motion is started from the fi rst postoperative day. This 8

Pitfalls –

progresses to protected active and active assisted exercises as fracture union occurs.

9

Pearls +

Pitfall 1

Pearl 1

The axillary nerve is vulnerable at several stages of the operation: During the transdeltoid lateral approach, the deltoid split should not extend more than 5 cm distal to the lateral edge of the acromion. During plate insertion, the plate should be kept close to the humerus to avoid trapping the axillary nerve between the plate and the bone. During insertion of K-wires to temporarily fi x the reduced humeral head fragment, the K-wires should, if possible, avoid the zone 6 cm distal to the acromion and should be placed at a slightly anterolateral angle with the arm in internal rotation.

The LPHP should be correctly positioned. Placing the plate too high may cause subacromial impingement. Placing it too low may limit the number of LHS that can be inserted into the humeral head fragment. Placing it too anteriorly may damage the lateral ascending branch of the anterior circumflex humeral artery, which is the main blood supply to the proximal part of the humeral head.

Pitfall 2

Pearl 2

The radial nerve is vulnerable in several parts along its course if a long plate is used: As it runs along the spiral groove posterior to the midshaft of the humerus, it may be injured by the drill bit or tips of screws placed in an anteroposterior direction. It is therefore best not to insert screws through the plate in an anteroposterior direction in the middle third of the humerus. As it pierces the lateral intermuscular septum, a long plate applied on to the lateral aspect of the humerus may trap the radial nerve here. Along the lateral aspect of the distal humerus, the tip of a Hohmann retractor applied here to expose the distal end of the plate may compress the radial nerve against the lateral humeral cortex.

Twisting the plate into a helical shape during contouring may damage the threads of the locking screw holes. This can be prevented by inserting spacers or threaded drill sleeves into the threaded portions of the combination holes at the zone of plate deformation.

Pearl 3

In osteoporotic bone, the LHS placed into the humeral head fragment should not be too long so that the tips are not too close to the articular surface as there is a risk of screw tip penetration due to settling at the fracture site.

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10

Suggested reading

Fernandez Dell’Oca AA (2002) The principle of helical implants. Unusual ideas worth considering. Case studies. Injury; 33 Suppl 1:SA29–40. Resch H, Hubner C, Schwaiger R (2001) Minimally invasive reduction and osteosynthesis of articular fractures of the humeral head. Injury; 32 Suppl 1:25–32. Rüedi TP, Murphy WM (2001) AO Principles of Fracture Management. Stuttgart New York: Georg Thieme Verlag.

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Authors

11.1 1

Merng Koon WONG, Suthorn BAVONRATANAVECH

Humerus, proximal: extraarticular unifocal fracture, nonimpacted metaphyseal—11-A3 Case description

A 58-year-old male motorcyclist with past history of gouty arthrititis was involved in a road traffic accident. He sustained multiple injuries requiring intensive care for 2 days, followed by respiratory treatment for 1 week due to severe bilateral hemopneumothorax. The initial orthopedic management was conservative, by immobilization, because of chest injury. Operative treatment is indicated due to fracture displacement and to allow early mobilization of the shoulder.

Fig 11.1-1a–d a–b c a

c

b

d

Multifragmentary fracture in the metaphyseal region of the proximal right humerus. Bilateral hemopneumothorax, bilateral chest-tube drainage, resorbing subcutaneous emphysema. Markedly displaced distal left clavicular fracture.

d

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11

2

Humerus, proximal

Indication for MIPO

3

In 11-A3 fracture with metaphyseal comminution, MIPO is ideal to preserve blood supply in fracture zone. In addition, it was possible

Patient positioning

The patient is placed in the beach-chair position to optimize reduction and fi xation.

to reduce the head fragment to the humeral shaft by gentle manipulation.

4

Surgical approach

a

b

Fig 11.1-2a–d a

c

d

Longitudinal incision from anterolateral tip of acromion. b Incision is limited to 5 cm to avoid injuring the axillary nerve. c Deltoid muscle is split using blunt dissection. d Subacromial dissection to free the rotator cuff for mobilization. In 11-A2, 11-B2, and 11-C2 fractures, supraspinatus and subscapularis tendons are dissected and marked by strong sutures for fi nal anchorage to an LPHP. Rotator cuff anchorage is to correct anteversion or retroversion and to reduce displaced tuberosities.

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11.1

5

Humerus, proximal: extraarticular unifocal fracture, nonimpacted metaphyseal—11-A3

Reduction Fig 11.1-3a–f a

Direct reduction using joysticks and traction preserves blood supply at fracture site. Once reduction is achieved, K-wires are driven axially to medial distal shaft area. b LPHP is contoured into a helical shape to avoid deltoid insertion. c Plate is slipped into a submuscular, extraperiosteal tunnel, along the shaft using helical contouring to avoid deltoid insertion. d LPHP can be fi xed preliminarily by a K-wire through a threaded drill guide to allow adjustment. e Dissection through a small incision to localize plate end distally. f Note visualization of plate centered on anterior aspect of humeral shaft.

a

c

d

e

f

b

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11

6

Humerus, proximal

Fixation

a

b

Fig 11.1-4a–f a–b c–d

c

e

e–f

d

LPHP fi xation proximally and distally. Image intensifier is used to check screw length especially in humeral head, the reduction of fracture, and location of distal plate end. Locking head screws (LHS) must not be placed eccentrically. Plate insertion using small proximal and distal incisions.

f

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11.1

6

Humerus, proximal: extraarticular unifocal fracture, nonimpacted metaphyseal—11-A3

Fixation

(cont)

Fig 11.1-5

a

b

Deltoid split is repaired with absorbable suture material.

Fig 11.1-6a–b

Postoperative x-rays. Note: the distal screw could not be inserted as it would not have engaged the bone.

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11

7

Humerus, proximal

Rehabilitation

Following the fi rst month of physiotherapy, patient had to be transferred to internal medicine due to gouty arthritis. Range of motion 3 months postoperatively: abduction and flexion 90°, extension 20°, external rotation 30° and full internal rotation. Patient underwent shoulder manipulation under anesthesia, leading to 140° abduction and flexion, 40º extension and 60° external rotation.

a

a Fig 11.1-7a–b

b

Postoperative x-rays after 12 weeks, fracture healed in proper alignment.

b

c Fig 11.1-8a–c Range of motion 6 months postoperatively, compared to the uninjured shoulder, show good results.

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Author

11.2 1

Frankie KL LEUNG

Humerus, proximal: extraarticular unifocal fracture, nonimpacted metaphyseal—11-A3 with diaphyseal involvement

Case description

A 44-year-old male injured his left upper arm in a motor vehicle accident and sustained a closed fracture of proximal humerus with extension to the diaphysis.

F ig 11. 2-1a – c

a

2

b

Preoperative x-rays show a multifragmentary fracture of proximal humerus involving greater tuberosity and surgical neck, and extending to humeral shaft with a medial wedge fragment. A cast was applied initially.

c

Indication for MIPO

Operative treatment was indicated in this case as the fracture was

in screw placement but use of locking head screws (LHS) will greatly

unstable making conservative treatment difficult and prolonged

improve stability.

with a strong likelihood of residual shoulder stiffness. Use of an intramedullary nail was contraindicated since comminution in proximal metaphysis prevents successful proximal locking. Conventional compression plating was not suitable either as it involves extensive surgical dissection. Insertion of a locking com-

3

Patient positioning

pression plate (LCP) as a bridging internal fi xator is the treatment of choice. The small proximal humeral fragment poses great diffi culty

The patient is placed in a beach-chair position.

137

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11

4

Humerus, proximal

Surgical approach

a

c

d

Fig 11.2-2a–d a b

Small anterolateral incision is made 1 cm below acromion. Deltoid muscle is split, exposing greater tuberosity. b–d The thinned proximal part of the metaphyseal plate facilitates contouring. To avoid the radial nerve which lies along the lateral aspect of the distal third of the humerus, it may be necessary to twist the plate into a helical shape so that its distal part lies over the anterolateral aspect of the humeral shaft.

Fig 11.2-3

Plate is inserted through the proximal incision. To avoid the deltoid insertion, a more anterior tunnel is made. Care must be taken to keep the plate close to the bone; otherwise the axillary nerve proximally or the radial nerve distally may be trapped between the plate and the bone. (Alternatively, after making the proximal incision and before plate insertion, the distal incision can be made along the anterolateral aspect of the arm; the biceps retracted medially and the brachialis splits along its midline to expose the anterior surface of the distal humeral shaft; submuscular tunneling from both incisions can then be done using the plate itself or with the aid of a tunneler.)

138

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11.2

4

Humerus, proximal: extraarticular unifocal fracture, nonimpacted metaphyseal—11-A3 with diaphyseal involvement

Surgical approach

(cont)

Fig 11.2-4

A 5 cm distal incision is made after confi rmation of correct plate placement by use of an image intensifier.

5

Reduction

Fig 11.2-5 LCP drill sleeves are fi xed to plate and fi ne adjustment is performed to optimize plate position.

a

b

Fig 11.2-6a–b

Fracture is reduced by traction and manipulation to ensure correct length and alignment. K-wires are inserted for temporary fracture fi xation using drill sleeves. 139

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11

6

Humerus, proximal

Fixation

a

b

Fig 11.2-7a–b

Proximal fi xation is performed using four 3.5 mm LHS, distal fi xation using three 5 mm LHS.

7

Fig 11.2-8

Postoperative x-ray. A precise reduction of diaphyseal fragments has not been achieved.

Rehabilitation

Assisted active shoulder physiotherapy starts on fi rst postoperative day. Load bearing allowed after 4 weeks.

Fig 11.2-9

Surgical wound healing.

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11.2

7

Humerus, proximal: extraarticular unifocal fracture, nonimpacted metaphyseal—11-A3 with diaphyseal involvement

Rehabilitation

a

(cont)

b

Fig 11.2-10a–b

Follow-up after 3 months, satisfactory callus formation, no loosening of fi xation.

a Fig 11.2-11

3 months after surgery: minimal pain with satisfactory range of motion.

b

Fig 11.2-12a–b

Excellent range of motion 18 months after surgery—implants had been removed.

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11

7

Humerus, proximal

Pitfalls –

8

Pearls +

Pitfall 1

Pearl 1

Axillary nerve may be injured in the proximal deltoid splitting incision.

An anterolateral incision is used to avoid damage to axillary nerve.

Pitfall 2

Pearl 2

Radial nerve can be damaged during distal dissection.

Using the distal part of Henry’s approach, that is retracting the biceps medially and splitting the brachialis along its midline to expose the anterior cortex of the humeral shaft, can avoid injury to the radial nerve. Army Navy retractors should be used for retracting the two halves of the brachialis instead of Hohmann retractors.

Pitfall 3

Pearl 3

Deltoid insertion in proximal humerus hinders plate positioning.

To avoid damaging the deltoid insertion, a more anterior tunnel is preferred. Torsional contouring of implant into a helical shape is useful for plate positioning on lateral aspect of proximal humerus and on anterior aspect of distal humerus.

142

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143

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12

Humerus, shaft

1

Introduction

145

Cases

1.1

Classification

146

12.1

1.2

Indications and contraindications for MIPO

146

2

Surgical anatomy

146

2.1

Bone

146

2.2

Muscles

146

2.3

Nerves

147

2.4

The safe zone of the humerus

147

3

Preoperative assessment

149

4

Preoperative planning

149

5

OR set-up

150

5.1

Anesthesia

150

5.2

Patient positioning and image intensifier

150

5.3

Implants and instruments

150

6

Operative procedure

151

6.1

Surgical approach

151

6.2

Preparation and passage of the tunneling

Humerus, shaft: wedge fracture, bending wedge—12-B2

12.2

157

Humerus, shaft: complex fracture, irregular—12-C3

163

12.3

Humerus, shaft: complex fracture, spiral—12-C1 169

12.4

Humerus, shaft: wedge fracture, fragmented wedge—12-B3

173

Teaching video on DVD-ROM

instrument

152

6.3

Passage of the implant

152

6.4

Reduction and fixation

153

7

Postoperative care

154

8

Pitfalls

154

9

Pearls

154

10

Suggested reading

156

12

Humerus, shaft—anterior approach

144

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Author

12

1

Theerachai APIVATTHAKAKUL

Humerus, shaft

Introduction

Fractures of the shaft of the humerus account for 1% of all fractures. Most of these fractures can be treated conservatively by functional bracing with satisfactory outcomes. The humerus is not a weight-bearing bone and shortening is better tolerated while malalignment can be compensated by the shoulder and elbow joints. If the alignment is not acceptable, operative treatment with internal fi xation should be considered. There are several methods of fi xation available, namely, plate fi xation, intramedullary nailing, and external fi xation. The choice of method is based on the condition of the soft tissues, fracture location and configuration, bone quality, canal diameter, facilities and resources available, and the skills and experience of the surgical team. While external fi xation is reserved mainly for open fractures or closed injuries with severe softtissue compromise, plating and intramedullary nailing can both be used for most humeral shaft fractures. Locked intramedullary nailing can be done through relatively small incisions and so incurs less soft-tissue trauma. Plate fi xation, on the other hand, is technically demanding, requiring extensive exposure and soft-tissue dissection, but it can provide stable fi xation. In order to make use of the advantages of plate fi xation while avoiding the disadvantages of open plating such as excessive soft-tissue stripping and devascularization, the plate may be introduced using MIPO techniques. The problem with MIPO for humeral shaft fractures is the presence of the major nerves and the brachial vessels which, if injured, can lead to serious consequences. Anatomical studies have shown that there is a “safe zone” in the humerus that is not crossed by any major nerve or vessel and thus is suitable for MIPO techniques. This safe zone is the anterior surface of the humeral shaft deep to the brachialis muscle.

a

b

c

Fig 12-1a–c

12-A simple fracture. 12-A1 spiral b 12-A2 oblique (≥ 30º) c 12-A3 transverse (< 30º) a

a

b

c

Fig 12-2a–c

12-B wedge fracture. 12-B1 spiral wedge b 12-B2 bending wedge c 12-B3 fragmented wedge a

a

b

c

Fig 12-3a–c

12-C complex fracture. a 12-C1 spiral b 12-C2 segmental c 12-C3 irregular

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1

Introduction

1.1

Classification

(cont)

In the Müller AO Classification, the shaft of the humerus is identified by the number 12. The A, B, C classification distinguishes between simple (A), wedge (B), and complex (C) fractures (Fig 12-1, Fig 12-2, Fig 12-3). 1.2

Indications and contraindications for MIPO

MIPO can be performed for most closed humeral shaft fractures. The plate is usually applied according to the principle of bridge plating and the radial nerve is not usually identified.

An absolute contraindication for MIPO in humeral shaft fractures is the presence of radial nerve palsy, since the radial nerve is not exposed or identified during the MIPO procedure. MIPO should also not be used in the following situations: Severe tissue loss without coverage of exposed bone Osteomyelitis Delayed surgery with shortening Delayed reconstructions (eg, requiring bone grafting)

Good indications for MIPO are: Comminuted fractures Fractures extending to the proximal or distal shaft Segmental fractures Small medullary canals (< 8 mm) Deformed shaft (malunions) Open growth plates

2 2.1

Surgical anatomy Bone

The humeral shaft extends from the inferior border of the pectoralis major insertion proximally to the supracondylar ridge distally. This region encompasses the middle 3/5 of the entire humerus. Cross-sectional shape varies from round proximally to triangular distally (Fig 12-4). The anterior aspect of the humerus possesses an anterior ridge with anterolateral and anteromedial surfaces. The posterior aspect of the humerus presents a broad, flat surface extending from the posterior aspect of the neck of the humerus to the olecranon fossa distally. The deltoid tubercle forms a lateral prominence just

proximal to the midshaft. Knowledge of the bony anatomy of the humerus is essential when contouring the plate to fit the bony surface. 2.2

Muscles

The arm has two major muscle compartments, flexor and extensor, which are separated by the medial and lateral intermuscular septi. The flexor or anterior compartment contains three muscles: the coracobrachialis, the biceps brachii, and the brachialis. All are supplied by the musculocutaneous nerve except the lateral part of the brachialis which is supplied by

146

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12

2

Humerus, shaft

Surgical anatomy

(cont)

the radial nerve. The extensor, or posterior, compartment has only one muscle, the triceps brachii, which is supplied by the radial nerve. 2.3

Nerves

The radial nerve is a continuation of the posterior cord of the brachial plexus. It runs along the posterior wall of the axilla, and then passes through the triangular space formed by the long head of the triceps, shaft of the humerus, and the teres major muscle. The nerve crosses from medial to lateral by lying in the spiral groove close to the bone on the posterior aspect of the midshaft of the humerus. After crossing the posterior surface of the humerus, the radial nerve pierces the lateral intermuscular septum to enter the anterior compartment where it lies between the brachialis and brachioradialis. In this area the radial nerve is separated from the bone by the brachialis muscle. The median nerve lies in the anterior compartment and runs alongside the brachial artery on the anteromedial aspect of the arm. In the upper arm, the ulnar nerve lies posterior to the brachial artery in the anterior compartment. After running down 2/3 of the arm, it pierces the medial intermuscular septum to enter the posterior compartment and then continues distally to the posterior aspect of the medial epicondyle. The musculocutaneous nerve is a branch of the lateral cord. The nerve enters the coracobrachialis about 5–8 cm distal to the coracoid process on its medial side. After piercing the coracobrachialis, it runs on the anterior surface of the brachialis and branches to supply the biceps and medial part of the brachialis muscle. The nerve continues distally to supply sensation to the lateral forearm (lateral cutaneous nerve of the forearm).

2.4

The safe zone of the humerus

To identify the safe zone of the humerus, it is necessary to understand the cross-sectional anatomy of the proximal, middle, and distal humerus (Fig 12-4). In the proximal humerus, the axillary vessels and three nerves (radial nerve, median nerve, and ulnar nerve) run along its medial side. The branches of the axillary nerve and posterior humeral circumflex vessels are posterior and continue laterally. The only safe zone that has no neurovascular structures in the proximal humeral shaft is its anterior aspect (Fig 12-4a). The profunda brachii vessels and the radial nerve run close to the posterior aspect of the midshaft of the humerus in the spiral groove. The brachial artery and vein along with the median and ulnar nerves are on the medial side of the humerus. The musculocutaneous nerve lies on the anterior surface of the brachialis muscle. The safe zone of the midshaft of the humerus is its anterior surface deep to the brachialis muscle (Fig 12-4b). In the distal arm, the radial nerve moves laterally and, after piercing the lateral intermuscular septum, lies between the brachialis and the brachioradialis muscles lateral to the humerus. The brachial vessels, median nerve and ulnar nerve are on its medial side. The musculocutaneous nerve lies anterior to the brachialis muscle. The safe zones of the distal shaft of the humerus include its posterior surface as well as its anterior surface deep to the brachialis muscle (Fig 12-4c). From these three cross-sectional studies, it is evident that the safe zone for the percutaneous insertion of a straight plate for the humeral shaft is on its anterior surface deep to the brachialis muscle (Fig 12-5).

147

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2

Surgical anatomy

(cont)

1

Musculocutaneous nerve

2

Radial nerve

1 2

a

1 2

b

1 2 c

Fig 12-4a–c

Cross-sectional anatomy of humeral shaft.

Fig 12-5 Approaches to the anterior aspects of the proximal and distal humeral shaft.

148

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12

3

Humerus, shaft

Preoperative assessment

A complete neurovascular assessment is necessary. The vascular status of the extremity should be evaluated by palpation of the distal pulses and assessment of the capillary refi ll. All peripheral nerves should be assessed, especially the radial nerve which has a high risk of injury due to its close proximity to the humerus.

4

Radiographic evaluation must include anteroposterior and lateral projections of the entire humerus, as well as views of the shoulder and elbow joints. This approach confi rms the diagnosis of the fracture and prevents missing associated injuries in the adjacent joints.

Preoperative planning

MIPO of the humerus is technically more demanding than conventional plating. Indirect reduction, tunneling, and percutaneous fi xation techniques require accurate preoperative planning to choose the appropriate type of implant, its length,

a Fig 12-6a–e

b

c

the number and position of the screws, and their order of insertion. Preoperative planning by x-ray overlaying and stepby-step planning of the surgical procedure is necessary (Fig 12-6).

d

e

Example of a preoperative plan, with step-by-step execution of the procedure. 149

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5

OR set-up

5.1

Anesthesia

Surgery is usually performed under general anesthesia. 5.2

Patient positioning and image intensifier

The patient lies in a supine position with the arm abducted 90° and the forearm in full supination. The arm is rested on a radiolucent side-table (Fig 12-7). An image intensifier is essential and is positioned on the same side of the operating table as the arm to be operated on. 5.3

Implants and instruments

Implants for MIPO of the humerus

The narrow dynamic compression plate (DCP) 4.5 can be used for MIPO of humeral shaft fractures. The plate is minimally precontoured at the proximal part in order to fit the anterior ridge. The plate should be long enough to bridge the fracture segment while permitting at least three to four screws each in the main proximal and distal fracture fragments. The locking compression plate (LCP) with locking head screws (LHS) functions as an internal fi xator. There is little or no contact with the bone surface and so minimal additional damage to the blood supply is caused. Exact precontouring to fit the bone surface is not required. At least three screws in each fragment are required to achieve stable fi xation.

Plate length

The length of the plate remains a controversial issue. With the MIPO technique, plate length can be increased with minimal additional soft-tissue dissection. The plate can be divided into three segments: a proximal segment, a middle segment over the fracture site between the two innermost screws, and a distal segment. The proximal and distal segments of the plate should allow at least three to four screws to be applied on each main fracture fragment; the most proximal screw should be about 3 cm distal to the bicipital groove and the most distal screw about 1–2 cm proximal to the olecranon fossa. Number of screws and order of screw placement

From the biomechanical point of view, for fractures of the humerus, three or four screws on either side of the fracture should be used, as rotational forces predominate in the humerus. In simple fractures with a small fracture gap, at least one or two plate holes on each side of the fracture should be left without screws in order to allow some degree of micromotion that will act as a stimulus for callus formation. In multifragmentary fractures, the two innermost screws should be applied as close as possible to the fracture site while the remaining screws should be spread over each of the proximal and distal main fracture fragments.

Fig 12-7

The patient in supine position with the arm abducted 90° and the forearm in full supination.

150

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12

6 6.1

Humerus, shaft

Operative procedure Surgical approach

brachialis is identified. The biceps is retracted medially to expose the musculocutaneous nerve lying on the anterior surface of the brachialis (Fig 12-8c). The brachialis is then split longitudinally along its midline to reach the periosteum of the anterior cortex of the distal humerus (Fig 12-8d). The musculocutaneous nerve is retracted together with the medial half of the split brachialis, while the lateral half serves as a cushion to protect the radial nerve, which at this point, has pierced the lateral intermuscular septum and is lying between the brachioradialis and brachialis muscles.

The interval between the lateral border of the proximal part of the biceps and the medial border of the deltoid is palpated. A 3 cm proximal incision is made approximately 6 cm distal to the anterior part of the acromion process and the dissection is carried down to the humerus (Fig 12-8a). Distally, a 3 cm incision is made along the lateral border of the biceps approximately 5 cm proximal to the flexion crease of the elbow (Fig 12-8b). The interval between the biceps brachii and the

a

b

Fig 12-8a–d

c

d

Step-by-step approaches to the proximal and distal humeral shaft.

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6 6.2

Operative procedure

(cont)

Preparation and passage of the tunneling instrument

A subbrachialis, extraperiosteal tunnel is created by passing a tunneling instrument deep to the brachialis from the distal to the proximal incision (Fig 12-9a). Some difficulty may be encountered during passage of the tunneling instrument at the proximal part of the tunnel due to the intimate blending of the fibres of the brachialis and deltoid muscles along the lateral aspect of the tunnel at this point. Incision of these muscle fibres at the tip of the tunneling instrument will allow

a Fig 12-9a–c

b

its passage through to the proximal incision. To avoid injury to the radial nerve at the lateral aspect of the distal humerus, the tunneling instrument should be passed along the anterior, or slightly anteromedial aspect of the humerus. 6.3

Passage of the implant

After preparation of the anterior subbrachialis tunnel, the selected narrow DCP or LCP is tied with a suture to a hole at the tip of the tunneling instrument. The tunneling instrument is then withdrawn, pulling with it the plate along the track

c

Plate insertion in MIPO technique.

152

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12

6

Humerus, shaft

Operative procedure

(cont)

that it has created (Fig 12-9b–c). This method ensures that the plate is guided into the correct tunnel and avoids injury to the radial nerve. 6.4

Reduction and fixation

The plate is then fi xed to the proximal humerus with one screw (Fig 12-10a). Reduction of the fracture is usually achieved by manipulation. Traction is used to restore the length and rotation. After positioning the plate over the center of the

a

anterior surface of the distal humerus, one screw is inserted distally (Fig 12-10b). Varus and valgus angulation is checked with the image intensifier. When the alignment is correct, one more screw is inserted into each fragment. The alignment is reassessed with the image intensifier and, if satisfactory, the fi xation is completed with at least three screws in each fragment (Fig 12-11). When using a DCP or an LC-DCP, it is preferable to fi x the screws in a divergent direction to catch more area of the cortex. The divergent screw direction also requires smaller and fewer incisions.

b Fig 12-11

Fig 12-10a–b

Temporary plate fi xation, proximally and distally.

After correct alignment, fi xation is completed with at least three screws in each fragment.

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7

Postoperative care

After removal of the suction drain, the patient is encouraged to perform passive exercises of the shoulder and the elbow as tolerated during the fi rst postoperative week. Active mobilization is carried out from the second week. AP and lateral x-rays of the humerus are taken at 6 weeks, 3 months, and 6 months to assess healing and to look for secondary loss of alignment.

8

Pitfalls –

9

Pearls +

Pitfall 1

Pearl 1

The radial nerve is vulnerable during fracture reduction, tunneling, and plate insertion. Radial nerve function has to be evaluated before and after surgery. MIPO technique is not recommended in fractures with radial nerve palsy. Postoperative radial nerve palsy is an indication for radial nerve exploration.

To protect the radial nerve, the forearm must be kept in full supination during the surgery. This is because when the forearm is supinated, the radial nerve moves more laterally away from the distal humerus and so is less likely to be injured.

Pitfall 2

Pearl 2

In the distal incision, Hohmann retractors should not be used to retract the two halves of the brachialis after it is split along its midline as the radial nerve can be caught and compressed by the tip of the retractor during the retraction.

When exposing the distal shaft of the humerus in preparation for tunneling and plate insertion, the brachialis is split along its midline. The two halves of the brachialis are then separated using Army Navy retractors. The lateral half of the muscle protects the radial nerve while the medial half protects the musculocutaneous nerve (see Fig 12-9).

154

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12

8

Humerus, shaft

Pitfalls –

(cont)

9

Pearls +

(cont)

Pitfall 3

Pearl 3

The musculocutaneous nerve can be injured during the brachialis muscle splitting, tunneling, or plate insertion. This can be prevented by identifying the nerve before splitting the brachialis muscle. However, the sensory impairment resulting from injury of the musculocutaneous nerve is minimal and, in most cases, reversible.

To avoid injury to the radial nerve in the spiral groove, it is best not to insert screws in an anteroposterior direction in the midshaft of the humerus. If the midshaft area needs fi xation, screws should be applied monocortically whenever possible.

Pearl 4

It is easier to control the direction of the tunneler if one begins tunneling from the distal shaft under the brachialis muscle. To avoid going in the wrong direction, the tip of the tunneler must be in contact with the bone all the way to the proximal incision.

Pearl 5

Comminuted fractures are easier to reduce than transverse fractures. Segmental fractures are the most difficult as the surgeon needs to reduce two fractures. In order to reduce the middle segment, it may be necessary to overdistract the humerus to create the space to allow the middle segment to move back into position.

Pearl 6

Proximal and distal screw insertion should be in the center of the bone to prevent malalignment.

155

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10

Suggested reading

Apivatthakakul T, Arpornchayanon O, Bavonratanavech S (2005) Minimally invasive plate osteosynthesis (MIPO) of the humeral shaft fracture. Is it possible? A cadaveric study and preliminary report. Injury; 36(4):530–538. Fernandez Dell’Oca AA (2002). The principle of helical implants: unusual ideas worth considering. Injury; 33 Suppl 1:SA1–27. Gautier E, Sommer C (2003) Guidelines for the clinical application of the LCP. Injury; 34 Suppl 2:SB63–76. Hoppenfeld S, DeBoer P (1984). Surgical Exposures in Orthopaedics: the Anatomic Approach. Philadelphia: JB Lippincott:47–75. Krettek C, Schandelmaier P, Miclau T, et al (1997) Minimally invasive percutaneous plate osteosynthesis (MIPPO) using the DCS in proximal and distal femoral fractures. Injury; 28 Suppl 1:A20–30. Mast J, Jakob R, Ganz R (1989) Planning and Reduction Techniques in Fracture Surgery. Berlin Heidelberg New York: Springer-Verlag.

156

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Author

12.1 1

Theerachai APIVATTHAKAKUL

Humerus, shaft: wedge fracture, bending wedge—12-B2

Case description

a

2

b

Indication for MIPO

Conventional plating is not suitable for comminuted fracture of the humeral shaft because it requires extensive soft-tissue dissection

Fig 12.1-1a–b A 23-year-old male had a motorcycle accident and sustained a fracture of the shaft of his left humerus (12-B2) as well as a fracture of the proximal left femur. 2 years previously, the patient sustained bilateral femoral fractures which had been fi xed with retrograde femoral nails. This time, the fracture of the left femur has occurred at the level of the one of the proximal locking screws. The retrograde femoral nail was also broken at this level.

3

Patient positioning

Patient in supine position, with arm abducted 40°–60° on a radiolucent operating table.

and bone grafting. MIPO preserves the soft tissue and blood supply with rapid callus formation.

157

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12

4

Humerus, shaft

Surgical approach

b

a

Fig 12.1-2a–d a

Proximal incision between lateral border of biceps muscle and medial border of deltoid muscle. Distal incision between lateral border of biceps muscle and brachialis muscle. b Deep dissection at distal incision between biceps muscle and brachialis muscle. The musculocutaneous nerve has to be identified deep to the biceps muscle. c Biceps muscle and musculocutaneous nerve are retracted medially. The brachialis muscle is split longitudinally, along its midline to expose the anterior surface of humerus. Lateral half of brachialis muscle and radial nerve are retracted laterally. d Deep dissection at proximal incision between lateral border of biceps muscle and medial border of deltoid muscle down to the bone.

c

d

158

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12.1

4

Humerus, shaft: wedge fracture, bending wedge—12-B2

Surgical approach

(cont)

a

b

c

d

Fig 12.1-3a–d a

Tunneler is slipped through distal incision and passed proximally beneath brachialis muscle to create subbrachialis tunnel. b Tunneler is advanced until its distal end appears at the proximal incision. c Plate end is attached to tunneler by means of a suture. d Tunneler pulled back along with plate into subbrachialis tunnel.

159

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12

5

Humerus, shaft

Reduction and fixation

a

b

d

c

e

f

Fig 12.1-4a–f a

Plate is aligned in the center of distal humerus.

b–c Plate is fi xed to distal fragment with two screws. d

Indirect reduction by manual traction to restore length and rotation of humerus. Proximal fragment is fi xed with one screw.

e–f Image intensifier is used to check fracture reduction. If

reduction is satisfactory, fi xation is completed with three screws in each main fracture fragment.

160

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12.1

5

Humerus, shaft: wedge fracture, bending wedge—12-B2

Reduction and fixation

(cont)

a

b

Fig 12.1-5a–b a b

a

Two small incisions used in this MIPO technique. The radial nerve function is intact.

b

Fig 12.1-6a–b

Postoperative x-rays show fi xation of main fragments. 161

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12

6

a

Humerus, shaft

Rehabilitation

b

Fig 12.1-7a–b

X-rays at 6 months, the fracture has completely healed.

Fig 12.1-8

Functional result at 6 months.

162

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Author

12.2 1

Theerachai APIVATTHAKAKUL

Humerus, shaft: complex fracture, irregular—12-C3

Case description

a

2

b

Fig 12.2-1a–b A 41-year-old male, victim of motorcycle accident, with multifragmentary fractures of the left humeral shaft with proximal extension.

Indication for MIPO

The disadvantages of conventional plate fi xation for multifragmentary humeral shaft fractures include extensive soft-tissue dissection and the frequent need for bone grafting. MIPO avoids these. Proximal extension of the fractures makes it difficult for intramedullary nailing.

163

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12

3

Humerus, shaft

Patient positioning and plate contouring

Fig 12.2-2a–b a

a

4

a

b

Beach-chair position with arm lying free by the side. The image intensifier is positioned cranially. b The selected metaphyseal LCP is precontoured, using a plastic bone model or a locking proximal humeral plate (LPHP) as a template, to fit the anterolateral surface of the proximal humerus as well as the shaft.

Surgical approach

b

c

Fig 12.2-3a–d a

Skin markings for proximal and distal incisions. Distal incision between biceps and brachialis muscles. c Biceps muscle retracted medially. Brachialis muscle split longitudinally along its midline—the medial half retracted medially with musculocutaneous nerve and the lateral half retracted laterally with radial nerve. (Note the use of Army Navy retractors for retraction.) d Proximal deltoid splitting approach. b

d

164

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12.2

4

Humerus, shaft: complex fracture, irregular—12-C3

Surgical approach

(cont)

a

b

c

c

d

Fig 12.2-4a–f

Tunneling and plate insertion. Subdeltoid tunnel created with the plate. b Subbrachialis tunnel created with tunneler introduced through distal incision and passed proximally. c Tunneler passed through to proximal incision. d Distal end of plate tied to end of tunneler with suture. e Plate guided into subdeltoid and subbrachialis tunnels by withdrawal of tunneler. f Passage of plate monitored with image intensifier. a

e

f

165

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12

5

Humerus, shaft

Reduction and fixation

a

c

b

d

e

f

Fig 12.2-5a–i a–b Plate insertion com-

pleted and position confi rmed with image intensifier.

c–d Proximal fi xation using

one cancellous bone screw and one locking head screw (LHS).

e f

Temporary distal fi xation with K-wire following indirect reduction by manual traction under fluoroscopic guidance. When satisfactory alignment is achieved, fi xation is completed using four screws proximally and three screws distally.

166

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12.2

5

Humerus, shaft: complex fracture, irregular—12-C3

Reduction and fixation

(cont)

g

Fig 12.2-5a–i g h–i

6

(cont)

Wound closure. Postoperative x-rays show fi xation of main fragments.

h

i

Rehabilitation

Fig 12.2-7

Function at 6 months after

surgery. a

b

Fig 12.2-6a–b X-rays 6 months postoperatively show fracture union.

167

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12

Humerus, shaft

168

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Author

12.3 1

Theerachai APIVATTHAKAKUL

Humerus, shaft: complex fracture, spiral—12-C1

Case description

Fig 12.3-1a–b a

2

b

Indication for MIPO

A 46-year-old male with comminuted fractures of the shaft of the left humerus following a motorcycle accident.

3

Patient positioning

MIPO preserves soft tissue and blood supply at the fracture zone. This promotes fracture union and often avoids the need for bone grafting.

Fig 12.3-2

Patient lies supine on a radiolucent operating table with the left arm in 40°–60° abduction. 169

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12

4

Humerus, shaft

Surgical approach

a

b

c

Fig 12.3-3a–c a

Proximal incision between lateral border of biceps muscle and medial border of deltoid muscle. Distal incision between lateral border of biceps muscle and brachialis muscle. b Deep dissection at distal incision between biceps and brachialis muscles. Biceps muscle retracted medially and brachialis muscle split longitudinally along its midline.

5

c

Medial half of brachialis retracted medially with musculocutaneous nerve and lateral half retracted laterally with radial nerve. Deep dissection at proximal incision between lateral border of biceps muscle and medial border of deltoid muscle down to bone.

Tunneling and plate insertion

a

b

c

Fig 12.3-4a–c a

Tunneler slipped through distal incision and advanced proximally beneath brachialis muscle to create subbrachialis tunnel.

b c

Tunneler advanced until it reaches the proximal incision. Plate inserted into the tunnel from proximal to distal incision.

170

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12.3

6

Humerus, shaft: complex fracture, spiral—12-C1

Reduction and fixation

Fig 12.3-5a–b a

a

7

a

Reduction by manual traction followed by fracture stabilization using a narrow 12-hole DCP. b Small sutured wounds as a result of MIPO technique.

b

Rehabilitation

b

Fig 12.3-6a–b Postoperative x-rays show bridging of fracture by the narrow DCP.

a Fig 12.3-7 Radial nerve function is intact postoperatively.

b

Fig 12.3-8a–b X-rays at 3 months show callus formation.

171

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12

7

a

Humerus, shaft

Rehabilitation

(cont)

b

Fig 12.3-9a–b X-rays at 1 year show complete healing of the fracture.

Fig 12.3-10

The surgical scars at 1 year. Implant removal is unnecessary.

172

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Author

12.4 1

Theerachai APIVATTHAKAKUL

Humerus, shaft: wedge fracture, fragmented wedge—12-B3

Case description

Fig 12.4-1a–b

a

2

b

Indication for MIPO

In this case, the right humeral shaft fracture was treated by surgical fi xation—the indication being fractures in both upper limbs. MIPO

A 24-year-old female met with a motorcycle accident and sustained a right humeral shaft fracture (12-B3) and an undisplaced fracture of the distal left radius.

3

Patient positioning

Patient is placed on the radiolucent operating table in supine position with the arm abducted 40°–60°.

technique was selected as the choice of fi xation. Open reduction and internal fi xation for comminuted fractures of the humeral shaft require extensive soft-tissue dissection and often primary bone grafting. MIPO bridges the fracture zone and preserves the soft tissue and blood supply with rapid callus formation, and bone grafting is usually unnecessary.

173

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12

4

a

a

Humerus, shaft

Surgical approach

b

Fig 12.4-2a–b

b

Intraoperative x-rays are taken.

c

Fig 12.4-3a–d a

d

The proximal incision is marked between the lateral border of biceps muscle and medial border of deltoid muscle. The distal incision is marked between the lateral border of biceps muscle and brachialis muscle. b Deep dissection is performed at the distal incision between biceps muscle and brachialis muscle. The musculocutaneous nerve beneath the biceps muscle has to be identified. c The biceps muscle along with the musculocutaneous nerve is retracted medially. Longitudinal split of the brachialis muscle and deep dissection to the anterior surface of the humerus are carried out. The lateral half of brachialis muscle along with the radial nerve is retracted laterally. d Deep dissection is made at the proximal incision between lateral border of biceps muscle and medial border of deltoid muscle down to bone.

174

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12.4

4

Humerus, shaft: wedge fracture, fragmented wedge—12-B3

Surgical approach

(cont)

a

b

c

d

Fig 12.4-4a–d a

Two LCP drill sleeves are attached to one end of a 9-hole narrow LCP as a handle for plate insertion. b–c The LCP is passed through the distal incision toward the proximal humerus. d One of the drill sleeves is removed and then attached to the LCP proximally for manipulation of the plate in the tunnel.

175

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12

5

Humerus, shaft

Reduction and fixation

a

b

c

d

e

Fig 12.4-5a–e a

The plate is aligned in the center of the distal humerus and on its anterior surface. b The plate is fi xed to the distal fragment with one locking head screw (LHS) which is not fully tightened. c Indirect reduction is achieved by manual traction to restore the length and rotation of the humerus. Image intensifier must be used to check the alignment.

d e

When satisfactory alignment is achieved, the proximal fragment is fi xed with three LHS. Final incisions in the proximal and distal parts of the humerus.

176

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12.4

5

Humerus, shaft: wedge fracture, fragmented wedge—12-B3

Reduction and fixation

a

6

(cont)

b

Fig 12-4-6a–b

Postoperative x-rays show good fracture alignment.

Rehabilitation

Fig 12.4-7

Radial nerve function is intact.

a

b

Fig 12.4-8a–b Postoperative x-rays at 6 months. The fracture has healed completely with bridging callus.

177

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12

6

Humerus, shaft

Rehabilitation

a Fig 12.4-9a–b

(cont)

b

Small surgical scars and good function.

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13

1

Femur, proximal

Introduction

181

Cases 13.1

1.1

Classification

181

1.2

Indications and limitations for MIPO

182

2

Surgical anatomy

182

3

Aims of fracture reduction

184

4

Preoperative assessment and timing for surgery

185

5

Preoperative planning

186

6

OR set-up

186

6.1

Anaesthesia

186

6.2

Patient positioning and image intensifier

186

6.3

Implants and instruments

187

7

Operative procedure

188

7.1

Surgical approach

188

7.2

Fracture reduction

188

7.3

Fixation

188

8

Postoperative care

190

9

Pitfalls

190

10

Pearls

190

11

Suggested reading

192

Femur, proximal: extraarticular fracture, intertrochanteric—31-A3 and complex spiral diaphyseal fracture—32-C1

13.2

Femur, proximal: extraarticular neck fracture, subcapital with slight displacement—31-B1

13.3

193

199

Femur, proximal: extraarticular fracture, pertrochanteric, multifragmentary—31-A2

203

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Author

13

1

Suthorn BAVONRATANAVECH

Femur, proximal

Introduction

Fractures of the proximal femur occur predominantly in the elderly population with osteoporosis. Most of these are lowenergy injuries. In younger individuals, these fractures are less common and are usually the result of high-energy accidents. a

The treatment of proximal femoral fractures is usually surgical and various fi xation devices have been commonly used including the dynamic hip screw (DHS), the dynamic condylar screw (DCS), angled blade plates or condylar plates, and different types of proximal intramedullary nails. The choice of procedure depends on several factors, including: Fracture configuration Condition of the soft tissue Medullary canal size Patient’s condition Associated injuries Timing of the intervention Experience of the surgical team Facilities available 1.1

b

c

Fig 13-1a–c

31-A extraarticular fracture, trochanteric area. a 31-A1 pertrochanteric simple b 31-A2 pertrochanteric multifragmentary c 31-A3 intertrochanteric

a

b

c

Fig 13-2a–c

31-B extraarticular fracture, neck. 31-B1 subcapital, with slight displacement b 31-B2 transcervical c 31-B3 subcapital, displaced, nonimpacted a

Classification

According to the Müller AO Classification, the proximal femur is identified by the number 31 (Fig 13-1, Fig 13-2, Fig 13-3). Fractures of the proximal femur are divided into three groups: Type 31-A: extracapsular trochanteric fractures Type 31-B: intracapsular femoral neck fractures Type 31-C: intracapsular femoral head fractures

a

b

c

Fig 13-3a–c

31-C articular fracture, head. 31-C1 split (Pipkin) b 31-C2 with depression c 31-C3 with neck fracture a

181

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1

Introduction

(cont)

For the purpose of discussion in this chapter, subtrochanteric fractures are also included (Müller AO Classification: 32-A,B, or C) as the same principles and techniques apply when performing MIPO for these fractures.

considered, such as three cancellous bone screws or a DHS with a 2-hole side plate to fi x a femoral neck fracture and a long, broad plate (DCP, LC-DCP or LCP) to fi x the distal segmental fracture in the shaft. 1.2

Type 31-A trochanteric fractures may extend distally into the femoral shaft or they can occur in combination with an additional segmental fracture distally. Type 31-B intracapsular femoral neck fractures may be associated with ipsilateral femoral shaft fractures. Type 31-C fractures are intracapsular femoral head fractures. These uncommon injuries are rarely associated with fracture extension into the femoral shaft but may be associated with hip dislocation. Proximal femoral fractures with distal extensions or segmental fractures, if surgical stabilization is indicated, should whenever possible be managed with a single implant system such as the condylar plate, the DHS or DCS with a long side plate, the unreamed femoral nail (UFN) with various proximal locking devices, or the long proximal femoral nail (PFN). When this is not practical, two different implant systems may have to be

2

Indications and limitations for MIPO

The role of MIPO in the management of proximal femoral fractures is rather limited but suitable indications include complex fractures such as: Ipsilateral neck and shaft fractures Trochanteric fractures with extensions distally into the shaft Subtrochanteric fractures Complex fractures in the subtrochanteric region of the femur have a significant risk of nonunion and implant failure following conventional open plating techniques. By limiting the extent of medial and lateral dissection, MIPO reduces the incidence of nonunion and hence the need for primary or secondary bone grafting and the accompanying morbidity. To facilitate indirect reduction, the fractures should be relatively recent. Otherwise, soft-tissue contractures will make it difficult to obtain a satisfactory reduction.

Surgical anatomy

The important neurovascular structures lie along the medial aspect of the proximal femur and are usually not at risk since, in general, fractures of the proximal femur are approached from the lateral aspect during surgical fi xation. The proximal femur varies in size and shape, in ways that can be summarized as follows: the head is 40–60 mm in diameter making up 2/3 of a sphere; the femoral neck is about 5 cm in length; the neck shaft angle is 130º ± 7º with an anteversion of 10º–17º.

In displaced trochanteric and subtrochanteric fractures, the proximal fragment tends to be abducted, flexed, and externally rotated due to the attachments of the gluteus medius and minimus, psoas, and short external rotators respectively (Fig 13-4). Unless the action of these muscles is neutralized, malreduction will result.

182

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13

2

Femur, proximal

Surgical anatomy

(cont)

ration of the posterior cortex of the femoral neck. When using 135º angled implants, the entry point should be directly in the middle of the lateral cortex 2.5 cm distal to the vastus ridge at the level of the lesser trochanter which is situated posteromedially. This reduces the risk of perforation of the anterior cortex of the femoral neck (Fig 13-5).

The greater trochanter has a posterior flare and this must be taken into consideration when planning the entry point for the fi xed angle device. In the case of 95º angled implants, the entry point in the greater trochanter is in the anterior third of its lateral bulge 2 cm proximal to the vastus ridge. A more posterior entry point will result in perfo-

95º 135º

a

95º

b Fig 13-4

Deforming forces. In intertrochanteric or subtrochanteric fractures with intact lesser trochanter the proximal femur will deform in flexion, abduction, and external rotation.

135º

Fig 13-5a–b a

A 95º angled implant have to be inserted in the anterior third of the lateral aspect of the greater trochanter; 135º angled implants have to be inserted in the middle or posterior third of the lateral cortex in lateral view. b Proximal femur with insertion point of guide pin for 95º implant 2 cm above the vastus ridge, and the entry point for 135º implant 2.5 cm distal to the vastus ridge. 183

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3

Aims of fracture reduction

The aim of fracture reduction is to achieve a stable configuration before fi xation in order to reduce the complication rate as well as the risk of implant failure. Garden’s alignment index for displaced femoral neck fractures refers to the angle of the compression trabeculae on the AP x-ray view, relative to the longitudinal axis of the femoral shaft and the angle of the compression trabeculae on the lateral view relative to the femoral shaft. On the AP view, this angle should be 160º, while on the lateral view, it should be 180º. Acceptable reduction lies within the range 155º–180º on both views (Fig 13-6). Acceptable reduction minimizes nonunion and avascular necrosis. When Garden’s alignment index is less than 155º or more than 180º, the incidence of avascular necrosis increases from 7.3% to 53.8%. Valgus reduction of more than 20º also results in an increased rate of avascular necrosis. Failure to achieve a satisfactory alignment index by closed methods may be an indication for open reduction of the femoral neck fracture. In those cases of femoral neck fractures where there is posterior comminution, anatomical reduction may result in loss of the posterior buttressing effect, with subsequent loss of reduction and nonunion (Fig 13-7a). In such cases, valgus impacted reduction and fi xation with three parallel cancellous bone screws will increase the stability of the reduction (Fig 13-7b, Fig 13-8). In the case of trochanteric fractures, 60% are unstable due to loss of the medial buttress. In these unstable fractures, the aim of reduction is to have sufficient bony contact so that up to 75% of the load can be taken up by the bone, and only 25% will be taken up by the implant. Depending on the number of displaced fragments, closed reduction of the proximal femur to its anatomical shape is usually possible.

180°

150°

160°

a

b

Fig 13-6a–b Garden’s alignment index. In AP view, the angle of the compression trabeculae relative to the longitudinal axis of the femoral shaft should be 160°, while in the lateral view, it should be 180°.

184

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13

3

Femur, proximal

Aims of fracture reduction

a

(cont)

b

Fig 13-7a–b

Stability of reduction in femoral neck fractures. Anatomical reduction in a femoral neck fracture with posterior comminution will result in an unstable situation. b To obtain a stable reduction, the femoral neck is reduced in a valgus position over the stump of femoral neck a

4

Fig 13-8 This technique creates a stable reduction. The fi xation controls the shearing forces in vertical fractures such as in Pauwel III.

Preoperative assessment and timing for surgery

The earlier MIPO is carried out, the easier the reduction and hence the better the results. However, surgery should not be undertaken without proper assessment of the patient’s condition, including: Comorbidities Bone quality Hemodynamic stability Associated injuries Soft-tissue condition

185

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5

Preoperative planning

Preoperative planning should include the following: X-rays of the injured hip and femur in two planes X-rays of the contralateral, uninjured hip and femur in two planes X-rays of the pelvis with the contralateral, uninjured hip in internal rotation Preparing a preoperative graphic drawing with the fracture fragments reduced Selecting the appropriate implant and tracing the implant template over the graphic plan Determining the entry point and inclination of the blade or screw of the selected fi xed angle implant Determining the number, type, and order of application of the screws Selecting the best technique to obtain indirect fracture reduction

6

OR set-up

6.1

Anesthesia

Either general or regional anesthesia may be selected, the choice depending on the general condition and fitness of the patient. Positioning a patient with a proximal femoral fracture for regional anesthesia is likely to cause considerable pain and distress. 6.2

Patient positioning and image intensifier

A traction table may be used if closed reduction of the fracture is possible and the reduction can be maintained throughout the procedure (Fig 13-9a). Otherwise, a radiolucent operating table would be preferable. The radiolucent operating table makes it easier to carry out maneuvers to obtain fracture reduction. It also facilitates the checking of limb length, axial and rotational alignment following fracture reduction and provisional fi xation. Set-up time is also shorter.

When a radiolucent operating table is used, the patient is positioned supine with the uninjured extremity supported on a stirrup with the hip in flexion and abduction. Alternatively, the contralateral uninjured limb is also prepared and draped free under sterile conditions so that comparison can be made between the operated and uninjured sides during surgery. An image intensifier should be available and positioned to take AP and lateral images of the hip and femur (Fig 13-9b–c). Pilot images should be checked before cleaning and draping. Before starting the operation, the length, axis, and rotation of the uninjured limb should be checked using the various methods of measurement such as the meterstick technique, cable technique, hip rotation test, and the lesser trochanteric shape sign, respectively (Chapter 10 Complications and solutions). This information is used for comparison with the fractured side during the surgery.

186

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13

6 6.3

Femur, proximal

OR set-up

(cont)

Implants and instruments

Trochanteric fractures with distal extensions into the femoral shaft and complex subtrochanteric fractures are good indications for the MIPO technique. The longer the length of the fracture, the more appropriate the application of the MIPO technique becomes. Both the 95º condylar plate and the DCS are suitable for use in MIPO of proximal femoral fractures. The condylar plate requires 3-plane alignment whereas the DCS requires only 2-plane alignment—sagittal alignment with the DCS can be

a

accomplished by rotating the plate–screw construct after insertion. In either case, a side plate of adequate length must be selected. In ipsilateral neck and shaft fractures of the femur, if MIPO is selected as the fi xation method, a DHS with a long side plate that has at least 4–5 holes extending beyond the distal shaft fracture should be selected. The external fi xator or large distractor may be required for indirect fracture reduction.

b

c

Fig 13-9a–c a

Patient is positioned supine on a traction table with the C-arm between the legs. b–c The patient is placed on a radiolucent operating table with the uninjured leg in hemilithotomy position in order to allow the image intensifier to take AP and lateral views of the injured limb. 187

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7 7.1

Operative procedure Surgical approach

With the patient supine and a support beneath the knee, longitudinal traction is applied manually to the limb to realign the thigh. The patella should be directed anteriorly. A straight lateral incision is made, starting at the tip of the greater trochanter and extending distally for 5–8 cm. The tensor fasciae latae is split and the vastus lateralis is reflected anteriorly for about 1 cm from the linea aspera. The vastus ridge is identified for the entry point of a guide wire (Fig 13-10). 7.2

Fracture reduction

If the proximal fracture fragment is short, a Schanz screw is inserted into this fragment to act as a reduction aid in order to counteract the pull of the attached muscles and to hold the fragment in a reduced position so that it has a normal AP appearance on the image intensifier (Fig | Anim 13-11a). In long spiral fractures, passing a cerclage wire through a small incision may be necessary to achieve and maintain reduction. 7.3

Fixation

First, a guide wire is inserted anteriorly in line with the axis of the femoral neck to mark the anteversion (Fig | Anim 13-11b). A second guide wire is then driven into the greater trochanter, parallel to the fi rst guide wire and marking the direction of the canal for the blade of the condylar plate or the DCS screw. An image intensifier is used to confi rm correct positioning of the guide wires in the AP and lateral views. The canal for the blade or the DCS screw hole is then created. If a DCS screw is used, the condylar screw hole is tapped if necessary, and the screw inserted. A submuscular extraperiosteal tunnel deep to the vastus lateralis is prepared and the plate of the condylar plate or DCS is

95°

135°

a

b

Fig 13-10a–b

Surgical approach. a For 95° implants, a straight lateral incision starts from the tip of greater trochanter and extends distally 5–8 cm. b For 135° implants, the incision starts 4–5 cm below the greater trochanter.

inserted into the prepared tunnel with the blade of the condylar plate or the barrel for the DCS screw facing laterally (Fig | Anim 13-11c). The plate is next rotated 180° and the proximal femoral fragment is then brought into correct alignment with the help of the Schanz screw acting as a joystick. The blade of the condylar plate is then inserted into the prepared canal (Fig | Anim 13-11d) or the barrel of the DCS side plate slipped over the DCS (screw). If the angle of insertion is correct, the side plate will align with the femoral shaft (Fig | Anim 13-11e). A screw is then used to fi x the plate to the distal main fracture fragment. The length, rotation, and axial alignment of the femur are then checked. If correct, the rest of the screws are inserted. If possible, four screws each should be inserted percutaneously with the help of the image intensifier into the proximal and distal main fragments in a near-far configuration for optimal stability. A specially designed drill guide is used for drilling, tapping, and screw insertion.

188

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13

7

Femur, proximal

Operative procedure

(cont)

Animation

a

b

c

d

Fig | Anim 13-11a–e

MIPO of proximal femoral fractures using the 95° condylar plate. The Schanz screw is inserted to counteract the muscle pull and to keep the proximal femur in AP position. Care must be taken that the Schanz screw will not interfere with the chiseling of the canal. b A guide wire is inserted at a 95° angle in the AP view with correct anteversion in the lateral view. The position of the guide pin is checked using image intensifier. c After the canal has been prepared, the side plate of the condylar plate is slipped under the vastus lateralis muscle with the blade facing laterally. The guide wire is kept as a reference for the direction of canal. d–e The blade is turned 180° and inserted into the prepared canal with a previously attached plate holder. In some cases, the Schanz screw can be used to manipulate the proximal femur during blade insertion. a

e

189

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7 8

Operative procedure Postoperative care (cont)

The patient remains in bed for 1 or 2 days with the hip and knee in slight flexion. To prevent pulmonary complications, the patient is mobilized as soon as possible—partial weight

9

Pitfalls –

bearing with a walker or crutches is encouraged, the amount of weight bearing on the injured limb depending on the fracture type and stability of fracture fi xation.

10

Pearls +

Pitfall 1

Pearl 1

Fracture reduction on a traction table is difficult to achieve in complex or segmental fractures. Assessment of limb length, rotation, and axial alignment is also difficult and may cause malalignment.

Fracture manipulation and reduction is easier when the operation is carried out on a radiolucent operating table and both lower limbs prepared and draped. The intact limb can then be used for comparison with the injured limb during the surgery.

Pitfall 2

Pearl 2

Placing the guide wire incorrectly with respect to the fi xed angle of the implant used will lead to improper placement of the implant resulting in complications such as too much anteversion or retroversion, varus or valgus deformity of the head-neck fragment or perforation of the cortex of the femoral neck (Fig 13-12).

The correct orientation of the implant in the femoral neck is the key to successful surgery. To facilitate the insertion of the directional guide wire and preparation of the canal for the blade of the condylar plate or the dynamic condylar screw, a Schanz screw is driven into the femoral neck below the defi ned position for blade or screw insertion and used as a joystick to hold the proximal fragment in the correct position. Once the proximal femur is aligned and controlled on the AP view, it is easier to place the guide wire in the correct position.

Pitfall 3

When using the chisel to create the canal for the blade of the condylar plate, the handle of the slotted hammer must be used as a directional guide for the antecurvature of the femoral shaft in order to avoid malalignment of the side plate of the condylar plate on the femur.

190

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13

9

Femur, proximal

Pitfalls –

(cont)

10

Pearls +

(cont)

Pearl 3

a

b

c

Varus malposition of the proximal femoral fragment may occur when a 95° condylar plate is used. During insertion of the blade into the prepared canal in the proximal femoral fragment, the direction of the blade and canal frequently do not correspond. The blade has a tendency to go in the wrong direction and create a false passage resulting in the proximal fragment being fi xed in the varus position. The reason for this is that the lateral thigh muscles tend to push the blade plate into a varus position. This complication can be avoided by using the Schanz screw in the proximal fragment as a joystick to bring it into proper alignment to the blade during blade insertion. Also, the guide pin used initially to guide the direction of the seating chisel should be left in place to guide the direction of blade insertion. Another useful tip is to use a short blade of 50–60 mm length which makes it easier to turn into the prepared canal.

d

Fig 13-12a–d

Improper placement of the condylar plate may result in various complications: a If the blade is inserted with too much anteversion, perforation of the anterior cortex of the femoral neck by the blade may occur. b–c Incorrect angle of insertion of the blade of the condylar plate in the AP view will result in varus or valgus deformity of the proximal head-neck fragment once the side plate is aligned to sit on the lateral cortex of the femoral shaft. d If the blade is inserted with too much retroversion, perforation of the posterior cortex of the femoral neck can take place. If the blade is inserted too proximally, it may perforate the superior cortex of the neck.

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11

Suggested reading

Hoffmann R, Haas NP (2000) Femur: proximal. Ruedi T, Murphy W, (eds) AO Principles of Fracture Management. Stuttgart New York: Georg Thieme Verlag, 441–467. Kinast C, Bolhofner BR, Mast JW, et al (1989) Subtrochanteric fractures of the femur. Results of treatment with the 95 degree condylar blade-plate. Clin Orthop Relat Res; 238:122–130. Krettek C, Schandelmaier P, Miclau T, et al (1997) Minimally invasive percutaneous plate osteosynthesis (MIPPO) using the DCS in proximal and distal femoral fractures. Injury; 28 Suppl 1:20–30. Siebenrock KA, Müller U, Ganz R (1998) Indirect reduction with a condylar blade plate for osteosynthesis of subtrochanteric femoral fractures. Injury; 29 Suppl 3:7–15.

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Author

13.1 1

Suthorn BAVONRATANAVECH

Femur, proximal: extraarticular fracture, intertrochanteric— 31-A3 and complex spiral diaphyseal fracture—32-C1

Case description

a

b

c

Fig 13.1-1a–c A 40-year-old male motorcycle accident victim sustained a Gustilo type II open fracture of the proximal left femur and a closed midshaft fracture of the ipsilateral tibia. Initial treatment consisted of debridement of the open fracture and closed reduction of the left tibial fracture, with immobilization in short leg slab. The patient was transferred 7 days later for defi nitive fracture fi xation. He had no other injury. X-rays of left femur showed an intertrochanteric fracture with extension into the femoral shaft and an additional segmental fragment. No fever or sign of local infection was evident.

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13

2

Femur, proximal

Indication for MIPO

Reconstruction by intramedullary nailing may be adequate but technically problematic due to the short proximal fragment, which may result in varus deformity and an unstable fi xation. A special long proximal femoral nail (PFN) is another option and provides better fi xation. However, it was not available as a standard implant. Bridge plating—with a condylar plate or a dynamic condylar screw (DCS)—is better for stabilization of intertrochanteric fractures with extension into the shaft using the MIPO technique. This gives a stable fi xation with minimal soft-tissue dissection.

Fig 13.1-2a–b Preoperative planning determines proper size of implant. In this case, a condylar plate (70 mm blade length, 16 holes) is selected.

3

a

b

Positioning

The patient is positioned supine on the radiolucent operating table with the uninjured extremity supported on a stirrup with the hip in flexion and abduction. The buttock on the injured side is elevated by a rolled towel. The image intensifier is positioned between the lower limbs to check AP and lateral projections. It is recommended to position the C-arm before draping.

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13.1

4

Femur, proximal: extraarticular fracture, intertrochanteric—31-A3 and complex spiral diaphyseal fracture—32-C1

Surgical approach

a

b

Fig 13.1-3a–b The approach was through the original wound. The tensor fasciae latae and vastus lateralis were split down to bone. The vastus ridge was identified— the landmark for insertion of the guide pin being 2 cm proximal to the vastus ridge.

5

Reduction

a

b

c

Fig 13.1-4a–c a–b

The proximal femur is manipulated by either a bone hook or a Schanz screw to realign the hip in a neutral position. The guide pin is inserted at a 95º angle with 5º anteversion. Note that the guide pin is to be placed 1 cm proximal to the planned entry point for the seating chisel which prepares the canal for the blade. Record the AP projection that shows the correct position of the guide pin.

c

The image intensifier is rotated to obtain a lateral projection of the hip. In case of malposition of the guide pin, a second pin is inserted using the fi rst pin as a reference.

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13

5

Femur, proximal

Reduction

a

(cont)

b

Fig 13.1-5a–d a

The canal for the blade is prepared parallel to the guide pin in AP and lateral projections up to the length of the blade. As the seating chisel is being inserted, it is essential to keep in mind the antecurvature of the femoral shaft so that the plate is subsequently aligned to the shaft. b The tunnel for the side plate is prepared deep to the vastus lateralis. The condylar plate is then introduced into the prepared tunnel with the blade pointing laterally.

c

d

c

The plate is then rotated 180º and the blade inserted into the prepared canal. It is useful to leave the guide pin as a directional guide for the insertion of the blade. d The blade is inserted into the femoral neck in slight valgus. The key to success is the placement of the blade in the correct position as shown in the AP and lateral views on the image intensifier. Next the fracture is reduced by manual traction and the side plate is aligned with the femoral shaft. 196

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13.1

6

Femur, proximal: extraarticular fracture, intertrochanteric—31-A3 and complex spiral diaphyseal fracture—32-C1

Fixation

a

b

Fig 13.1-6a–d a

b

To improve stability, an additional fully threaded cancellous bone screw is used to fi x the proximal fragment to the side plate. The side plate should be aligned with the lateral cortex of the femoral shaft. Longitudinal traction is applied manually with the knee in flexion and preliminary fi xation of the distal fragment is obtained with a screw fi xed monocortically. Limb length and hip rotation are checked against the values obtained preoperatively from the uninjured side. Additional screws are inserted bicortically if length and alignment are satisfactory.

c

d

c–d

Percutaneous lag screw fi xation is used in case of a displaced middle fragment. A Hohmann retractor is useful for reduction. 197

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13

7

Femur, proximal

Rehabilitation

MIPO technique provides enough stability for postoperative range of hip and knee motion with partial weight bearing with crutches or a walker. Callus formation is commonly seen with relative stability and intact vascularity within 4–6 weeks.

a

b

c

Fig 13.1-7a–c a

Immediate postoperative x-ray shows proper alignment with gaps between the fragments in the comminuted zone.

b

X-ray 3 months postoperatively shows callus bridging fragments.

c

X-ray 6 months postoperatively shows complete consolidation of comminuted fracture area.

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Author

13.2 1

Suthorn BAVONRATANAVECH

Femur, proximal: extraarticular neck fracture, subcapital with slight displacement—31-B1

Case description

A healthy 65-year-old male fell down a fl ight of stairs and injured his left hip. He was unable to bear weight after the fall. There was no other injury.

2

Indication for MIPO

Stable femoral neck fractures may be treated by simple implants such as three parallel cancellous bone screws or a dynamic hip screw (DHS). If it is decided to use the DHS instead of the conventional method, it is advantageous to perform the internal fi xation using a smaller incision. As most of these fractures occur in elderly patients, a less invasive surgical technique has the advantage of reducing operating time and blood loss. This MIPO technique is also applicable to stable trochanteric fractures that can be satisfactorily reduced by closed reduction techniques.

Fig 13.2-1 X-ray shows an impacted neck fracture of the left femur.

3

Positioning

In a stable femoral neck fracture, surgery is performed on a traction table in order to maintain fracture alignment. In the case of displaced fractures, closed manipulation and reduction may be required. Image intensifier shows AP and lateral views.

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13

4

Femur, proximal

Reduction

a

b

Fig 13.2-2a–b a

Following closed reduction, the 135º angle guide with the guide pin inserted is placed on the skin and the position checked with an image intensifier, making sure that the side plate of the guide is parallel to the femoral shaft and the guide pin lies along the calcar. b AP x-ray shows the point of entry for the guide pin.

5

Fixation

a

b

c

Fig 13.2-3a–i a–b

An incision of approximately 3 cm is made at the site of guide pin insertion. The tensor fasciae latae is incised and the vastus lateralis muscle is elevated. The second guide pin is drilled through lateral cortex, parallel to the angle guide in AP projection, taking into consideration the 15º anteversion of the femoral neck.

c

Measurement of length of the guide pin. The triple reamer is set according to length of screw to be used.

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13.2

5

Femur, proximal: extraarticular neck fracture, subcapital with slight displacement—31-B1

Fixation

(cont)

d

e

Fig 13.2-3a–i d e f

g g h–i

f

(cont)

A Steinman pin of 4.5 mm is inserted parallel to the guide pin to maintain the position of the fracture during reaming with triple reamer. The DHS is inserted after reaming. The Steinman pin is replaced by a 6.5 mm cancellous bone screw. A subvastus tunnel is created and the side plate is slipped beneath the muscle with the barrel facing laterally.

h

i

The side plate is rotated 180º and the barrel inserted over the end of DHS . Skin incision is closed with staples.

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13

6

Femur, proximal

Rehabilitation

Fig 13.2-4 Postoperative x-ray shows stable fi xation, allowing the patient to start ambulation with partial weight bearing.

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Authors

13.3 1

Theerachai APIVATTHAKAKUL, Suthorn BAVONRATANAVECH

Femur, proximal: extraarticular fracture, pertrochanteric, multifragmentary—31-A2

Case description

a

2

b

Indication for MIPO

As the fracture is multifragmentary, indirect reduction with relative stable fi xation is recommended. Open and direct reduction should be avoided because of the higher risk of complications such as delayed union and infection due to the disturbance in blood supply. In the preoperative planning, various treatment options are considered. The proximal femoral nail (PFN) and the dynamic hip screw (DHS) are deemed

Fig 13.3-1a–b A 24-year-old male met with a motorcycle accident and sustained closed multifragmentary fractures of the right femur at the level of the lesser trochanter with extension down to the proximal shaft. No other injury was sustained.

3

Positioning

The patient is positioned supine on the radiolucent operating table. The length of the uninjured limb is measured from the tip of the greater trochanter to the upper pole of the patella. External and internal rotation of the intact hip with the hip and knee flexed to 90° are recorded for intraoperative comparison.

unsuitable as the lateral cortex is fractured at the entry point. As the point of insertion for the 95° angled implants is intact, either the condylar plate or the dynamic condylar screw (DCS) may be used. The DCS is selected as it is the stronger implant and technically easier to apply.

The knee on the injured side is flexed with a support and the patella aligned in neutral position. The uninjured extremity is supported on a stirrup with the hip in flexion and abduction. The image intensifier is positioned between the lower limbs to check AP and lateral projections. It is recommended to set the position of the C-arm before draping.

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13

4

Femur, proximal

Surgical approach

A 5 cm incision is made from the tip of the greater trochanter and extending distally. The tensor fasciae latae is split and the vastus lateralis elevated. The periosteum is kept intact. The insertion point 2 cm proximal to the vastus ridge is identified. A Schanz screw is inserted into the proximal femoral

a

fragment to act as a joystick for manipulation to counteract the muscle forces. A guide pin is driven along the anterior aspect of the femoral neck to mark the degree of anteversion. The guide pin for the DCS is inserted in a 95° angle to the shaft and parallel to anterior guide pin. The pin location is checked in AP and lateral views with the image intensifier.

b

Fig 13.3-2a–c a

c

Incision is performed from tip of greater trochanter and guide pin is placed into the correct position. b Tunnel for side plate is prepared by using a tunneler. c Manual traction is performed to reduce the fracture and locate the site of the incision that marks the distal end of the side plate.

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13.3

5

Femur, proximal: extraarticular fracture, pertrochanteric, multifragmentary—31-A2

Reduction

With the guide pin in the correct position, the triple reamer is used to prepare the canal for the DCS screw and the barrel of the side plate. The DCS screw is inserted after tapping. A 16-hole DCS side plate with the barrel pointing laterally is inserted into the prepared submuscular tunnel. The plate is then rotated 180º and the plate barrel slipped over the distal end of the DCS.

6

Fixation

If the DCS is placed in the correct orientation, the side plate will align with the lateral cortex of the femoral shaft. Adjustments in the sagittal plane can be made by rotating the plate–screw construct. Longitudinal traction of the thigh is then carried out manually with the knee in 90° flexion and the patella in neutral position. Preliminary distal fi xation is carried out with a screw inserted monocortically. The limb length and rotation are checked and compared with the values obtained preoperatively from the uninjured side.

Fig 13.3-3 X-ray shows fi xation by DCS in proper alignment. As the medial side is undisturbed, primary bone graft is not necessary.

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13

7

Femur, proximal

Rehabilitation

Fig 13.3-4a–c a

a

b

c

Postoperative x-ray shows proper alignment with callus formation. b–c X-rays 2 months (b), and 4 months (c) postoperatively show progressive bone healing with callus formation.

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14

Femur, shaft

1

Introduction

209

Cases

1.1

Classification

209

14.1

1.2

Indications and contraindication for MIPO

210

2

Surgical anatomy

210

2.1

Blood supply to the femoral shaft

210

2.2

Shape of the femur

210

3

Preoperative assessment

212

3.1

Timing of surgery

212

4

Preoperative planning

212

5

OR set-up

213

5.1

Anesthesia

213

5.2

Patient positioning and image intensifier

213

5.3

Implants and instruments

213

6

Operative procedure

214

6.1

Indirect reduction with an external fixator followed by plate fixation

6.2

Femur, shaft: wedge fracture, fragmented wedge—32-B3

14.2

221

Femur, shaft: wedge fracture, spiral wedge—32-B1

225

Teaching video on DVD-ROM 14

Femur, shaft—lateral approach

214

Indirect reduction using the selected precontoured plate as a reduction tool

214

7

Postoperative care

218

8

Pitfalls

218

9

Pearls

218

10

Suggested reading

220

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Author

14 1

Suthorn BAVONRATANAVECH

Femur, shaft Introduction

The vast majority of fractures of the shaft of the femur today are treated by internal fi xation. The exception may be children and young adolescents, but even in this age group, there is a growing tendency toward surgical stabilization. Traditionally, femoral shaft fractures in adults were treated by either closed intramedullary nailing or open reduction with plate fi xation. Although each method had its advantages and disadvantages, the choice of the method of fi xation really depended on the experience of the surgeon, his preference and the facilities available. However, with the advent of the antegrade locked intramedullary nail inserted by closed means, conventional open plating as a method of fi xing femoral shaft fractures gradually became less popular. There were several reasons for this: plating was a much larger procedure requiring extensive exposure; there was frequent need for bone grafting, greater blood loss, higher incidence of infection, significant rate of implant failure and nonunion, and a greater likelihood of loss of knee motion.

a

b

c

30°

Fig 14-1a–c

32-A simple fracture. 32-A1 spiral b 32-A2 oblique (≥ 30º) c 32-A3 transverse (< 30º) 32-A (1–3).1=subtrochanteric zone a

a

b

c

Fig 14-2a–c

32-B wedge fracture. 32-B1 spiral wedge b 32-B2 bending wedge c 32-B3 fragmented wedge 32-B (1–3).1=subtrochanteric zone a

With the introduction of indirect fracture reduction and minimally invasive plate osteosynthesis (MIPO), many of the disadvantages of conventional plating of femoral shaft fractures were overcome. In fact, for certain fracture configurations, MIPO may have a distinct advantage over intramedullary nailing. However, it should be emphasized that this technique is not easy but attention to detail will help to avoid some of the difficulties associated with this method. 1.1

a

Classification

b

c

Fig 14-3a–c

In the Müller AO Classification,the femoral shaft is designated by the number 32. There are three types of fracture morphology: type 32-A is a simple fracture with a single fracture line,

32-C complex fracture. 32-C1 spiral b 32-C2 segmental c 32-C3 irregular a

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1

Introduction

(cont)

type 32-B is a wedge fracture and type 32-C is a multifragmentary fracture (Fig 14-1, Fig 14-2, Fig 14-3).

1.2

Type 32-B and type 32-C fractures, especially those with proximal extension into the trochanteric area or distal extension into the condylar area Fractures in the pediatric population with open epiphyses Femoral fractures with narrow or deformed intramedullary canals Periprosthetic fractures Ipsilateral neck and shaft fractures where the neck fracture is treated using a separate implant Fractures associated with lung contusion

In general, for type 32-B and type 32-C fractures, if the choice of fi xation is plating, the principle of bridge plating should be applied as the aim is relative stability to promote indirect fracture healing by callus formation. In type 32-A fractures, the standard teaching is accurate reduction and stable fi xation to achieve direct fracture healing using the principle of interfragmentary or axial compression. This may be possible using MIPO techniques although it is sometimes necessary to make a small incision directly over the fracture site to obtain accurate reduction which is then maintained using a variety of temporary holding devices before defi nitive plate fi xation takes place.

2 2.1

Indications and contraindication for MIPO

MIPO should not be performed if surgery is delayed for more than 2 weeks following the injury as soft-tissue contracture renders indirect reduction of the fracture impractical.

Surgical anatomy Blood supply to the femoral shaft

The blood supply of the femoral shaft is derived from two main sources: The inner 2/3 of the cortex derives its blood supply from the nutrient artery which arises from the second perforating artery and enters the bone proximally and posteriorly along the linea aspera, while the outer 1/3 of the cortex is supplied by the periosteal arteries which are derived from the surrounding muscles supplied by the perforating arteries (Fig 14-4). Following displaced fractures, the circulatory pattern of the femoral shaft is drastically altered due to disruption of the medullary blood supply. However, the periosteal blood vessels are seldom extensively stripped because of their perpendicular orientation to the cortical surface. Until the recovery of the endosteal circulation, the periosteal vessels are

the main source of blood supply around the fracture zone; hence the importance of preserving the periosteal vessels and the perforating arteries. By placing the plate in a submuscular, extraperiosteal tunnel, MIPO minimizes the damage to these vessels and helps to improve the results of internal fi xation of the femur using plates. 2.2

Shape of the femur

The femoral shaft has an antecurvature with a radius of about 1.5 m. Also to be noted are the lateral cortical flares 2–3 cm distal to the vastus ridge and at the distal metaphyseal area. These features must be taken into consideration when long plates are used as precontouring will be required (Fig 14-5, Fig 14-6).

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14

2

Femur, shaft

Surgical anatomy

(cont)

a

b Fig 14-5a–b

Relation between plate application and lateral aspect of femur. a Shape of a 18-hole LC-DCP, placed on the lateral aspect of the femur. b If a long plate is applied extending from the trochanteric to the lateral condylar region of the femur, precontouring of the plate is required to accommodate the proximal and distal lateral flares.

a

b Fig 14-6a–b

Techniques to maintain antecurvature of the femur. A 14-hole LC-DCP with a slightly convex shape, fi xed on the anterolateral surface of the femur by oblique screw fi xation at 40º to maintain antecurvature of the femur. This technique can be used in the midshaft area but should not be used for a plate that extends from the proximal to the distal metaphysis. b An anatomically designed, sagittally bent 16-hole LCP applied on lateral aspect of femur to maintain the antecurvature of the femur. a

Fig 14-4

Periosteal circulation along the femoral shaft.

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Preoperative assessment

Fractures of the femoral shaft are usually the result of highenergy accidents. Hence, the hemodynamic status of the patient as well as the possibility of associated injuries should be carefully evaluated. Head, chest, and visceral injuries may be present. Ipsilateral femoral neck fractures, knee injuries and ipsilateral tibial fractures are not uncommon. The neurovascular status of the affected limb as well as the condition of the skin and soft tissues must be assessed. All patients with fractures of the femoral shaft should have AP and lateral x-rays of the entire femur with separate examinations of the pelvis, ipsilateral hip, knee, and tibia if indicated. X-rays of the contralateral uninjured femur should also be taken for the purpose of preoperative planning.

Timing for surgery

Where indicated, fractures of the femoral shaft should be fi xed as soon as possible. This is especially so in cases of multiple trauma as early stabilization reduces the incidence of acute respiratory distress syndrome. Even for isolated fractures, early fi xation has many advantages: hemorrhage and swelling are less, muscle spasm and contracture are less pronounced making indirect reduction easier to achieve, and the patient can be mobilized early so that the period of hospitalization is shortened.

Preoperative planning

* Plate span ratio =

density 0.5

Plate-screw density 0

Plate length*

A plate span ratio* of 3 for multifragmentary fractures and of 8–10 for simple fractures with a plate-screw density of less than 0.5 serve as a guide for selecting the appropriate length of plate.

Plate-screw

Fracture length*

Fig 14-7

Plate-screw density 0.39

The contralateral uninjured femur should be assessed for subsequent intraoperative comparison during MIPO.

6 holes 3 screws

Preoperative planning should include preparation of a graphic plan and reduction tactics, selection of the appropriate length and type of the plate, assessment of the need for precontouring, and the type and number of screws to be used and their order of insertion (Fig 14-7).

6 holes 0 screws

4

3.1

Plate-screw 6 holes 4 screws

3

density 0.67

Plate length Fracture length

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14

5 5.1

Femur, shaft

OR set-up Anesthesia

Either general or regional anesthesia may be used, depending on the condition of the patient. 5.2

Patient positioning and image intensifier

The operation is carried out with the patient in a supine position on a radiolucent operating table. A supporting pad is placed under the knee to maintain it in 40º–60º flexion with the patella pointing upward in neutral position (Fig 14-8). The limb is prepared and draped from the level of the iliac crest to below the knee. If desired, the opposite uninjured limb is also prepared and draped free to allow intraoperative comparison with the fractured side. The image intensifier is positioned on the opposite side of the operating table. The C-arm should be able to be tilted so that the x-ray beam is perpendicular to the axis of the femoral shaft and must be able to be moved so that images from the hip to the knee can be taken. All these should be checked before preparation and draping. 5.3

The plate should be long enough to allow the insertion of at least three screws each into the proximal and distal main fracture fragments. A plate span ratio of 3 for multifragmentary fractures and of 8–10 for simple fractures with a plate-screw density of less than 0.5 serve as a guide for selecting the appropriate length of plate. Usually, plates with 16 or 18 holes are used for MIPO of femoral shaft fractures. Preoperative contouring of the plate using a plastic bone model or x-rays of the contralateral uninjured femur as a template is usually necessary, especially when using conventional plates. The precontoured plate is then sterilized for the operation. A precontoured plate can also be used as an aid for indirect fracture reduction. The external fi xator set or large distractor should also be prepared if needed for indirect reduction. Instruments that are helpful in fracture reduction, such as cerclage wires, collinear reduction clamps and manipulators should also be made available when needed.

Implants and instruments

The broad LCP as well as the broad DCP and LC-DCP can be used for MIPO of femoral shaft fractures. In the presence of osteoporosis and in periprosthetic fractures, LCP are preferred. A new LCP for the femoral shaft which has a sagittal bend to conform to the antecurvature of the femur is now available (see Fig 14-6b). In fractures with extension proximal to the trochanteric region or distal to the condylar area, a condylar plate or a dynamic condylar screw (DCS) may be used.

Fig 14-8

The patient is positioned supine with the knee in 40º–60º flexion and the patella pointing anteriorly in neutral position.

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6

Operative procedure

In general, there are two methods of performing MIPO of femoral shaft fractures. In the fi rst method, the fracture is indirectly reduced with an external fi xator or large distractor before plate fi xation is carried out. In the second method, the selected precontoured plate is used as reduction tool to achieve indirect reduction followed by fracture fi xation. 6.1

Once the fracture is reduced satisfactorily, the reduction is maintained by locking the two Schanz screws with a third tube, using clamps that have previously been assembled on the Schanz screws. Next, two incisions are made over the lateral aspect of the femur, corresponding to the proximal and distal ends of the plate. The plate is then introduced into a submuscular extraperiosteal tunnel. The plate is temporarily held on to the lateral cortex of the femur with monocortical screw insertion (cortex screws) through the most proximal and distal holes. The position of the plate in relation to the bone is checked with the image intensifier and, if satisfactory, the fi xation is completed with the appropriate screws.

Indirect reduction with an external fixator followed by plate fixation

This method is suitable for use with all kinds of plate. The main steps of the technique are as follows (Fig 14-9): Two Schanz screws are inserted into the anterior aspect of the femur, one in the proximal fracture fragment and the second in the distal fragment. The Schanz screws should be inserted close to the fracture site for better control. Manipulation and reduction of the fracture are then carried out using the Schanz screws as joysticks, with the aid of the image intensifier. To avoid direct exposure of the surgeon’s hands to radiation, manipulation of the Schanz screws is done via two tubes connected by means of clamps.

6.2

Indirect reduction using the selected precontoured plate as a reduction tool.

The following is a description of the main steps in the surgical fi xation of a femoral shaft fracture with a precontoured broad LC-DCP using the MIPO technique: The patient lies supine on a radiolucent operating table with the knee flexed to 40–60º with the aid of a supporting pad and the patella pointing upward in neutral position. The limb is prepared and draped.

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14

6

Femur, shaft

Operative procedure

(cont)

a

b

d

e

c

Fig 14-9a–e

Indirect reduction technique of femur using tubular external fi xator. Schanz screws are placed into the proximal and distal fracture fragments in an AP direction close to fracture site. Each Schanz screw is fi xed with a clamp and connected to a long tube to protect surgeon’s hands from radiation exposure from the C-arm. Note that an empty clamp has been preassembled on each Schanz screw. b–c The Schanz screws are used as manipulators until fracture reduction is achieved as shown on the image intensifier. d Once reduction is achieved, a long tube is inserted into preassembled clamps on the Schanz screws and locked. The external fi xator will maintain fracture reduction during plate application. e An LCP is introduced percutaneously using a threaded drill guide as a handle. a

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6

Operative procedure

(cont)

The positions of the proximal and distal incisions, which correspond to the proximal and distal ends of the plate, are marked on the skin using the selected plate as a template after applying traction to the femur to restore length and alignment (Fig 14-10). The proximal and distal incisions are made. Each incision is 5–7 cm in length and is carried sharply through the iliotibial tract and vastus lateralis in line with their fibers down to, but not through, the periosteum. The lateral cortex of the proximal femur is exposed using two Hohmann retractors, one ventral and one dorsal. A submuscular, extraperiosteal tunnel is created with a tunneling instrument introduced through the proximal incision. The tip of this instrument should be kept in contact with the bone as a directional guide, until the distal end of the tunneling instrument is visible in the distal incision. It is important that the tunneling instrument is not passed back and forth repeatedly as this will result in damage and stripping of the periosteum (Fig 14-11).

a

b

c Fig 14-11a–c a

Fig 14-10 The selected plate is used as a template to mark the proximal and distal skin incisions while longitudinal traction is applied to the femur with the knee in 40º–60º flexion.

Tunneling instrument is used to prepare a submuscular, extraperiosteal tunnel for the plate. Avoid passing the instrument repeatedly back and forth as this will result in damage and stripping of the periosteum. b The proximal end of the selected plate is tied to the hole at the tip of the tunneling instrument by means of a suture. c The tunneling instrument is then withdrawn, pulling the attached plate along the submuscular tunnel that has been created.

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14

6

Femur, shaft

Operative procedure

(cont)

The proximal end of the selected plate is tied to the hole at the tip of the tunneling instrument by means of a suture. The tunneling instrument is then withdrawn, pulling the attached plate along the submuscular tunnel that has been created. The proximal end of the plate is positioned on the center of the lateral cortex of the proximal femur and fi xed in this position with a cortex screw inserted bicortically into the most proximal plate hole perpendicular to the lateral cortex. This screw is not fully tightened (Fig 14-12a). Longitudinal traction is applied to restore length and alignment to the femur (Fig 14-12b). The alignment is checked with the image intensifier. On the lateral view, the posterior cortices of the proximal and distal main fragments should be aligned. If this view is blocked by the plate, the distal end of the plate can be shifted temporarily anteriorly out of the way through the distal incision.

With the lateral cortex of the distal main fragment exposed with two Hohmann retractors, the distal end of the plate is centered on the lateral cortex and fi xed with a cortex screw inserted monocortically perpendicular to the cortical surface through the second last plate hole (Fig 14-12c). The proximal and distal screws are tightened. The fracture reduction is checked with the image intensifier. The length and rotational and axial alignment of the femur is then checked using the methods outlined in Chapter 10 (Complications and solutions). If reduction is satisfactory, the fi xation is completed using cortex screws introduced percutaneously through stab incisions and using the triple sleeve technique (Chapter 3 Instruments). At least three screws should be used bicortically to fi x each main fracture fragment proximally and distally.

c a Fig 14-12a–c

b

Indirect reduction of femoral fracture using a precontoured plate. a The proximal femur is exposed with two Hohmann retractors. The plate is passed into the prepared submuscular tunnel and fi xed preliminarily with a screw inserted into the most proximal plate hole perpendicular to the lateral femoral cortex. It is necessary to align the posterior border of the plate with the linea aspera. b Longitudinal traction is applied: the distal femur is exposed using two Hohmann retractors. c The plate is positioned in the center of the lateral cortex and fi xed with a perpendicular screw through the second last hole. 217

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7

Postoperative care

Pain control and thromboembolic prophylaxis follow standard guidelines. Early mobilization of the hip and knee joints is encouraged. Partial weight-bearing walking with crutches is started on the fi rst or second postoperative day. The amount of weight bearing permitted is gradually increased as fracture union progresses. 8

Pitfalls –

Fracture healing is monitored closely with regular x-rays. Bone grafting and/or implant revision may be indicated if no visible callus is demonstrated after 3 months.

9

Pearls +

Malalignment

Using the plate as a reduction tool

One of the commonest complications associated with the MIPO technique is rotational and axial malalignment which, if not detected and corrected, will lead to malunion of the fracture. Chapter 10 (Complications and solutions) outlines the various strategies to avoid this problem and the reader should refer to this chapter. If the initial proximal and distal screws are not inserted into the center of the lateral cortex of the femur or if their direction of insertion is not perpendicular to the cortical surface, malrotation and translation may occur at the fracture site (Fig 14-13a).

If the plate is to be used as a reduction tool, it is important to ensure that the proximal and distal main fracture fragments are correctly orientated in the neutral position. Pads should not be placed under the buttock as this will distort the rotation of the proximal fragment. Similarly, the distal fragment will be in the correct rotation if the knee is supported in flexion of 40–60º with the patella pointing upward. If the proximal and distal ends of the plate are then aligned to the center of the lateral cortex of the femur and the initial proximal and distal screws inserted perpendicular to the cortex, the resulting fracture alignment obtained will usually be satisfactory.

Maintaining the anterior bowing of the femur Fig 14-13a

If the plate is positioned such that its proximal and distal ends are too close to the posterior edge of the lateral cortex, the central segment of the plate may overlie the posterior margin of the lateral cortex rather than on the lateral surface itself so that screws inserted into this segment of the plate may actually miss engaging the bone. The reason for this is the anterior bowing of the femur (Fig 14-13b).

The anterior bowing of the femur can be restored with a padded support placed beneath the midshaft of the femur. A special sagittally bent LCP is available that can maintain the anterior bowing of the femur (see Fig 14-6b). If such a plate is not available, a broad straight plate can be adapted by contouring it to a convex shape and applying the contoured plate on to the anterolateral cortex of the femur and then inserting the screws obliquely (40º from the horizontal plane) in an anterolateral to posteromedial direction.

Fig 14-13b

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14

8

Femur, shaft

Pitfalls –

(cont)

9

Pearls +

(cont)

Sagittal plane angulation

Correcting shortening

Sagittal plane angulation may result if the femur is fi xed in a shortened position (Fig 14-14a).

To correct shortening, the following technique is useful. The fi rst screw inserted into the distal main fracture fragment should be through the second last hole in the distal end of the plate (Fig 14-14a). If subsequently, shortening is detected, as in the case of sagittal plane angulation, this screw is removed, longitudinal traction applied until the screw hole in the bone is aligned with the last plate hole, and the screw reinserted (Fig 14-14b). The length gained by this method depends on the distance between two plate holes which varies from the type of plate to be used (Fig 14-14c).

Fig 14-14a

Shortening can also be corrected using a push–pull screw technique or a distractor device. Fig 14-14b–c

b

c

Large intermediate fragments

a Fig 14-15a

In the presence of a large wedge fragment (Type 32-B fracture) that is widely separated, it may be advantageous to reduce this fragment. The aim of doing this is not to achieve an anatomical reduction, which would usually require considerable softtissue dissection or stripping, but rather to close the fracture gap so as to improve fracture healing (Fig 14-15a).

Realigning an intermediate fragment

b

The wedge fragment can be reduced using a percutaneous Schanz screw as a joystick and the reduction held by screw fi xation, or a standard cortex screw can be introduced through the appropriate plate hole to pull the wedge fragment toward the plate (Fig 14-15b).

Fig 14-15b

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10

Suggested reading

Höntzsch D (2001) Femur: shaft. Ruedi T, Murphy W, (eds) AO Principles of Fracture Management. Stuttgart New York: Georg Thieme Verlag, 460–468. Krettek C, Miclau T, Grün O, et al (1998) Intraoperative control of axes, rotation and length in femoral and tibial fractures. Technical note. Injury; 29 Suppl 3:29–39. Wenda K, Runkel M, Degreif J, et al (1997) Minimally invasive plate fi xation in femoral shaft fractures. Injury; 28 Suppl 1:13–19.

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Author

14.1 1

Suthorn BAVONRATANAVECH

Femur, shaft: wedge fracture, fragmented wedge—32-B3

Case description

a

2

Fig 14.1-1a–b A 35-year-old male, hit by a truck, sustained a closed fracture of the shaft of his left femur with an ipsilateral closed tibial fracture. His right lower leg was amputated with an open stump. He was conscious and in a stable condition to allow transfer to our hospital.

b

Indication for MIPO

As this case was the result of a high-energy injury, there was considerable soft-tissue damage in the left leg so that external fi xation of

3

Patient positioning

Patient lies supine with the hip and knee flexed to 60° and the patella in neutral position.

the tibial fracture was the treatment of choice even though it was a closed injury. This should be performed first. Patient was placed on a radiolucent operating table to facilitate stabilization of the femoral fracture using MIPO technique. The whole of the left lower extremity was prepared and draped to save time. In this case, there was no need for early weight bearing as the right leg had been amputated, and it would take at least 2 months before a prosthesis could be fi tted.

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14

4

Femur, shaft

Surgical approach

a

b

c

Fig 14.1-2a–c a–b

5

A proximal incision of about 5 cm is made according to the preoperative plan. The vastus lateralis is elevated. The distal incision follows manual distraction. The plate is used as a tunneler. It is slipped under the muscle, passing the fracture to the distal fragment.

c

A precontoured broad plate (16-hole DCP) is slipped under muscle from proximal incision. The position of the plate is checked to ensure that it is lying on the lateral aspect of femur.

Reduction

a

b

c

Fig 14.1-3a–c a

Following proximal screw fi xation, manual traction is applied and the distal fragment is temporarily fi xed using the second distal hole.

b

c

An isolated screw is fi xed as an anchorage beyond distal end of plate to allow distraction by a bone spreader so as to gain length if necessary. Anchorage screw fi xation 2 cm from the plate end.

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14.1

6

Femur, shaft: wedge fracture, fragmented wedge—32-B3

Fixation

a

b

c

Fig 14.1-4a–c a

Percutaneous fi xation with additional screws. Stab incision and blunt dissection of muscle to reach the plate hole. Triple sleeve is inserted for screw application. (The technique for screw fi xation is described in Chapter 3 Instruments.)

a

b c

Skin incisions in MIPO technique. Skin suturing.

b

Fig 14.1-5a–b a

Postoperative x-rays of the ipsilateral multifragmentary tibial fracture treated with external fi xator. Plating of the fibular fracture was carried out fi rst. b Immediate postoperative x-ray of femur shows comminution without any alignment of wedge fragment. 223

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14

7

Femur, shaft

Rehabilitation

Fig 14.1-6a–b a

a

a

X-rays 3 months postoperatively. Patient only mobilized on wheel chair as prosthesis for the amputated right leg was not ready. The external fi xator was used for defi nitive treatment of the left tibial fracture. It will be removed when the fracture has healed. b X-ray 3 months postoperatively of the left femur shows callus formation.

b

b

c

a

b

Fig 14.1-7a–c

Fig 14.1-8a–b

a

a

X-rays of the left femur 6 months after surgery show bony consolidation. b–c X-rays of left tibia 6 months postoperatively show healing with proper alignment.

Full flexion of left knee 3 months after surgery. b Patient walking full weight bearing on left leg with prosthesis on right leg.

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Authors

14.2 1

Theerachai APIVATTHAKAKUL, Suthorn BAVONRATANAVECH

Femur, shaft: wedge fracture, spiral wedge—32-B1

Case description

Fig 14.2-1a–b

a

2

b

Indication for MIPO

Treatment by relative stability with indirect reduction is suitable for this fracture. Fixation may be achieved either by intramedullary

A 25-year-old male met with a motorcycle accident and sustained an isolated closed fracture of the distal third of his left femur. The fracture extended from midshaft to distal third with a spiral wedge. The patient underwent emergency laparotomy for abdominal pain and distension shortly after admission.

3

Positioning

Patient lies on a radiolucent operating table with the knee flexed on a supporting pad.

nailing or MIPO. Intramedullary nailing would necessitate transfer of patient to a fracture table.

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14

4

Femur, shaft

Surgical approach

a

b

c

d

Fig 14.2-2a–d a

As the plate will extend to the distal femoral metaphysis, it has to be contoured and adapted to the lateral aspect of the distal femur. A condylar plate can be used as a template for the distal femur. The plate is used to locate the sites for the incisions in the proximal and distal femur. b Following skin incision, tensor fasciae latae is split and vastus lateralis elevated, avoiding periosteal stripping. c Submuscular insertion of tunneler from proximal to distal incision. d Insertion of contoured plate along the tunnel.

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14.2

5

Femur, shaft: wedge fracture, spiral wedge—32-B1

Reduction

a

b

c

Fig 14.2-3a–c a

A broad 18-hole DCP is inserted and screw fi xation is performed according to the preoperative plan. b–c In the proximal fragment, the screws are inserted along the midlateral line of the femur. It is important to place the screws perpendicular to shaft axis.

Fig 14.2-4a–b a

a

b

Proper alignment of plate is checked distally as well as the distance between plate end and upper pole of patella. b Following manual traction, the distal fragment is provisionally stabilized by monocortical screw fi xation and alignment is checked before defi nitive bicortical fi xation.

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14

6

Femur, shaft

Fixation

a

b

c

Fig 14.2-5a–c a b c

Image intensifier is positioned for lateral view to check axis. Internal and external hip rotation is measured with the knee flexed and compared with preoperative measurements of contralateral side. Length is measured using cautery cable and compared with preoperative recordings of intact side.

Fig 14.2-6

a

b

Percutaneous screw fi xation using sleeve for guidance.

c

Fig 14.2-7a–c Screw fi xation of middle fragment under fluoroscopic guidance.

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14.2

7

Femur, shaft: wedge fracture, spiral wedge—32-B1

Rehabilitation

a

b

Fig 14.2-8a–b X-rays, AP and lateral view after 2 months show callus formation.

a

a

b

Fig 14.2-9a–b X-rays, AP and lateral view after 4 months with increased bridging callus.

b

Fig 14.2-10a–b

Close-up x-rays show good consolidation of fracture site.

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15

Femur, distal

1

Introduction

231

Cases

1.1 1.2

Classification

231

15.1

Indications and contraindications for MIPO

232

2

Surgical anatomy

232

3

Preoperative assessment and timing for surgery

233

4

Preoperative planning

234

5

OR set-up

235

5.1

Anesthesia

235

5.2

Patient positioning and image intensifier

235

5.3

Implants and instruments

235

6

Operative procedure

236

6.1

Surgical approach

236

Femur, distal: partial articular fracture of the medial condyle—33-B2 and spiral wedge shaft fracture—32-B1

15.2

Femur, distal: extraarticular fracture, simple—33-A1 and simple spiral shaft fracture—32-A1

15.3

247

Femur, distal: extraarticular fracture, simple 33-A1

251

Teaching video on DVD-ROM 15

6.1.1

243

Femur, distal—lateral parapatellar approach

Modified standard lateral approach

6.1.2 Lateral or medial parapatellar approach 6.2

Reduction and fixation of the articular

6.3

Reduction of the metaphyseal/diaphyseal

fractures fracture component 6.4

238 238

Fixation of the metaphyseal/diaphyseal fracture component

238

7

Postoperative care

240

8

Pitfalls

240

9

Pearls

240

10

Suggested reading

242

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Author

15

1

Suthorn BAVONRATANAVECH

Femur, distal

Introduction

The majority of distal femoral fractures require surgical stabilization as the results of conservative treatment of these injuries, with the exception of that of undisplaced fractures, are frequently unsatisfactory. Although the introduction of various implant systems, including the 95° condylar plate, the dynamic condylar screw (DCS), and the retrograde femoral nail, has led to improvements in treatment outcomes, problems persist. Complications such as delayed union, nonunion, malunion, knee stiffness, and infections are still encountered. Most of the difficulties in treating distal femoral fractures can be attributed to the fact that these fractures frequently occur in young individuals as a result of high-energy trauma, or in elderly patients with osteoporosis. The former are often associated with severe soft-tissue injuries and fragmentation of both the intraarticular and metaphyseal components of the fracture, while the latter present problems of implant loosening and loss of fi xation. With the introduction of indirect fracture reduction, bridge plating principles, minimally invasive plating techniques, and locking compression plates (LCP), some of the difficulties associated with the treatment of these fractures have been resolved, but problems remain as these methods are technically demanding and there is a significant learning curve. 1.1

a

b

c

Fig 15-1a–c

33-A extraarticular fracture. 33-A1 simple b 33-A2 metaphyseal wedge and/or fragmented wedge c 33-A3 metaphyseal complex a

a

b

c

Fig 15-2a–c

33-B partial articular fracture. a 33-B1 lateral condyle, sagittal b 33-B2 medial condyle, sagittal c 33-B3 frontal

Classification

The Müller AO Classification is used for classification of fractures of the distal femur. The distal femur is designated by the number 33. Type 33-A are extraarticular fractures, type 33-B partial articular fractures and type 33-C complete articular fractures (Fig 15-1, Fig 15-2, Fig 15-3).

a

b

c

Fig 15-3a–c

33-C complete articular fracture. 33-C1 articular simple, metaphyseal simple b 33-C2 articular simple, metaphyseal multifragmentary c 33-C3 articular multifragmentary a

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1 1.2

Introduction

(cont)

Indications and contraindications for MIPO

The advantages of indirect fracture reduction and submuscular plating in the treatment of fractures of the distal femur lie in the fact that the soft-tissue envelope surrounding the fracture remains largely intact, thus preserving the biology and enhancing the chances of fracture union, reducing the need for bone grafting as well as the incidence of infection. While this applies to the metaphyseal/diaphyseal component of the fracture, which generally requires restoration of length, rotation, and axial alignment, the articular component of the fracture often requires open, anatomical reduction. Also, while relative stability is adequate for the metaphyseal/diaphyseal region, compression with lag screw fi xation is required for the articular fractures.

In type 33-B fractures with partial articular involvement, MIPO does not confer any particular advantages unless there is an associated femoral shaft fracture. In isolated type 33-B fractures, the treatment of choice is open reduction of the articular fragment followed by interfragmentary compression using lag screws, supplemented if necessary by an additional buttress plate. MIPO becomes increasingly more difficult if the fracture is more than 2 weeks old. This is because indirect fracture reduction becomes problematic due to scarring and soft-tissue contractures. MIPO should not be attempted in the presence of severe wound contamination or infection. It is also contraindicated if there is an associated vascular injury.

MIPO is particularly suitable for type 33-A2 and 33-A3 and type 33-C fractures.

2

Surgical anatomy

The distal femur has a unique anatomical shape (Fig 15-4). Seen from an end-on view, the lateral surface has a 10° inclination from the vertical while the medial surface has a 20–25° slope. A line drawn from the anterior aspect of the lateral femoral condyle to the anterior aspect of the medial femoral condyle (patellofemoral inclination) slopes approximately 10°. These anatomical details are important when inserting screws or blade plates. In order to avoid joint penetration, these should be placed parallel to the patellofemoral and femorotibial joints. Also, when positioning a plate on the lateral aspect of the distal femur, if the plate does not lie flat against the lateral femoral condyle before screw insertion, there will be a risk of rotational malalignment of the distal articular block when screw fi xation is completed. Placing a plate too far posteriorly on the lateral femoral condylar surface risks screw or blade penetration into the intercondylar notch and can also result in

a

b

c

Fig 15-4a–c

Anatomy of the left distal femur. AP view of the distal femur. b Articular view with the knee in flexed position shows that the lateral surface slopes about 10° from the vertical, while the medial surface slopes about 25°. A line joining the anterior aspect of the lateral femoral condyle to the medial femoral condyle slopes about 10°. c Lateral view of femoral shaft in relation to condyles. a

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15

2

Femur, distal

Surgical anatomy

(cont)

medial displacement of the articular block as well as internal rotational deformity when the articular block is later fi xed on to the shaft fragment. The muscle attachments to the distal femur are responsible for the typical displacement of the distal articular block following a fracture, namely shortening with varus and extension deformity. Shortening is due to the pull of the quadriceps and hamstring muscles while the varus and extension deformity is

3

caused by the unopposed pull of the adductors and gastrocnemius, respectively. The popliteal vessels and the tibial and common peroneal nerves lie in close proximity to the posterior aspect of the distal femur. Because of this, vascular injuries occur in about 3% and nerve injuries in about 1% of fractures of the distal femur.

Preoperative assessment and timing for surgery

Clinical and radiological assessment should be carried out preoperatively. In the case of young patients with high-energy injuries, clinical assessment should include the hemodynamic status, associated injuries, status of the soft tissue, and the neurovascular status of the injured limb. In the case of elderly patients with low-energy fractures, the hemodynamic and cardiovascular status, bone quality, and other comorbidities should be assessed. Radiological assessment should include AP and lateral x-rays of the femur and knee. Traction fi lms are sometimes required to provide more information on the fracture morphology. Oblique views of the knee provide additional details in the case of intraarticular involvement. CT scans with 3-D reconstructions are helpful in multifragmentary intraarticular fractures.

Angiography is indicated if vascular injury is suspected. The timing of surgery depends on the patient’s general condition, the presence of associated injuries, the state of the soft tissue, and the experience of the surgical team. Open fractures with significant contamination should be treated by emergency wound debridement followed by temporary stabilization with a knee-bridging external fi xator. In the case of intraarticular involvement, the articular component may be reconstructed during the initial surgical intervention using lag screws. Care should be taken that the position of these lag screws would not interfere with the subsequent placement of the defi nitive implant. MIPO may be carried out as a defi nitive procedure once the wound has healed. Closed fractures may be stabilized as an elective procedure as soon as feasible. In the presence of severe soft-tissue swelling, surgery should be delayed till the swelling has subsided.

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4

Preoperative planning

The following factors should be included in the preoperative plan (Fig 15-5): Assessment of the contralateral uninjured limb. This includes determination of its length and rotational profi le. The anatomical axis of the uninjured femur should be measured by drawing a line through the center of the femoral shaft and a line parallel to its distal articular surface. In males, there is normally 6°–7° of distal articular surface valgus while in females, this angle averages 8°–9°. Elderly patients may have some degree of osteoarthritis with varus deformity in the knees and this should be taken into consideration in the preoperative plan.

a

Preparing a graphic preoperative plan with the fracture fragments drawn-in and reduced. With the help of templates, the appropriate implant for fracture fi xation is selected, including its length and position on the distal femur, the number and type of screws, and their order of insertion. The strategy for dealing with the intraarticular fractures, if present. The method of fracture reduction. The surgical approach.

b

c

d

Fig 15-5a–d a

The fi rst step is to restore the articular surface by anatomical reduction of the fracture fragments and preliminary fi xation with K-wires. Two cancellous bone screws are used for fracture fi xation. The position of these screws should not interfere with the subsequent placement of the 95° condylar plate.

b

The template of a condylar plate is placed over the drawing to select the appropriate length of blade and side plate. The indirect reduction technique will minimize damage to the vascularity of the fracture zone. c–d Correct placement of the fi xed angled device will help to reduce the fracture in proper alignment and correct mechanical axis.

234

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15

Femur, distal

5

OR set-up

5.1

Anesthesia

General or regional anesthesia may be used, the choice depending on the general condition of the patient and on the opinion of the anesthetist. An epidural catheter may be inserted for postoperative pain control. 5.2

Patient positioning and image intensifier

The operation is carried out with the patient lying supine on a radiolucent operating table. Padding is positioned to support the knee of the injured side in about 60°–70° flexion with the patella pointing anteriorly in neutral position (Fig 15-6). Sterile preparation and draping should allow exposure and free movements of the hip and knee of the injured side. The contralateral uninjured limb may also be prepared and draped so that it is available for comparison with the injured side during the course of the surgery. A sterile metallic marker tape, if available, may be used for length measurement during surgery. The image intensifier is positioned on the side of the operating table opposite to that of the injured limb. 5.3

Implants and instruments

The implants suitable for MIPO of distal femoral fractures include: Fixed angled devices such as the 95° condylar plate and the DCS. Anatomical plate with standard cortex screw constructs such as the condylar buttress plate. Locking implants such as the LISS for distal femur (LISS DF) or the distal femur LCP. Fixed angled devices, by virtue of the fi xed angle between the blade or the screw and the side plate, help to protect against varus collapse of the reduced articular block. Proper place-

Fig 15-6

Patient lies in a supine position with the knee supported in 70° flexion.

ment of the blade or screw parallel to the patellofemoral and femorotibial joint surfaces will aid in the reestablishment of the normal frontal and sagittal plane alignment of the distal femur. Thus these implants can function both as reduction aids as well as fi xation tools. The 95° condylar plate is more difficult to use as its insertion must be controlled in three planes at the same time. Difficulty may also be encountered during insertion of the blade into the prepared canal in the femoral condyles. The DCS, on the other hand, is technically easier to use as only two planes are required in the insertion of the screw – the sagittal alignment of the side plate can be adjusted by rotating the plate–screw construct after insertion. However, the DCS requires significant bone removal for its insertion; additionally, these fi xed angled devices are not suitable for use in complex intraarticular fractures as their fi xed angle may interfere with or disrupt the fi xation of the articular block. The condylar buttress plate may be used for type 33-C2 or 33-C3 fractures. However, because standard screws are used with this plate, there is no angular stability between the screws and the plate. This increases the risk of screw toggling and 235

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5

OR set-up

(cont)

loosening, leading to varus malalignment of the fracture, especially in the absence of a medial cortical buttress. This risk is increased in elderly patients with osteoporotic bone. The LISS DF is an implant that was specifically designed for minimally invasive application for fractures of the distal femur. It consists of a plate-like device and locking head screws (LHS) which together act as an internal fi xator. Its characteristics include multiple fi xed angled screws which lock into the distal end of the fi xator and an insertion handle that serves as a guide for the submuscular introduction of the fi xator as well as for percutaneous insertion of self-drilling, self-tapping LHS for the fi xation of the diaphyseal component of the fracture.

6 6.1

Because only LHS are used, fracture reduction must be achieved before screw insertion as the LHS cannot be used as reduction aids, although minor degrees of varus-valgus malalignment can be corrected with a special pulling device. The angular stability provided by this internal fi xator system makes it more suitable for use in osteoporotic bone. The distal femur LCP is similar in concept to the LISS DF but has the advantage of having combination holes in the plate so that it can be used with either standard screws or LHS. The cortex screws can be used to pull the bone toward the anatomically shaped plate, thus permitting some degree of indirect fracture reduction.

Operative procedure Surgical approach

The surgical approach used depends on whether the fracture is extraarticular or intraarticular. For extraarticular fractures, a modified standard lateral approach is used. For intraarticular fractures, a lateral or medial parapatellar approach is used. 6.1.1

Modified standard lateral approach

In the modified standard lateral approach (Fig 15-7), the skin incision starts from Gerdy’s tubercle and extends proximally for about 6–8 cm. The iliotibial tract is split along the direction of its fibers. The space between the vastus lateralis and the periosteum is opened and a submuscular tunnel created. Then the implant is slipped into this submuscular tunnel. The joint capsule may be opened in line with the split in the iliotibial tract. Although opening of the joint capsule is not necessary in extraarticular fractures, the advantage is that it can help in the correct placement of the implant on the lateral surface of the lateral femoral condyle by direct visualization. The screws are inserted through multiple stab incisions.

Fig 15-7 For type 33-A fractures, the modified standard lateral approach is adequate. The incision is made at the distal part of femur to expose only part of condyle and joint level. A separate proximal incision is made over the proximal end of the plate.

236

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15

6 6.1.2

Femur, distal

Operative procedure

(cont)

Lateral or medial parapatellar approach

The lateral or medial parapatellar approach (Fig 15-8a–d) is used for intraarticular fractures as excellent exposure of the distal femoral articular surface is possible. The lateral approach is more commonly utilized, but if the major comminution is in the medial femoral condyle, the medial parapatellar approach is used instead. A straight skin incision approximately 1 cm lateral to the patella is made. Dissection is carried down to the extensor retinaculum. A lateral or medial parapatellar curvilinear retinacular incision is then made to enter the knee joint. In the lateral parapatellar approach, the lateral retinacular incision can be extended proximally between the rectus femoris and vastus lateralis. In the medial parapatellar approach, the medial retinacular incision may be extended proximally along the medial one third of the quadriceps tendon. A cuff of tissue is left attached to the side of the patella to facilitate later repair.

b

a

Eversion of the patella and flexing the knee exposes the distal articular surface of the femur enabling reduction and fi xation of the articular fractures to be carried out. When this is completed, the patella is repositioned. Next, the implant is slipped into a submuscular tunnel along the lateral cortex of the femur, following which the screws are inserted to complete the fi xation. Whatever the distal incision used, it is prudent to make another incision that corresponds to the position of the proximal end of the plate. The lateral cortex of the femoral shaft is exposed through this incision using two Hohmann retractors. The purpose of this incision is to ensure that the proximal end of the plate is lying against the center of the lateral cortex of the femoral shaft. This helps to ensure proper alignment of the fracture following plate fi xation.

c

d

Fig 15-8a–d a–b Lateral skin incision and lateral parapatellar exposure in

c–d Lateral skin incision and medial parapatellar exposure in

type 33-C fractures. Flexion of knee will give a complete exposure of the articular fracture.

type 33-C fractures in case of coronal fractures of the medial condyle. This approach is indicated when the major comminution involves the medial femoral condyle. 237

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6 6.2

Operative procedure

(cont)

Reduction and fixation of the articular fractures

In type 33-C fractures, the next step consists of anatomical reduction and internal fi xation of the articular fractures. Various aids can be used to obtain the reduction of the articular fracture fragments: Schanz screws can be inserted into the medial and lateral femoral condyles to serve as joysticks to secure fracture reduction. These are particularly useful in types 33-C1 and 33-C2 fractures. Large pointed reduction forceps or pelvic reduction clamps are useful for holding the medial and lateral femoral condyles together after they have been reduced. K-wires are also useful for temporary fi xation of the reduced condylar fragments. Following reduction of the articular fractures, lag screw fi xation is carried out; preferably with small fragment 3.5 mm cortex screws or 4.0 mm partially threaded cancellous bone screws. The lag screws are introduced in a lateral to medial direction in the case of intercondylar fractures, and in an anterior to posterior direction in the case of frontal plane “Hoffa” fractures. The position of these lag screws should be planned so that they do not interfere with the subsequent placement of the defi nitive implant for the fi xation of the supracondylar component of the fracture. 6.3

Reduction of the metaphyseal/diaphyseal fracture component

The next step consists of the reduction of the articular block to the distal femoral metaphysis/diaphysis. This is especially important if the LISS DF is to be used as the defi nitive fi xation device. In the case of fi xed angled devices, such as the DCS or 95° condylar plate, or the distal femur LCP, the device itself can be used as a reduction aid as the standard screws can be used to draw the bone to the plate and so help to reestablish the

normal frontal, axial, and sagittal alignment of the distal femur. Closed indirect reduction should be the goal. A variety of reduction aids may be used: Pads placed posterior to the supracondylar region of the distal femur to keep the knee flexed at about 60°–70° will help to relax the gastrocnemius and correct the frequent hyperextension deformity of the articular block. Manual traction applied to the ankle with a force vector that is directed posteriorly utilizing the supracondylar pad as a fulcrum will help to reduce the fracture and restore limb length and rotational and axial alignment. A Schanz screw inserted from an anterior to posterior direction into the articular block just proximal to the articular margin can be used as a joystick to derotate the frequently hyperextended distal fragment into proper alignment with the proximal fracture fragment. The femoral distractor or external fi xator can be used to obtain and maintain fracture reduction. 6.4

Fixation of the metaphyseal/diaphyseal fracture component

The LISS DF or distal femur LCP are locking implants that provide angular stability and so should be the implants of choice. If these are not available, conventional fi xed angled implants, such as the DCS or the 95° condylar plate, can also be used. The main difference in the application of the LISS DF and that of the fi xed angled implants is that in the case of the LISS DF, reduction of the supracondylar component of the fracture should be carried out before application of the fi xator. In the case of the fi xed angled implants, the DCS or the blade of the 95° condylar plate should be inserted into the articular block before reduction of the metaphyseal/diaphyseal component of the fracture as it is frequently necessary to manipulate the articular block into a valgus position in order to allow the barrel of the side plate to align with the end of the DCS, or to

238

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15

6

Femur, distal

Operative procedure

(cont)

allow the blade of the 95° condylar plate to align with the canal which has been chiseled in the articular block before these can be inserted. The main steps in the application of the LISS DF are as follows: The insertion handle is assembled on to the selected LISS DF. The LISS DF is then inserted through the distal incision and slid proximally into the submuscular tunnel between the vastus lateralis and periosteum of the lateral femoral cortex until the proximal end of the fi xator appears in the proximal incision lying on the midlateral aspect of the femoral shaft. The distal end of the fi xator must lie flat up against the lateral surface of the lateral femoral condyle to ensure an optimal fit. K-wires are inserted into distal and proximal ends of the LISS DF through the insertion guide for temporary fi xation. The position of the LISS DF in relation to the femur as well as the length and rotation profi le of the reduced injured limb is checked by the image intensifier and clinical means. If the reduction of the fracture and the position of the LISS DF are satisfactory, the LHS can be inserted percutaneously with the help of the insertion handle. The screws should be inserted close to and remote from the fracture gap in the main fracture fragments. At least four screws should be used on each side of the fracture. More screws inserted bicortically are required in the presence of osteoporosis. Following completion of screw insertion, a fi nal check of the fracture reduction and fi xation is made. The main steps in the application of the DCS by the MIPO technique are as follows: A guide wire is inserted into the articular block under fluoroscopic guidance parallel to the patellofemoral and femorotibial joint surfaces 2 cm proximal to the distal femoral articular surface. The entry point should be located

at the junction of the anterior and middle thirds of the lateral surface of the lateral femoral condyle in line with the midlateral line of the lateral cortex of the shaft of the femur. The length of the guide wire within the articular block is measured and the triple reamer adjusted accordingly. Drilling, followed by tapping if necessary, is next carried out. The selected condylar screw is connected with the insertion handle, then passed over the guide wire and inserted into the articular block. The side plate, with the barrel pointing laterally, is then slid proximally deep to the vastus lateralis along the linea aspera of the femur. The side plate is then rotated 180° so that the barrel is pointing medially. The barrel is then slipped on to the condylar screw. To facilitate this, it is frequently necessary to manipulate the articular block into a valgus position. Fracture reduction is then carried out. If fracture reduction and implant position are satisfactory, a cortex screw is inserted into the second last hole proximally. The limb length, axes, and rotation are checked by clinical and radiological means. If satisfactory, the remaining screws are inserted into the proximal fracture fragment through percutaneous and transmuscular stab wounds. The screws are placed divergently so as to increase pullout strength and decrease the length of the incisions needed for insertion. At least one additional cancellous bone screw should be inserted into the articular block to improve the stability of the construct. A fi nal check of the fracture reduction and fi xation is then made. In the case of the 95°condylar plate, after chiseling the canal in the distal articular block and submuscular insertion of the 239

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6

Operative procedure

(cont)

side plate, insertion of a Schanz screw as a joystick in the distal fragment to align the canal to the blade will facilitate blade insertion. The directional guide pin that was inserted into the articular block parallel to the patellofemoral and femorotibial joint surfaces should be left in place to serve as a guide to the 7

Postoperative care

A continuous passive motion (CPM) machine may be applied postoperatively to mobilize the knee until the patient can actively flex and extend the knee without any assistance. Nonweight-bearing walking with crutches is begun early, followed 8

direction of the canal so as to facilitate the introduction of the blade. Using a plate with a short blade is another method of facilitating blade insertion. Fracture reduction is completed by manual traction to align the side plate along the femoral shaft.

Pitfalls –

by partial weight-bearing walking within the fi rst 2 months, with progression to full weight bearing when x-rays show fracture union.

9

Pearls +

Pitfall 1

Pearl 1

Irrespective of the type of fi xation device used, it is important to ensure that the implants inserted into the distal articular block are parallel to the patellofemoral and femorotibial joint surfaces in order to avoid joint penetration and malpositioning of the fracture, resulting in axial or rotational malalignment (Fig 15-9).

In osteoporotic bone, more screws should be used in the construct to improve the stability of the fi xation. When LHS are used with the LISS DF or distal femoral LCP, bicortical instead of monocortical screw fi xation is recommended to increase the pullout strength.

a

b

c

Fig 15-9a–c Complications following malpositioning of a blade plate: a Axial deviation leading to a valgus deformity b Perforation of posterior cortex and joint penetration c Axial deviation leading to a varus deformity

240

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15

8

Femur, distal

Pitfalls –

(cont)

9

Pearls +

(cont)

Pitfall 2

Pearl 2

The fi xation device should be positioned on the lateral surface of the lateral femoral condyle at the junction of its anterior and middle thirds in alignment with the shaft of the femur, again to avoid malalignment of the fracture following fi xation of the proximal part of the device to the shaft fragment.

Hyperextension of the distal articular block due to the pull of the gastrocnemius is common. This must be corrected by appropriate padding in the supracondylar region, supplemented, if necessary, by manipulation with the help of anteroposterior Schanz screws as joysticks.

Pitfall 3

Pearl 3

When using the LISS DF, it is important to ensure that the proximal end of the fi xator is centered on the lateral cortex of the femoral shaft. This is because the LHS must be inserted perpendicular to the surface of the fi xator and if the fi xator is off-center or not sitting flat on the lateral cortex, the screws may not obtain adequate purchase on the bony cortex and this in turn may lead to screw cutout. In the case of conventional plates or the distal femur LCP, this malpositioning of the proximal end of the plate is not as critical since some adjustments can be made by directing the drill obliquely in order to engage both cortices.

When using a distal femur LCP, the posterior border of the plate should lie parallel with the posterior cortex of distal femur. This position prevents flexion or extension deformity of the femoral condyles.

241

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10

Suggested reading

Bolhofner BR, Carmen B, Clifford P (1996) The results of open reduction and internal fi xation of distal femur fractures using a biologic (indirect) reduction technique. J Orthop Trauma; 10(6):372–377. Kregor PJ, Stannard J, Zlowodzki M, et al (2001) Distal femoral fracture fi xation utilizing the Less Invasive Stabilization System (L.I.S.S.): the technique and early results. Injury; 32 Suppl 3:32–47. Krettek C, Schandelmaier P, Miclau T, et al (1997) Minimally invasive percutaneous plate osteosynthesis (MIPPO) using the DCS in proximal and distal femoral fractures. Injury; 28 Suppl 1:20–30. Krettek C, Müller M, Miclau T (2001) Evolution of minimally invasive plate osteosynthesis (MIPO) in the femur. Injury; 32 Suppl 3:14–23. Mast J, Jakob R, Ganz R (1989) Planning and Reduction Technique In Fracture Surgery, 1st ed. Berlin Heidelberg New York: Springer-Verlag. Mize RD, Bucholz RW, Grogan DP (1982) Surgical treatment of displaced, comminuted fractures of the distal end of the femur. J Bone Joint Surg [Am]; 64(6):871–879. Rosenkranz J, Babst R (2006) [A special instrument: the LISS tractor.] Oper Orthop Traumatol; 18(1):88–99. German. Rüedi TP, Murphy WM (2001) AO Principles of Fracture Management. Stuttgart New York: Georg Thieme Verlag. Stover M (2001) Distal femoral fractures: current treatment, results and problems. Injury; 32 Suppl 3:3–13.

242

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Author

15.1 1

Suthorn BAVONRATANAVECH

Femur, distal: partial articular fracture of the medial condyle—33-B2 and spiral wedge shaft fracture—32-B1

Case description

a

2

b

Indication for MIPO

In this fracture type, a condylar plate or a DCS with a long side plate is recommended so that fi xation of both fractures can be achieved with a single implant. Instead of conventional plate application, which often involves extensive dissection of soft tissue, MIPO tech-

Fig 15.1-1a–c A 30-year-old male motorcyclist sustained a right femoral shaft fracture with a spiral wedge and an additional coronal fracture of the medial femoral condyle. No associated injury.

c

3

Positioning

Patient is in supine position on a radiolucent operating table with a supporting pad beneath the knee to keep it in 70° flexion. The image intensifier is positioned on the opposite side of the operated limb.

nique is favored as it tends to minimize the damage to the soft tissue and blood supply.

243

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15

4

Femur, distal

Surgical approach

a

b

Fig 15.1-2a–b a

surface of the distal femur. In this case, a medial parapatellar approach is preferred over a lateral parapatellar approach, as the former gives better exposure of the medial femoral condyle where the coronal fracture is located.

Skin incision is made about one fi nger’s breadth from the lateral margin of patella. b Subcutaneous tissue is undermined medially; a medial parapatellar arthrotomy is made and the patella everted laterally with the knee flexed to 90º, exposing the articular

5

Reduction

a

b

c

Fig 15.1-3a–c a

Medial condyle fracture is reduced and held temporarily in position by a K-wire followed by fi xation using a malleolar screw. A 4-hole one-third tubular plate is applied for additional stability and to prevent displacement during hammering of the chisel to create the canal for insertion of the blade of the condylar plate.

b c

Condylar plate application is performed according to standard AO technique to ensure correct placement. Submuscular tunnel is prepared using a tunneler from distal to proximal.

244

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15.1

5

Femur, distal: partial articular fracture of the medial condyle—33-B2, and spiral wedge shaft fracture—32-B1

Reduction

(cont)

a

b

c

Fig 15.1-4a–c a b

c

6

Condylar plate is inserted with the blade pointing laterally. Plate is rotated 180º to allow for blade insertion into the prepared canal. A Schanz screw is used to manipulate the distal femoral articular block so as to align the canal to the blade to facilitate its insertion. Skin incisions before suturing.

Fixation

If the blade is inserted in the correct orientation with respect to the patellofemoral and tibiofemoral joint surfaces, the side plate should align itself to the femoral shaft.

a

b

c

Fig 15.1-5a–c

After manual traction with the knee in flexion, a cortex screw is inserted monocortically in the second last hole proximally. Length and alignment are checked before fi nal fi xation. 245

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15

7

Femur, distal

Rehabilitation

a

b

a

b

Fig 15.1-6a–b

X-rays 3 months after fi xation show good callus formation.

Fig 15.1-7a–b

Range of motion of right knee 3 months after surgery.

246

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Author

15.2 1

Suthorn BAVONRATANAVECH

Femur, distal: extraarticular fracture, simple—33-A1 and simple spiral shaft fracture—32-A1

Case description

Fig 15.2-1a–c

a

2

b

Indication for MIPO

In this case, an LCP distal femur (with combination holes) using locking head screws (LHS) is selected in order to improve stability of

A 70-year-old fe-male sustained a closed spiral fracture of right femur extending from the distal third to the supracondylar area. Some degree of osteoporosis and degenerative arthritis of the knees with genu varum are visible.

c

3

Patient positioning

Patient lies in supine position on a radiolucent operating table with a supporting pad to keep knee in 60° flexion.

fi xation, and applied using MIPO technique to minimize soft-tissue damage. The advantage of this plate is that it can be used for indirect reduction. The aim in this case is to obtain stable reduction with valgus alignment.

247

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15

4

Femur, distal

Surgical approach

a

b

Fig 15.2-2a–b

A curved incision of about 7 cm is made along the lateral aspect of distal femur. The tensor fasciae latae is split and the vastus lateralis is elevated. Horizontal joint axis is marked by a K-wire, the posterior cortex of distal femur being oriented horizontally. 5

Reduction

a

b

Fig 15.2-3a–b a

In order to facilitate surgical technique, the spiral fracture is fi rst reduced by passing a cerclage wire for preliminary stabilization prior to screw and plate fi xation. A single lag screw is inserted to secure the spiral fracture. The cerclage wire is left in place.

b

A tunneler is used to prepare a submuscular extraperiosteal tunnel according to plate length.

248

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15.2

6

a

Femur, distal: extraarticular fracture, simple—33-A1 and simple spiral shaft fracture—32-A1

Fixation

b

Fig 15.2-4a–c a

c

LCP distal femur is inserted with handle, and a K-wire is drilled through a hole in the guiding block for temporary fi xation. The image intensifier is used to check proper plate location, followed by insertion of LHS in condylar area. b It is important to align the posterior border of the plate parallel with the posterior cortex of the femur. c Applying manual traction with the knee flexed, fracture reduction and temporary fi xation of the plate to the proximal fragment is carried out using a cortex screw inserted monocortically. It is important to ensure that the plate is aligned with the center of the bone. Fracture alignment and plate position are checked. LHS are inserted through remaining plate holes; the cortex screw may be replaced by an LHS. Cerclage wire may be removed but in this case, it has been left in situ. i

249

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15

7

a

Femur, distal

Rehabilitation

b

a

Fig 15.2-5a–b Postoperative x-rays show fracture fi xation with distal femur LCP. Patient started physiotherapy 3 days after removal of drainage.

b

Fig 15.2-6a–b

X-rays 4 months postoperatively show healing with callus formation.

Fig 15.2-7 Patient walks with partial weight bearing, regaining 90° knee flexion, 1 month postoperatively.

250

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Author

15.3 1

Frankie KL LEUNG

Femur, distal: extraarticular fracture, simple 33-A1

Case description

a

2

b

Indication for MIPO

Fig 15.3-1a–b A 74-year-old female fell down a staircase and sustained an injury to the right thigh. X-rays showed marked osteoporosis and an extraarticular distal femoral fracture. As the fracture was very unstable, operative treatment was selected as conservative treatment with a cast would not be able to immobilize the fracture adequately.

3

Patient positioning

Conventional compression plating is not suitable as it requires extensive surgical dissection: devascularization impairs healing and decrease of compression may result before adequate callus formation. Further, adequate fi xation may be problematic in osteoporotic bone. Insertion of a LISS DF as a bridging internal fi xator is the treatment of choice. Use of locking head screws (LHS) reduces the probability of loosening and improves stability. Because of minimal stripping of the surrounding soft tissue, rapid callus formation and fracture healing are to be expected. The use of a distal femoral nail (DFN) would be an acceptable alternative.

Fig 15.3-2

After successful spinal anesthesia, the patient is placed on a traction table to reduce and maintain the fracture. The other alternative is to use external fi xator on normal operating table with a supporting pad placed under the knee to facilitate fracture reduction.

251

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15

4

Femur, distal

Reduction

Fig 15.3-3

Correct reduction should be realized before implant insertion.

5

Fixation

Fig 15.3-4 A 6–7 cm incision is made. Dissection is performed to expose lateral femoral condyle.

Fig 15.3-5 A 9-hole distal femur LISS plate is slid through the submuscular tunnel. No prior tunnel preparation using any special instrument is necessary. Fixation is performed following confi rmation of correct LISS position. Proximal screws are inserted via multiple stab incisions using the handle as an external guide.

a

b

Fig 15.3-6a–b Postoperative x-rays show good anatomical alignment and fracture reduction.

252

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15.3

6

Femur, distal: extraarticular fracture, simple 33-A1

Rehabilitation

Physiotherapy starts on the fi rst postoperative day. Partial weight bearing is allowed 2 weeks after surgery to be progressed to full weight bearing 6 weeks postoperatively.

a

b

Fig 15.3-7a–b

4-months postoperative x-rays show callus formation. No loosening of fi xation.

7

a

b

Fig 15.3-8a–b

6-months follow-up: patient had minimal pain and satisfactory range of knee motion.

Pitfalls –

8

Pearls +

Pitfall 1

Pearl 1

Fracture is very unstable and there is a high risk of malalignment.

Correct realignment has to be achieved and temporarily maintained prior to LISS insertion.

Pitfall 2

Pearl 2

In osteoporotic bone, there is a risk of screws becoming loose especially in the diaphysis where screws are applied monocortically.

In osteoporotic bone, bicortical LHS fi xation is recommended in the diaphysis instead of monocortical screw fi xation to reduce the chances of implant loosening.

253

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16

Tibia and fibula, proximal

1

Introduction

255

Cases

1.1 1.2

Classification

255

16.1

Assessment

256

fracture, articular simple, metaphyseal

1.3

Indications and contraindications for MIPO

257

simple–41-C1

2

Surgical anatomy

257

3

Preoperative planning

258

3.1

Implants and instrumentation

258

4

Temporary skeletal fixation

260

5

OR set-up

260

5.1

Anesthesia

260

5.2

Patient positioning and image intensifier

260

6

Operative procedure

261

6.1

Articular fracture reduction and fixation

261

6.2

Indirect reduction of the articular block to the

16.2

Tibia and fibula, proximal: complete articular

Tibia and fibula, proximal: partial articular fracture, pure split–41-B1

6.3

diaphysis

261

Plate insertion and fixation

261

16.3

265

269

Tibia and fibula, proximal: extraarticular fracture, metaphyseal, multifragmentary—41-A3 with diaphyseal involvement

275

Teaching video on DVD-ROM 16

Tibia, proximal—anterolateral approach

6.3.1 Lateral approach 6.3.2 Medial approach

7

Postoperative care

264

8

Pitfalls

264

9

Pearls

264

10

Suggested reading

264

254

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Authors

16

1

Merng Koon WONG, Suthorn BAVONRATANAVECH

Tibia and fibula, proximal

Introduction

Fractures of the proximal tibia include a variety of fracture patterns that range from the simple to the very complex. While the treatment of simple fractures is fairly established and noncontroversial, this is not the case with the complex fractures. Complex fractures are often the result of high-energy injuries and are hence associated with severe soft-tissue damage, considerable comminution, and malalignment. They pose a challenge to management as they are difficult to reduce, realign, and stabilize. The results of treatment of these fractures using conventional plating methods have been disappointing as complications are common, particularly wound breakdown, infection, and loss of reduction leading to malunion and nonunion. Several recent developments, however, have led to improvement in the results of treatment of these fractures. These include: Indirect reduction techniques Preservation of soft tissue and vascularity by using minimally invasive plating techniques Improving the quality of fi xation with the use of angular stable locking compression plates 1.1

a

b

c

Fig 16-1a–c

41-A extraarticular fracture. a 41-A1 avulsion b 41-A2 metaphyseal simple c 41-A3 metaphyseal multifragmentary

a

b

c

Fig 16-2a–c

41-B partial articular fracture. 41-B1 pure split b 41-B2 pure depression c 41-B3 split-depression a

Classification

A proper understanding of the pathoanatomy of fractures of the proximal tibia is essential in order to carry out the appropriate treatment procedures. The Müller AO Classification distinguishes between extraarticular (type A), partial articular or unicondylar (type B), and complete articular or bicondylar (type C) fractures (Fig 16-1, Fig 16-2, Fig 16-3).

a

b

c

Fig 16-3a–c

41-C complete articular fracture. 41-C1 articular simple, metaphyseal simple b 41-C2 articular simple, metaphyseal multifragmentary c 41-C3 articular multifragmentary a

255

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1

Introduction

(cont)

Certain fracture patterns are associated with high-energy injuries. These include isolated medial tibial plateau fractures (41-B2.2 and 41-B3.2) and bicondylar fractures (41-C1, 41-C2 and 41-C3). The significance of these fractures lies in the fact that they are often associated with severe soft-tissue and neurovascular injuries as well as compartment syndrome. The recognition of these fractures should alert the surgeon to the need for careful assessment and of the potential hazards that may accompany their management. 1.2

Fracture morphology by means of imaging studies which include: Plain x-rays including AP, lateral, and oblique views Traction fi lms CT scan with 3-D reconstructions (Fig 16-4) MRI if needed, to assess soft-tissue injuries including meniscal tears and ligamentous disruptions Arteriogram if arterial injuries are suspected Soft-tissue envelope: Open wounds Swelling Abrasions Blisters Neurovascular status of the limb, especially the integrity of the: Common peroneal nerve Popliteal artery Anterior tibial artery and trifurcation

Assessment

In addition to conducting a thorough physical examination to ascertain the patient’s general condition and to exclude any associated injuries, the following should be carefully assessed:

d

c

e

Fig 16-4a–e a

b

a–b

c–e

AP/lateral x-rays of a medial tibial plateau fracture. The lateral view is far more instructive showing two main fragments split coronally with a step between them. CT scans clearly demonstrate the severity and complexity of the injury.

256

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16

1

Tibia and fibula, proximal

Introduction

(cont)

Compartment syndrome, which should be monitored with regular: Physical examination Compartment pressure measurement 1.3

Indications and contraindications for MIPO

Not all proximal tibial fractures require MIPO fi xation techniques. For simple metaphyseal fractures (41-A2), pure split (41-B1) or pure depression (41-B2) fractures of the lateral tibial plateau, conventional methods of fi xation are adequate. For certain high-energy injuries of the proximal tibia, however, MIPO is particularly beneficial as further damage to the soft tissue and blood supply at the fracture zone is less likely.

2

Examples of high-energy fractures that may be suitable for MIPO are 41-B2.2, 41-B3.2, 41-C1, 41-C2, and 41-C3 fractures. MIPO can be further assisted if the surgeon is proficient with arthroscopic reduction of intraarticular fractures. A word of caution on performing arthroscopy in an acute fracture setting is the risk of water extravasation into the leg compartments if the operation is prolonged. MIPO should not be considered in severe contaminated open fractures, infections, vascular injuries, and compartment syndrome.

Surgical anatomy

The medial plateau of the tibia is larger than the lateral plateau which is also more elevated. The former articular surface is concave while the latter is convex. Unless these facts are kept in mind, screws that are inserted proximally from lateral to medial run the risk of penetration of the medial joint surface. The tibial plateau has a posterior slope of about 7°; therefore any anteroposterior screw should be targeted in a slight posterodistal direction. The bony surfaces are relevant to plate contouring, especially when using conventional plates. The tibial plateau is roughly rectangular in cross-section, with a distal transition to a triangle in the shaft area. This must be taken into account when longer plates are used; they have to be contoured accordingly.

There are two main areas of neurovascular risk in MIPO around the knee: the popliteal vessels and nerves within the popliteal fossa (Fig 16-5a) and the trifurcation (Fig 16-5b) at the origin of anterior tibial vessels situated at the top of the interosseous membrane. Near the ankle, the deep peroneal nerve and anterior tibial vessels are in close relation to the anterior tibial border. Applying percutaneous screws onto a lateral plate may injure them, especially with long plates extending to the distal half of the tibia. The superficial peroneal nerve also crosses the distal third of the anterolateral surface of the tibia obliquely from posterior to anterior.

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2

Surgical anatomy

(cont) 3

1

7

9 2 10 4 6 5

11 12

8 9 7

1

Popliteal artery

2

Popliteal vein

3

Tibial nerve

4

Common peroneal nerve

5

Superior medial genicular artery

6

Superior lateral genicular artery

7

Inferior medial genicular artery

8

Inferior lateral genicular artery

9

Posterior tibial recurrent artery

10 Anterior tibial artery 11 Deep peroneal nerve 13

14 a Fig 16-5a–b

3

b

12 Superficial peroneal nerve 13 Medial malleolar artery 14 Lateral malleolar artery

Anatomy of tibia.

Preoperative planning

The preoperative plan (Fig 16-6) should address the following issues: Timing of surgery Reduction methods Management of the intraarticular component of the fracture when present The surgical approach Type of plate to be used, including its length, the number and position of screws, and their order of insertion The need for bone grafting The need for supplementary fi xation

3.1

Implants and instrumentation

Although conventional plates (DCP and LC-DCP) can be used, angular stable plates such as the LCP or LISS for proximal tibia (Chapter 4 Implants) are preferred as they have specific features that enhance minimally invasive indirect reduction and fi xation techniques. The angular stability provided by these locking implants allows for the simultaneous stabilization of both medial and lateral plateaus using a single approach.

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16

3

Tibia and fibula, proximal

Preoperative planning

(cont)

An external fi xator or large distractor may be required to achieve indirect reduction.

particularly useful tool (Chapter 7 Reduction techniques: Fig 7-1).

Pointed reduction forceps and K-wires may be needed to temporarily hold reduced fracture fragments. The large “King Tong” reduction clamp of the pelvic instrument set is a

If arthroscopic guided reduction and fi xation of the intraarticular fracture component is planned, set up for arthroscopic surgery is necessary.

1 2 4

3 6 5

a

b

c

d

Fig 16-6a–d

A step-by-step preoperative plan of the surgical procedure: Fracture fragments are traced and the type and length of the plate to be used templated. The degree of precontouring of the plate that is required is also determined. b After the plate has been introduced, a cortex screw (1) is inserted into the most proximal hole to stabilize the plate. A locking head screw (LHS) (2) is inserted at the second hole proximally. c Manual traction is applied and fracture reduction is performed after which an additional cortex screw (3) is inserted distally near the fracture. Length and axial alignment are compared with the intact limb. d Three additional LHS (4–6) are inserted alternatively on each side of the fracture to complete the fracture fi xation. The fi rst cortex screw inserted proximally may be replaced by an LHS if desired. a

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4

Temporary skeletal fixation

Temporary skeletal fi xation may be required if for any reason defi nitive MIPO surgery is delayed, such as in the presence of severe soft-tissue swelling, skin abrasions or blisters, and open fractures after initial wound debridement. Usually, a unilateral, bridging external fi xator is applied using two Schanz screws applied anteriorly in the femoral shaft and two Schanz screws to the anterior tibia distally to maintain length, rotation, and axial alignment. The “3-tube” mode is useful to

5

OR set-up

5.1

Anesthesia

General or regional anesthesia may be used, depending on the condition of the patient and on the preference of the anesthetist. 5.2

Patient positioning and image intensifier

The patient is usually placed supine on a radiolucent operating table. A sterile roll is placed under the knee to keep it flexed. This helps to facilitate fracture reduction, and also reduces the risk of injury to the popliteal vessels (Fig 16-7). Alternatively, an operating table that can be adapted to allow the knee to be flexed to 90º if necessary may be used.

allow knee flexion and repositioning during the subsequent MIPO procedure. When applied, this external fi xator frame can be retained during the defi nitive MIPO procedure to serve as a reduction tool. Alternatively, the large distractor may be used, with one pin in the center of the rotational axis in the femoral condyle on the opposite side of the desired plate position, and the other pin in the tibial shaft.

A roll under the buttock of the injured side allows the patella to point directly anterior. This improves the accuracy of AP and lateral images when using the image intensifier. The use of a tourniquet is to be avoided if possible. The injured limb is then cleaned and draped in the usual manner. The anterior iliac crest is also prepared in case bone grafting is necessary, unless the use of bone substitutes is intended. Anatomical landmarks, including the patella, medial, and lateral joint lines, tibial tuberosity, fibular head, as well as the hip center and center of the talar dome are marked.

After the patient is anesthetized, and before preparing and draping the injured limb, the length of the contralateral uninjured limb is measured and the degree of external rotation of the foot with the knee flexed and extended noted for subsequent reference. The uninjured limb can then be placed on a leg holder to allow the image intensifier to be positioned on the opposite side of the operating table to take AP and lateral views of the injured proximal tibia.

Fig 16-7 The patient is placed supine on a radiolucent operating table with a roll to support knee in flexion.

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16

6

Tibia and fibula, proximal

Operative procedure

The operation should be carried out in the following sequence: Articular fracture reduction and fi xation Indirect reduction of the reconstructed articular block to the diaphysis Plate insertion and fi xation

resultant metaphyseal defect fi lled with bone graft or bone substitute and the “opened” condylar fragment repositioned.

6.1

The quality of the articular reduction can be assessed by means of arthroscopy, image intensification, or submeniscal arthrotomy.

Articular fracture reduction and fixation

Displaced intraarticular fractures can be reduced by ligamentotaxis using manual traction, a large distractor or external fi xator bridging a slightly flexed knee. A Schanz screw or a 2.5 mm K-wire can be used as a joystick for manipulation. In split depression fractures, the depressed articular fragment is exposed by hinging open the split condylar fracture fragment. The depressed fragment is then elevated directly, the

Once articular fracture reduction is accomplished, the reduction can be maintained with K-wires or large pointed reduction forceps.

Defi nitive fi xation is then carried out with partially threaded cancellous bone screws used as lag screws (Fig 16-8), care being taken that the position of these screws does not interfere with the subsequent placement of the buttress plate. The more recent technique of 3.5 mm “raft plate” and multiple screws placed under the subchondral plate is another option. 6.2

Indirect reduction of the articular block to the diaphysis

The metaphyseal-diaphyseal component of the fracture is next reduced using indirect reduction methods such as manual traction, flexing the knee using a roll or by adapting the operating table, joysticks, a knee-bridging external fi xator or large distractor, if one has not been previously applied. 6.3

a

b

c

Fig 16-8a–d a

The split condylar fragment is hinged open. b The depressed fragment is elevated and the reduction is maintained with a pelvic clamp. c Repositioning and fi xation of the split condylar fragment with two lag screws.

Plate insertion and fixation

Most fractures of the proximal tibia can be treated by a single approach especially when angular stable LCP are used. This approach may be either lateral or medial. The choice of the approach depends on the location of the main fracture pathology.

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6 6.3.1

Operative procedure

(cont)

Lateral approach

Fracture reduction and plate position are checked with the image intensifier. Minor degrees of varus–valgus or translation malalignment can be corrected using a pull reduction instrument which is placed through the insertion guide and plate hole to pull or push bone fragments in relation to the plate.

The lateral approach is more commonly used as the lateral column is more frequently fractured than the medial column. There are, however, disadvantages associated with the lateral approach for plate insertion. These include: The proximal attachment of the tibialis anterior muscle needs to be detached for approximately 2–3 cm to allow the submuscular passage of the plate. This results in some degree of devitalization at the fracture zone. There is a potential risk of compartment syndrome as the plate occupies space in the anterior osteofascial compartment. When a long plate is used, there is a risk of injury to the superficial peroneal nerve. A laterally placed implant may not adequately fi x an unstable, dislocated posteromedial fragment, which may require a separate posteromedially inserted buttress plate. If available, the LISS for proximal tibia should be used as this plate is specially designed for lateral application (Fig 16-9). The main steps in the application of this plate using the lateral approach are: A lateral straight or curved incision is made from Gerdy’s tubercle extending distally for about 5 cm. The proximal attachment of the tibialis anterior muscle is detached for approximately 2–3 cm distally. The LISS plate is fi xed on to the insertion guide. The plate is passed distally between the tibialis anterior and periosteum under fluoroscopic guidance until the plate is properly seated on the flare of the lateral tibial plateau. A K-wire is inserted through a hole in the proximal end of the insertion guide into the proximal tibia parallel to the joint surface. After confi rming that the distal end of the plate is centered on the tibial shaft, a second K-wire is inserted through the most distal plate hole through a stabilization bolt.

a Fig 16-9a–b a

Lateral straight or curved incision is made from Gerdy’s tubercle extending distally for about 5 cm.

b b

An LISS for proximal tibia is fi xed with the aid of the insertion guide.

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16

6

Tibia and fibula, proximal

Operative procedure

(cont)

Screw insertion is then carried out. The last screws to be inserted are through the holes where the K-wires were inserted earlier to stabilize the plate to the tibia. Removing the stabilization bolt and K-wire from the most distal plate hole before the insertion of the rest of the diaphyseal screws will result in loss of orientation of the insertion guide with the remaining plate holes. Similarly, removing the fi xation bolt and K-wire from the proximal plate hole before the rest of the screws are inserted will result in loss of orientation between the plate and guide (Fig 16-9b). If locking head screws (LHS) are used, they should be inserted using the hexagonal screwdriver shaft 3.5 mm with high-speed power and tightened with a torque limiting screwdriver. A minimum of three screws is recommended for each main fracture fragment, with more screws inserted in the case of osteoporotic bone. 6.3.2

Medial approach

A medial approach can be adopted if most of the comminution is medial or if muscle stripping from the lateral column is undesirable. As the medial cortex of the tibia is subcutaneous, no muscle stripping is necessary. The medial approach is contraindicated if the major part of the fracture involves the lateral column or if the skin over the medial aspect of the proximal tibia is badly contused.

The main steps in the application of MIPO using the medial approach are: The shape of the contoured plate is marked out on the skin to determine the location of the incisions needed. A 2 cm longitudinal medial incision is made directly over the proximal tibia (Fig 16-10). A subcutaneous, extraperiosteal tunnel is created and the plate is then passed into this tunnel. The position of the plate is checked by x-rays. It should be centered on the tibial shaft distally. The plate is temporarily fi xed to the tibia using K-wires through the most proximal and distal plate holes. The length, rotation, and axial alignment of the limb are checked. The K-wires are replaced with screws. Fracture reduction and plate position are checked again and any adjustments made if needed. If satisfactory, the rest of the screws are inserted. At least three screws are inserted bicortically into each main fracture fragment. In the presence of a fibular fracture and metaphyseal comminution in the tibia, and when a conventional plate is used, it may be useful to fi rst fi x the fibula so that it can act as a fulcrum for tibial alignment in the frontal plane. Fixation of the fibula is not necessary when an angular stable LCP is used.

Suitable implants for the medial approach include the LCP metaphyseal plate, and conventional DCP, or LC-DCP 4.5 mm. As these plates are not specifically designed for the proximal tibia, some degree of contouring, especially in the case of the conventional plates, is necessary.

Fig 16-10

Medial incision is made directly over the proximal tibia. 263

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7

Postoperative care

Active range of motion of the knee joint is started early. A continuous passive range of motion machine may be used if necessary. Toe-touch weight bearing on the affected side is

8

Pitfalls –

encouraged from the second postoperative day. As fracture healing progresses, the degree of permitted weight bearing is also increased.

9

Pearls +

Pitfall

Pearl 1

When inserting the proximal tibia LISS through the lateral approach, care must be taken to ensure that the proximal end of the plate is positioned correctly on the lateral tibial plateau. If the plate is placed too posteriorly or rotated too anteriorly, there is a risk of a screw penetrating the posterior cortex and injuring the popliteal artery or peroneal nerve. If the plate is placed too proximally, there is a risk of a screw penetrating the articular surface.

Preliminary insertion of a K-wire through the proximal plate hole using a K-wire insertion sleeve will indicate whether surface penetration is likely. If so, the position of the plate should be adjusted or a shorter screw may be used.

Pearl 2

During plate insertion into the submuscular or subcutaneous tunnel, the distal tip of the plate should be kept in contact with the anterior crest of the tibia by observation or palpation so that its progress can be monitored and posterior migration of the plate into neurovascular structures avoided.

Pearl 3

When a long plate is inserted using the lateral approach, it is advisable to make a longer distal incision to check that the plate is centered on the tibial shaft and to avoid injury to the superficial peroneal nerve.

10

Suggested reading

Berkson EM, Virkus WW (2006) High-energy tibial plateau

Rüedi TP, Murphy WM (2001) AO Principles of Fracture Management.

fractures. J Am Acad Orthop Surg; 14(1):20–31.

Stuttgart, New York: Georg Thieme Verlag.

Krettek C, Gerich T, Miclau T (2001) A minimally invasive medial

Stannard JP, Wilson TC, Volgas DA, et al (2004) The less invasive

approach for proximal tibial fractures. Injury 2001; 32 Suppl:SA4–14.

stabilization system in the treatment of complex fractures of the tibial plateau: short-term results. J Orthop Trauma; 18(8):552–558.

264

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Author

Merng Koon WONG

16.1 Tibia and fibula, proximal: complete articular fracture, articular simple, metaphyseal simple–41-C1 1

Case description

A 61-year-old female with a left tibial plateau fracture, after falling into a drain. Low-energy, closed fracture.

a

b

c

Fig 16.1-1a–c a–b X-rays of the left knee show intraarticular lateral plateau

fracture and extraarticular medial fracture line.

2

c

Preoperative valgus deformity compared to uninjured right knee.

Indication for MIPO

Intraarticular step deformity would result in posttraumatic arthrosis.

Due to the extensive medial hematoma and soft-tissue damage, a

Therefore, anatomical reduction and stable fi xation are mandatory.

medial incision should be avoided. A small lateral incision will avoid skin necrosis and subsequent infection.

Use of an angular stable implant placed laterally avoids the need for a medial buttress which would require a separate medial incision with extensive medial subcutaneous dissection.

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16

3

Tibia and fibula, proximal

Positioning

4

Surgical approach

The patient is positioned supine on a radiolucent operating table, with the distal end dropped to allow 90° knee flexion and fracture distraction by gravity. This position facilitates the intraarticular part of the surgery including submeniscal arthrotomy, fracture reduction and stable fi xation. The image intensifier is positioned on the opposite side of the operating table.

Fig 16.1-2 Anterolateral incision with submeniscal arthrotomy. Elevation of anterior part of lateral meniscus with stay sutures allows accurate visual reduction of lateral tibial plateau. Wedge fracture is displaced posterolaterally.

5

Reduction

a

b

Fig 16.1-3a–b a

Depressed articular fragments are elevated en bloc with a punch and supported with impacted bone graft.

b

The two wedge fragments are reduced anatomically using a large pointed reduction clamp.

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16.1

5

Tibia and fibula, proximal: complete articular fracture, articular simple, metaphyseal simple–41-C1

Reduction

(cont) Fig 16.1-4a–b

Reduction is monitored by an image intensifier. K-wires are used for temporary fi xation. The reduced articular block is fi xed to the tibial shaft with an L-buttress LCP. First, correct alignment and length are confi rmed. Next, the plate is inserted submuscularly. A cortex screw is inserted to hold the plate in the correct position. Locking head screws (LHS) are inserted into proximal plate holes. The reduction of the articular fracture is maintained during LHS insertion. Extraperiosteal plate insertion and gentle handling of skin bridge and soft tissue are essential for preservation of the periosteum and blood supply.

a

6

b

Additional compression screws may be required for buttress reinforcement.

Fixation

Fig 16.1-5a–b a

a

b

Sequence of screw insertion. b Distally three LHS have been inserted percutaneously. The LCP screw holes are targeted using another similar implant as a template over the skin to guide the skin incisions. The threaded drill sleeve for the LHS serves as guide for proper direction of drilling if it is secure on engagement.

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16

7

a

Tibia and fibula, proximal

Rehabilitation

b

c

Fig 16.1-6a–c Postoperative x-rays. The fracture healed in 8 weeks, whereupon full weight bearing was allowed. X-rays 2 years after surgery show perfect anatomical restoration of the lateral joint line.

268

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Author

16.2 1

Merng Koon WONG

Tibia and fibula, proximal: partial articular fracture, pure split–41-B1

Case description

A 54-year-old male fell while riding his motorcycle and sustained a 41-B1 fracture at the left knee.

Fig 16.2-1a–d a

Left knee 41-B1 fracture with intraarticular lateral plateau depression in AP view. The radiological features are subtle but clear in comparison to the right knee. b–c A depression of 10 mm of the central portion of the lateral tibial plateau is visible compared to the uninjured knee. d Oblique view clearly shows the loss of the convexity of the lateral tibial plateau.

a

b

c

d

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16

2

Tibia and fibula, proximal

Indication for MIPO

The intraarticular step deformity in the lateral tibial plateau would

CT scans were utilized to localize the exact position of the joint

result in valgus instability of the knee joint with weight bearing and

surface depression as well as to confirm the 10 mm depth of the

subsequent posttraumatic arthritis. Anatomical reduction of the

depressive fracture.

articular fracture and rigid stabilization are required.

a

b

c

Fig 16.2-2a–c a

Coronal CT image posterior to the fi bular head.

b

Sagittal CT image of the posterior tibial plateau. This implies an open approach would have to split coronally through the anterior half of the lateral plateau to allow impaction bone grafting to effect elevation of the depressed lateral tibial plateau.

c

Outlines the percentage area of the lateral tibial plateau involved.

The tibial plateau fracture 41-B1 is treated by minimally invasive osteosynthesis (MIO).

3

Positioning

Patient is placed in supine position with the leg in extension on a radiolucent operating table.

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16.2

4

Tibia and fibula, proximal: partial articular fracture, pure split–41-B1

Surgical approach and reduction

a Fig 16.2-4a–b

K-wire under fluoroscopic guidance is used to target the depressed lateral tibia plateau.

Fig 16.2-3

An anterolateral oblique incision is made over the outline of the lateral tibial plateau.

a

b

Fig 16.2-5a–d a–b

b

The cortical undersurface of the lateral tibial plateau is cored out using an appropriate sized punch from a cannulated boneharvesting set.

c c–d

d

The cortical surface of the harvested bone plug is turned upward and impacted into the most depressed portion of the fracture. The smooth surface of the autogenous bone serves to prevent protrusion of the metal punch tip through the fracture into the knee joint.

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16

4

Tibia and fibula, proximal

Surgical approach and reduction

a

(cont)

b

c

Fig 16.2-6a–c

Image guidance is used to elevate the lateral depressed tibial plateau to the correct height. Arthroscopic assisted reduction is also possible but care must be taken to prevent compartment syndrome caused by arthroscopic water pressure.

5

Fixation

a Fig 16.2-7a–b

b

An additional bone graft is always required to gain stability by overpacking the cavity created by the elevation of the depressed plateau fracture. This grafted area is buttressed by a plate to prevent loss of bone graft.

Fig 16.2-8 The 4.5 cm wound, which is 1/3 of that required for open impaction bone grafting in a lateral plateau depression fracture.

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16.2

5

Tibia and fibula, proximal: partial articular fracture, pure split–41-B1

Fixation

(cont)

a

b

c

Fig 16.2-9a–c

CT images after surgery (same views as preoperatively; Fig 16.2-2) demonstrate restoration of the depressed articular fracture.

6

Rehabilitation

Patient’s knee was placed on continuous passive motion (CPM) for the fi rst 3 days and subsequently allowed full weight bearing within 4 weeks after surgery.

a

b

Fig 16.2-10a–b

10 weeks postoperative x-rays show good reduction and fracture healing.

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16

6

Tibia and fibula, proximal

Rehabilitation

a Fig 16.2-11a–d

(cont)

b

c

d

Full range of motion of left knee, allowing a full squat at 6 months after surgery.

274

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Author

Frankie KL LEUNG

16.3 Tibia and fibula, proximal: extraarticular fracture, metaphyseal, multifragmentary—41-A3 with diaphyseal involvement 1

Case description

A 24-year-old male sustained a Gustilo type ll open fracture of the proximal left tibia. There was a deep 2 cm wound in the posterior calf. The fracture extended into the diaphysis. The initial treatment consisted of wound debridement followed by external fi xation. Defi nitive fi xation was carried out 3 days later.

a

b

Fig 16.3-1a–b The multifragmentary fracture involved the proximal tibial metaphysis and there was a fibular fracture at the same level.

Fig 16.3-2a–b

a

b

Temporary stabilization with external fi xation. Note that the posterior wound has been debrided and sutured.

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16

2

Tibia and fibula, proximal

Indication for MIPO

Operative treatment was indicated for this patient, as the fracture

alternative. But the placement of half pins near the knee joint would

was unstable and could not be adequately immobilized by a cast.

affect range of motion, and there would also have been a risk of pin tract infection. Furthermore, the stability achieved by external fi xa-

The use of an intramedullary nail was not selected in view of the

tion is generally inferior to that achieved by internal fi xation.

proximal extent of the fracture; the comminution at the proximal metaphysis would preclude successful proximal locking. Conven-

The insertion of a LISS as a bridging internal fi xator was the treatment

tional compression plating was not suitable either as it would

of choice. The short proximal tibial fragment posed great diffi culty in

involve extensive surgical trauma; the dissection would cause

screw placement, but the use of locking head screws (LHS) greatly

devascularization of the fracture fragments, and fracture healing

improved the proximal fi xation. Angular stability by lateral fi xation

would be impaired. External fi xation would have been an acceptable

also made medial fi xation unnecessary.

3

Positioning

Patient placed in supine position with a supporting pad beneath the knee.

4

Surgical approach

a

b

Fig 16.3-3a–b a

Pin tracks are cleaned and part of the external fi xator is removed to allow space for internal fi xation. A small incision is made over the anterolateral aspect of proximal tibia.

b

LISS is introduced into a submuscular tunnel without tunnel preparation using other instruments.

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16.3

5

Tibia and fibula, proximal: extraarticular fracture, metaphyseal, multifragmentary—41-A3 with diaphyseal involvement

Reduction and fixation

a

b

Fig 16.3-4a–b a

6

When the correct position is confi rmed with an image intensifier, K-wires are inserted as a preliminary fi xation.

b

Fixation is completed using self-drilling screws. The external fi xator is then removed.

Rehabilitation

No additional immobilization is required. A compression bandage is applied to control swelling. Range of motion exercises started from fi rst postoperative day. Partial weight bearing was allowed 2 weeks after surgery and progressed to full weight bearing at 6 weeks.

a

b

Fig 16.3-5a–b Postoperative x-rays show that a precise reduction of the diaphyseal fragments was not necessary. Correct axial and rotational alignment of the tibia was achieved.

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16

6

a

Tibia and fibula, proximal

Rehabilitation

(cont)

b

Fig 16.3-6a–b X-rays at 6 months postoperatively show alignment was maintained.

a

b

a

b

Fig 16.3-7a–b At 6-month follow-up, patient had minimal pain and satisfactory range of knee motion.

Fig 16.3-8a–b

X-rays at 12 month show solid bone healing.

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16.3

7

Tibia and fibula, proximal: extraarticular fracture, metaphyseal, multifragmentary—41-A3 with diaphyseal involvement

Pitfalls –

8

Pearls +

Pitfall

Pearl

The fracture is very unstable and there is a risk of tibial malalignment.

Correct realignment of the fracture must be achieved and maintained before the insertion of the LISS. A simple external fi xator can maintain the reduction and greatly facilitates the procedure.

279

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17

1

Tibia and fibula, shaft

Introduction

281

1.1

Classification

281

1.2

Current methods of treatment

281

1.3

Indications for MIPO

282

1.4

Contraindications for MIPO

282

2

Surgical anatomy

283

2.1

Structures at risk

283

2.2

Cross-sectional anatomy

283

2.3

Assessment

285

3

Preoperative planning

285

4

OR set-up

286

4.1

Patient positioning and image intensifier

286

4.2

Choice of implant and plate contouring

286

4.3

Determining the plate length and number of the screws

287

5

Operative procedure

287

5.1

Surgical approach

287

5.2

Medial approach

287

7

Pitfalls

292

8

Pearls

292

9

Suggested reading

294

Cases 17.1

Tibia and fibula, shaft: wedge fracture, fragmented wedge–42-B3

17.2

295

Tibia and fibula, shaft: wedge fracture, fragmented wedge–42-B3

299

5.2.1 Incisions and percutaneous insertion of the plate 5.2.2 Reduction technique 5.2.3 Plate fixation proximally 5.2.4 Fracture reduction and distal plate fixation 5.3

Lateral approach

290

6

Postoperative care

291

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Authors

17

1

Theerachai APIVATTHAKAKUL, Kok-Sun KHONG

Tibia and fibula, shaft

Introduction

Fractures of the tibial shaft are one of the most common longbone fractures encountered in orthopedic practice. Recent trends have tended to favor operative fi xation as patients today are less willing to tolerate the inconvenience of conservative methods of treatment, and are also less forgiving of anything more than minor degrees of limb length discrepancy or malalignment. Operative treatment of tibial shaft fractures includes a variety of options, most of which are relatively well established. Minimally invasive plate osteosynthesis (MIPO) is gradually evolving as the treatment of choice, should the plate be favored as a method of fracture fi xation. 1.1

b

c

Fig 17-1a–c

42-A simple fracture. a 42-A1 spiral b 42-A2 oblique (≥ 30°) c 42-A3 transverse (< 30°)

Classification

According to the Müller AO Classification the tibial shaft is identified by the number 42. In the tibial shaft, the fractures are either simple fractures (type A) or multiframentary fractures. Multifragmentary fractures are divided into wedge (type B) and complex fractures (type C) (Fig 17-1, Fig 17-2, Fig 17-3). 42-B and 42-C fractures are ideally suited for MIPO. Tibial shaft fractures may be open or closed and are often associated with severe soft-tissue injuries. Consideration of the wound and soft-tissue damage is important when treating open tibial fractures by MIPO techniques. 1.2

a

a

b

c

Fig 17-2a–c

42-B wedge fracture. 42-B1 spiral wedge b 42-B2 bending wedge c 42-B3 fragmented wedge a

Current methods of treatment

Intramedullary nailing

The intramedullary nail is the treatment of choice for simple, closed tibial shaft fractures in the middle two quarters. The locking bolts of the intramedullary nail provide better stability and extend the indications for both reamed and unreamed nailing. Preservation of blood supply at the fracture site improves bone healing when compared to open plating.

a

b

c

Fig 17-3a–c

42-C complex fractures. 42-C1 spiral b 42-C2 segmental c 42-C3 irregular a

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1

Introduction

(cont)

However, in some situations intramedullary nailing is contraindicated: Small or deformed medullary canals Severe soft-tissue injury Compartment syndrome Vascular injury requiring repair Gross contamination of the medullary canal Fractures with proximal or distal articular extensions Plating

Plates are usually indicated for tibial shaft fractures when intramedullary nailing is not suitable. Conventional plate fi xation requires more soft-tissue dissection than intramedullary nailing, and is usually associated with more wound complications. The recent technique of percutaneous plate fi xation, using the principle of bridge plating, is associated with fewer wound problems and improved rates of fracture healing. External fixation

External fi xation is not only indicated in open fractures but also in closed fractures where there is severe soft-tissue injury. It can be used for temporary or defi nitive fi xation. The technique of modular external fi xation allows more freedom of pin placement in both fracture fragments so as to avoid placing them through open wounds. Problems associated with external fi xators in the tibia include: Pin-track infections Patient inconvenience Delayed union Difficulty in conversion to intramedullary nail fi xation

External fi xators can also be used for preoperative or intraoperative reduction of the fracture prior to percutaneous plating. 1.3

Indications for MIPO

MIPO can be performed in most closed tibial fractures. In fact, this is the commonest fracture in which the MIPO technique is applied and also the easiest fracture for the beginner to start with. MIPO is most suitable for: Multifragmentary fractures Fractures extending to the articular surfaces Segmental fractures Small medullary canals (< 9 mm) Deformed shaft (malunions) Open growth plates 1.4

Contraindications for MIPO

Contraindications are relative, and pertain to the planned approach of inserting the implant. One should not consider using MIPO in the following situations: Severe soft-tissue loss with no coverage of exposed bone Associated vascular injuries Compartment syndrome Pathological fractures Osteomyelitis Delayed surgery with shortening of the limb Delayed reconstructions (eg, requiring bone grafting)

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17

2

Tibia and fibula, shaft

Surgical anatomy

In MIPO of the tibial shaft, the plate may be placed either on the medial or on the lateral surface. The medial surface is easily palpable and it is easier to prepare the subcutaneous tunnel here. However, in patients whose skin and subcutaneous tissues are thin, such as the elderly, the problem of hardware prominence, neuroma formation or skin necrosis must be considered. The lateral surface is within the anterior compartment, and placing a plate there may compromise the blood supply to the mid- and distal shaft. The posterior surface is deep and is not suitable for MIPO. 2.1

Structures at risk

Medial surface of the tibia

There are two structures to be particularly aware of: Saphenous nerve (including its infrapatellar branch) Saphenous vein The saphenous nerve emerges from between the gracilis and sartorius and runs parallel to the long saphenous vein. From the posteromedial aspect of the knee, it gives off the infrapatellar branch which runs across to the anterior aspect of proximal tibia (Fig 17-4). If the infrapatellar branch is cut, its ends should be buried in the subcutaneous fat to minimize the chance of formation of a painful neuroma.

Lateral surface of the tibia

There are three structures to be aware of: Anterior tibial vessels Superficial and deep branches of the peroneal nerve Superior and inferior syndesmoses In the proximal and midshaft of the tibia, there are no structures at risk and it is safe for tunneling and plating. In the distal tibia, the deep peroneal nerve, along with the anterior tibial vessels, lies superficially over the anterior aspect of the distal tibia. These important structures have to be identified and protected before tunneling and plate fi xation. It is advisable to prepare the tunnel right against the bone from the distal tibia to the midshaft to avoid injury to the deep peroneal nerve and anterior tibial vessels. When inserting screws in the distal third, a sleeve is of paramount importance in order to avoid damaging the above mentioned neurovascular structures. 2.2

Cross-sectional anatomy

The saphenous nerve and the long saphenous vein run along the posteromedial border of the tibia and then cross the distal tibia to lie anterior to the medial malleolus.

At the level of proximal tibial shaft (Fig 17-4a), the bone is triangular in shape and flat on the anteromedial surface. The anterior tibial vessels and deep peroneal nerve lie anterior to the interosseous membrane while the posterior tibial vessels and nerve lie posterior to the interosseous membrane. These neurovascular structures lie close to the posterolateral corner of the tibia. The long saphenous vein lies along the posteromedial crest of the tibia.

MIPO incisions on the medial side of the tibia should avoid injury to the saphenous nerve and vein by using blunt dissection and by identifying these structures should they be situated along the path of the incision. Tunneling should be done deep to the plane of the saphenous nerve and vein, especially in the distal tibia.

At the level of the midshaft of the tibia (Fig 17-4b), the bone is triangular in shape. The deep peroneal nerve and anterior tibial vessels move closer to the posterolateral corner of the bone while the posterior tibial vessels and nerve move to lie over the posterior aspect of the tibia. The long saphenous vein still lies along the posteromedial aspect of the tibia.

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2

Surgical anatomy

(cont)

Tibial nerve

Deep fibular nerve and anterior tibial artery a

and vein

Popliteal artery and vein Fibular artery, and vein

Sural nerve, short saphenous vein

b Tibial nerve, posterior

Anterior tibial artery and vein

tibial artery, and vein

Fibular artery

c

Fig 17-4a–c

Cross-sectional anatomy of the tibia. Proximal tibia b Midshaft tibia c Distal tibia a

Tibial nerve and posterior tibial artery and vein

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17

2

Tibia and fibula, shaft

Surgical anatomy

(cont)

At the level of the distal tibia (Fig 17-4c), the bone is circular in shape and is slightly flat in the posterior aspect. The anterior tibial vessels with the deep peroneal nerve move onto the anterolateral surface of the tibia and run close to the bone. The posterior tibial vessels and nerve move close to the posteromedial part of the tibia. The long saphenous vein moves from the posteromedial to the medial surface of the distal tibia.

3

2.3

Assessment

It is important to examine the skin and soft tissue surrounding the tibia and to distinguish open from closed fractures. Closed fractures with skin contusion, crushing, or necrosis indicate that the soft tissue and muscles within the leg compartments are severely damaged. The timing and method of treatment selected will depend on the severity of the soft-tissue injuries associated with the tibial fracture. MIPO should be performed after the soft-tissue swelling has subsided and the skin “wrinkle sign” is seen.

Preoperative planning

MIPO is technically more demanding than conventional plating. Indirect reduction and closed percutaneous fi xation techniques require careful preoperative planning to choose the appropriate implant size, length, number and position of screws, and their order of insertion. The length of the plate should be determined by a template prior to the operation. Step-by-step execution of the preoperative plan, starting with indirect fracture reduction, surgical approach, tunneling, plate insertion, and screw fi xation is necessary to ensure a good outcome.

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4 4.1

OR set-up Patient positioning and image intensifier position

The patient is placed supine on a radiolucent operating table. A support is placed under the knee to keep it in 60° flexion (Fig 17-5) so that lateral images can be taken with the image intensifier. The use of a pneumatic tourniquet is optional. 4.2

Choice of implant and plate contouring

The implants used in MIPO of tibial shaft fractures are the narrow LC-DCP or LCP with 12–16 holes. Contouring for nonlocking plates is not necessary at the midshaft region on both medial and lateral surfaces. However, if the fracture extends more proximally or distally, plate contouring becomes necessary. The plate can be precontoured using a plastic bone model or a dry bone and then sterilized. In most cases, the plate should fit the bone. However, in some cases, intraoperative “fi ne-tuning” of the plate contour may be necessary.

If the fracture extends to the proximal tibia and it is planned to apply the plate to the medial cortex, the plate needs to be precontoured in two planes. It needs to be bent in order to fit the medial flare of the tibial condyle and slightly twisted anteriorly at the upper end of the plate. On the lateral side, the plate is bent to fit the lateral tibial condyle and slightly twisted anteriorly at its upper end. For the medial side of the distal tibia, the plate is bent to fit the flare of the distal tibia and slightly twisted internally at the lower end of the plate by 20°–30° (Fig 17-6). On the lateral side, the lower third of the plate is bent to fit the anterolateral surface of the distal tibia anterior to the distal tibiofibular syndesmosis and slightly twisted anteriorly. Unlike the LC-DCP, the LCP with locking head screws (LHS) provide angular stability. Three LHS on each side of the fracture are stable enough to bridge the fracture. Of these, one screw should always be placed close to the fracture and

a Fig 17-5

Patient positioned with the knee in flexion.

b

Fig 17-6a–b

In the distal tibia it is important to properly contour the plate to fit the concavity and torsion of the medial surface.

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17

4

Tibia and fibula, shaft

OR set-up

(cont)

another in the end hole of the plate. No plate contouring is required for the midshaft of the tibia. For the proximal and distal tibia, the plate may need some precontouring but not necessarily anatomically because the plate does not cause primary loss of reduction as the LHS are inserted. 4.3

Determining the plate length and number of the screws

In multifragmentary fractures, the fracture is stabilized by applying the bridging plate principle. The length of the plate

5 5.1

remains controversial. With the MIPO technique, the plate length can be increased with minimal additional soft-tissue dissection. In multifragmentary fractures, it is preferable to use a longer plate that has a plate span ratio of more than 3 (that is, plate length more than three times the fracture length). The proximal and distal segments of the plate should be longer than the middle segment. It is not necessary to put screws in all the plate holes. See Chapter 2 (Mechanobiology) for details of recommended screw placement.

Operative procedure Surgical approach

In MIPO of tibial shaft fractures, the plate can be applied to either the medial or lateral surface depending on the condition of the soft tissue, the fracture configuration, and the preference of the surgeon. The medial plate is easier to insert but carries with it the problem of hardware prominence. The lateral plate lies deep under the muscles but it is more difficult to insert and fi x. The site of the major comminution will determine the approach. The plate should not be placed on the butterfly fragments so as to avoid devascularization during tunneling or plate insertion. Image intensification with the plate against the skin will allow marking of the screw holes to be used. 5.2

Medial approach

5.2.1

Incisions and percutaneous insertion of the plate

Choose the appropriate length of plate from preoperative planning. The bony landmarks are marked on the skin. Two 3–4 cm incisions are then made on the medial side of the leg close to the posteromedial border of the tibia corresponding to the ends of the plate to be used. The incisions are carried down to the periosteum (Fig 17-7). A subcutaneous extraperiosteal

tunnel is prepared for plate introduction by sliding a tunneler close to the bone from either distal to proximal or in the reverse direction. When the distal incision is made close to the medial malleolus, the saphenous vein and nerve should be identified and protected. Slip the plate into the tunnel with the guidance of a Kocher clamp or plate holder. When the tunneler is used, the end of the plate can be tied to the end of the tunneler with a suture so that, as the tunneler is withdrawn, the plate will be pulled back into the tunnel. 5.2.2

Reduction technique

The fracture is reduced by manual traction or with the help of a distractor or temporary external fi xator. The goal is to restore the length, and axial and rotational alignment of the limb. In a simple fracture pattern, especially that of the transverse fracture, it is more difficult to reduce the fracture and maintain the limb length and axis by closed manipulation than in the multifragmentary fracture pattern. In simple fracture patterns, it is advisable to consider a closed percutaneous anatomical reduction using the pointed reduction forceps or to make a small incision over the fracture site for direct anatomical reduction. 287

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5

Operative procedure

(cont)

a

b

Fig 17-7a–b a

Medial approach in tibial shaft fractures. Two 3–4 cm incisions, one proximally and one distally, according to the length of the plate.

In complex fracture patterns, exact reduction is not required and the plate should only bridge the fracture. Most of these fractures can be reduced by closed manipulation (manual traction or with a distractor). The modular external fi xator is a very helpful tool for the reduction of tibial shaft fractures. Two pins are inserted in each main fracture fragment. The position of the pins must be planned so as not to obstruct the subsequent plate insertion. Fix the two pins to a tube by universal clamps and use the tubes as handles for manipulation. After reduction, the two tubes are joined with a third tube and two tube-to-tube clamps (Fig | Anim 17-8b). Plating of the fibula may be helpful for indirect reduction and to improve the stability of multifragmentary fractures of the tibial shaft, especially at the proximal or distal thirds.

b

Care has to be taken at the distal incision to identify and protect the long saphenous vein and the saphenous nerve.

5.2.3

Plate fixation proximally

The position of the plate and the quality of fracture reduction is checked with the image intensifier in both AP and lateral planes. If satisfactory, a K-wire is placed through the second proximal hole for temporary plate fi xation. The plate then is fi xed at the center of the medial tibial cortex, or close to its posteromedial border, with a cortex screw used as a reduction screw. 5.2.4

Fracture reduction and distal plate fixation

In multifragmentary fractures, the fracture fragments may be viewed as pieces of a puzzle. Although anatomical reduction of the fragments is not necessary, their position relative to one another is helpful for assessing length. When the length is restored, the distal fragment is fi xed with one screw in the center or close to the posteromedial border of the medial cortex of the tibia.

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17

5

Tibia and fibula, shaft

Operative procedure

a

(cont)

b

Animation

c

d

Fig | Anim 17-8a–d a–b c d

Fracture reduction and plate fi xation. Modular external fi xator used as a reduction tool. The tubes function as handles for manipulation of the fracture fragments. The tunneler is slipped between subcutaneous layer and periosteum, preferably from distal to proximal, and pulled back with the plate tied to it. If the fracture is correctly reduced, plate fi xation will be carried out according to plan.

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5

Operative procedure

(cont)

The varus–valgus alignment is usually reduced by the plate and this can be checked by using the cable technique. A lateral view with the image intensifier is used to detect sagittal plane deformities which, if present, can be adjusted if only one screw is inserted in the distal fragment. Once the overall alignment is satisfactory, further screws are inserted spaced more widely apart. Two screws can be inserted obliquely through one incision which lies between two plate holes. One screw on each fragment should be fi xed close to the fracture and one screw at each end of the plate. Generally, two to three screws are inserted in each fragment.

5.3

Lateral approach

The two 3–4 cm skin incisions are made 1 cm lateral to the tibial crest. The fascia over the tibialis anterior muscle is incised and the muscle is gently separated from the tibia. In order to avoid injury to the deep peroneal nerve and anterior tibial artery at the distal incision, these structures should be identified and protected (Fig 17-9). The extraperiosteal tunnel is prepared by sliding the soft-tissue retractor from proximally. The plate is then inserted into the prepared tunnel using a plate holder but great care is required as the muscles can be stripped. Reduction and fi xation are done the same way as in the medial approach (Fig 17-10).

Fig 17-9a–b

Lateral approach for tibial shaft fractures. Two 3–4 cm incisions 1 cm lateral to the tibial crest. b The deep peroneal nerve and the anterior tibial vessels have to be retracted along with tibialis anterior tendon. a

a

b

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17

5

Tibia and fibula, shaft

Operative procedure

a

(cont)

b

c

Fig 17-10a–c

Plate fi xation with the lateral approach. The tunnel for plate introduction is prepared over the periosteum. b The plate on a plate holder is slipped in along the pathway prepared. c A cancellous bone screw is fi rst placed proximally in order to reduce and secure the plate. Applying manual traction, the fracture is reduced and the plate is fi xed distally. The alignment is checked and the remaining screws are inserted. a

6

Postoperative care

The patient is allowed to partially weight bear as tolerated (10–15 kg) as early as the second to fourth postoperative day depending on the general condition. AP and lateral x-rays of the tibia are taken at 6 weeks, 3 months, and 6 months to

assess healing and to look for secondary loss of alignment. The patient is allowed full weight bearing when the fracture is consolidated.

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7

Pitfalls –

8

Pearls +

Pitfall 1

Pearl 1

Malrotation is not common at the diaphyseal area of the tibia because of the flat surfaces on both medial and lateral aspects. It usually occurs in fractures of the distal third. Rotation is usually assessed clinically by comparison with the opposite leg.

The plate can be used as a reduction tool. Once the plate is attached to one fragment in the correct position, the fracture is reduced by manual traction or with a distractor to restore the length. A second cortex screw is then inserted into the other main fracture fragment to act as a reduction screw to pull the bone fragment toward the plate to achieve reduction of the fracture. However, with this technique it is important fi rst to restore the length, otherwise the bone fragments will obstruct one another due to overlapping of the fractured ends or crack during tightening of the screws, or the reducing screw thread may strip.

Pitfall 2

Pearl 2

Varus and valgus angulation is checked intraoperatively by portable x-rays or an image intensifier. Portable x-rays can be used to evaluate the axis of the tibia from the knee joint to the ankle joint in one fi lm. The image intensifier is more convenient to use intraoperatively but the entire long axis of the tibia cannot be evaluated in one view. The tibial alignment grid is a helpful tool made by mounting parallel K-wires between two plastic plates. Axis of the tibia can be evaluated by placing the grid under the tibia with the image intensifier at the knee joint; set the K-wire parallel to the joint line. Then the C-arm is positioned perpendicular to the ankle joint and an x-ray is taken at the ankle joint. When the K-wire at the ankle is parallel to the joint line it means that the knee joint and ankle joints are parallel and the coronal plane angulation of the tibia is restored (Fig 17-11a–b). By the same principle, an external fi xator with two parallel Steinmann pins spanning the knee and ankle joints can be used for evaluation of the tibial axis (Fig 17-12). Another intraoperative technique for controlling varus and valgus malalignment is by the cable technique (Chapter 10 Complications and solutions; Fig 10-6).

Shortening can be corrected by using the distractor or an external fi xator. Manual traction is successful when the fracture is acute or if there is only slight shortening. The tension device or push–pull forceps can also be used to help correct shortening (Chapter 7 Reduction techniques: Fig | Anim 7-6). It is advisable to insert the fi rst screw in the second last hole of the plate. If there is shortening, this screw is removed and further distraction is applied until the last plate hole lies over the empty hole from which the screw has just been removed. Then the screw is reinserted and this will result in a gain in length, which is the distance between two plate holes (see Chapter 14 Femur, shaft; 8 Pitfalls: Fig 14-14).

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17

7

Tibia and fibula, shaft

Pitfalls –

Pitfall 2

a

(cont)

(cont)

8

Pearls +

(cont)

Pearl 3

b

After slipping the plate into the tunnel on the lateral side, it can not only slide freely proximally and distally, but it also has a tendency to be pushed anteriorly because of the muscle mass. To keep the plate in a proper position during screw insertion, two or three K-wires may be applied through the plate holes or outside the plate to fi x the plate temporarily.

Fig 17-11a–b Varus or valgus malalignment evaluated by using a tibial alignment grid.

Fig 17-12

An external fi xator with two parallel Steinmann pins spanning the knee and ankle joint can also be used for evaluation of the tibial axis.

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7

Pitfalls –

(cont)

8

Pearls +

(cont)

Pitfall 3

Angulation in the sagittal plane can be evaluated clinically by palpation of the posteromedial tibial border or the tibial crest but soft-tissue swelling sometimes makes this method unreliable. External rotation of the tibia with the knee extended or putting the leg in a figure-of-four position to obtain a lateral view of the tibia with the image intensifier is unreliable because that is not the true lateral view. The correct lateral view is obtained by supporting the knee with a small towel and rotating the tibia internally 20°. The image intensifier is then positioned to obtain a cross-table lateral projection of the tibia. Alternatively, the image intensifier is tilted 30°–45° and the extremity externally rotated and positioned perpendicular to the C-arm.

9

Suggested reading

Gautier E, Sommer C (2003) Guidelines for the clinical application

Weller S, Höntzsch D, Frigg R (1998) [Epiperiostal, percutaneous

of the LCP. Injury; 34(2):B63–B76.

plate osteosynthesis. A new minimally invasive technique with

Helfet DL, Shonnard PY, Levine D, et al (1997) Minimally

reference to “biological osteosynthesis”] Unfallchirurgie; 101:115–121.

invasive plate osteosynthesis of distal fractures of the tibia. Injury;

German.

28(1):A42–A48. Krettek C, Miclau T, Grun O, et al (1998) Intraoperative control of axes,rotation and length in femoral and tibial fractures. Technical note. Injury; 29(3):C29–C3. Krettek C, Schandelmaier P, Miclau T, et al (1997) Minimally invasive percutaneous plate osteosynthesis (MIPPO) using the DCS in proximal and distal femoral fractures. Injury; 28(1):20–30. Mast J, Jakob R, Ganz R (1989) Planning and Reduction Techniques in Fracture Surgery. 1st ed. Berlin Heidelberg New York:Springer-Verlag. Rüedi TP, Murphy WM (2001) AO Principles of Fracture Management. Stuttgart, New York: Georg Thieme Verlag.

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Author

17.1 1

Theerachai APIVATTHAKAKUL

Tibia and fibula, shaft: wedge fracture, fragmented wedge– 42-B3 Case description

A 35-year-old male had a motorcycle accident and sustained a closed multifragmentary fracture of the tibial shaft. The fracture was unstable and needed to be immobilized in a cast.

a

2

b

Fig 17.1-1a–b

X-rays AP/lateral show the multifragmentary fracture of the tibial shaft.

Indication for MIPO

The fracture can be treated by nailing (intramedullary splint) or plating (extramedullary splint) by the principle of relative stability.

3

Patient positioning

The patient lies supine on the radiolucent operating table. Use of a tourniquet is optional, but is usually not necessary.

When plating is used, MIPO should be considered as this helps to preserve the blood supply of the fracture fragments.

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17

4

Tibia and fibula, shaft

Surgical approach

The medial approach is used as the condition of the soft tissue is good.

a

b

c

Fig 17.1-2a–c

The 14-hole narrow DCP is placed over the medial cortex of the tibial shaft to determine its correct position using the image intensifier.

Fig 17.1-3a–d a a

b

c

d

A 3 cm incision is made along posteromedial border of the tibia at the distal end of the plate. The incision is extended down to the periosteum. b An extraperiosteal tunnel is prepared with the tunneler passed from distal to proximal. c The plate is slipped into the tunnel and positioned in the center of the medial cortex of the tibia. d Fixation is carried out with one cortex screw in the distal fragment.

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17.1

5

Tibia and fibula, shaft: wedge fracture, fragmented wedge–42-B3

Reduction and fixation

a

b

Fig 17.1-4a–b a

Manual traction and fracture reduction is done to obtain correct length and rotation. b When correct length and rotation is achieved the plate is fi xed proximally with one cortex screw.

a Fig 17.1-5a–b

b

Any sagittal plane angulation is checked with a lateral view using the image intensifier.

Fig 17.1-6

Plate fi xation is carried out with three cortex screws in each fragment.

Fig 17.1-7

The surgical incisions used for the MIPO technique. 297

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17

5

Tibia and fibula, shaft

Reduction and fixation

(cont)

6

Rehabilitation

The patient was encouraged to exercise the knee and ankle from the fi rst postoperative day. Partial weight bearing of 10–15 kg was allowed, and progressive weight bearing was encouraged as more bridging callus formed.

a

b

Fig 17.1-8a–b X-rays AP/lateral postoperatively show good alignment of the fracture.

7

Pitfalls –

8

Pearls +

Pitfall

Pearl 1

Malalignment is more common compared to conventional open reduction and internal fi xation (ORIF).

Correct precontouring and correct positioning of the plate is required.

Pearl 2

Intraoperative assessment of the length, rotation, and axial alignment is essential.

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Author

17.2 1

Theerachai APIVATTHAKAKUL

Tibia and fibula, shaft: wedge fracture, fragmented wedge– 42-B3

Case description

a

b

Fig 17.2-1a–b

A 33-year-old male met with a motorcycle accident and sustained an isolated Gustilo type II open fracture (42-B3) of the shaft of the left tibia.

2

a

b

Fig 17.2-2a–b The fracture was anatomically reduced at the time of debridement and primarily stabilized with an external fi xator in sagittal plane.

Indication for MIPO

MIPO is considered a safe option in open fractures after initial wound debridement and stabilization using an external fi xator. The pro-

3

Fig 17.2-3 10 days after injury, the wound condition was satisfactory, and the bony alignment was good. Defi nitive treatment by MIPO technique was undertaken with the external fi xator left in place to stabilize the fracture reduction during MIPO.

Patient positioning

The patient lies supine on the radiolucent operating table. The tourniquet is not used in this case.

cedure is also easy to carry out especially if the fracture has been well reduced and the reduction maintained with an external fi xator. The plate is applied on the lateral surface of the tibia because of better soft-tissue coverage.

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17

4

Tibia and fibula, shaft

Surgical approach

a Fig 17.2-4 A 12-hole narrow DCP is used as a template for marking the skin incisions.

b

Fig 17.2-5a–d a

A proximal incision of 3 cm is made 1 cm lateral to the tibial crest with deep dissection between the tibia and the tibialis anterior muscle. b A tunneler is slipped over the periosteum from proximal to distal.

c

d

c

A distal incision of 3 cm is made 1 cm lateral to the tibial crest. The anterior tibial vessels, deep peroneal nerve, and tibialis anterior muscle are retracted laterally. d The tunneler is slipped from distal to proximal to prepare the tunnel for the plate.

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17.2

5

Tibia and fibula, shaft: wedge fracture, fragmented wedge–42-B3

Reduction and fixation

a

b

Fig 17.2-6a–b a b

The plate is slipped into the tunnel from proximal to distal. The plate is positioned in the center of the tibia proximally and distally.

a Fig 17.2-7a–b

each.

b

Distal and proximal fragments are fi xed with three cortex screws

Fig 17.2-8 Sutured skin incisions with the external fi xator still in place.

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17

5

Tibia and fibula, shaft

Reduction and fixation

(cont)

a Fig 17.2-9

The external fi xator is removed when plate fi xation is completed.

6

Fig 17.2-10a–b

b

Postoperative x-rays AP/

lateral.

Rehabilitation

The patient started ambulation with partial weight bearing and range of motion exercises for the ankle and knee.

a

b

Fig 17.2-11a–b X-rays after 6 months show complete fracture consolidation.

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18

Tibia and fibula, distal

1

Introduction

305

Cases

1.1 1.2

Classification

305

18.1

Indications and contraindications for MIPO

306

2

Surgical anatomy

306

3

Preoperative assessment

307

3.1

History and clinical examination

307

3.2

X-ray examination

307

4

Timing of surgery

307

5

Preoperative planning

308

6

OR set-up

310

6.1

Anesthesia

310

6.2

Patient positioning and image intensifier

310

6.3

Choice of implants

310

6.4

Instruments

310

7

Operative procedure

311

7.1

Fixation of the fibular fracture

311

7.2

Fixation of the tibial fracture

311

8

Postoperative care and rehabilitation

314

9

Pitfalls

314

10

Pearls

314

11

Suggested reading

316

Tibia and fibula, distal: extraarticular fracture, simple—43-A1

18.2

317

Tibia and fibula, distal: complete articular fracture, articular simple, metaphyseal, multifragmentary—43-C2

321

Teaching video on DVD-ROM 18

Tibia, distal—medial approach

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Authors

18

1

Young-Soo BYUN, Chang-Wug OH

Tibia and fibula, distal

Introduction

The best results for displaced articular fractures of the distal tibia have been achieved by reconstruction of the articular surface of the tibia, stable fi xation, and early rehabilitation. However, conventional operative treatment of such injuries results in extensive soft-tissue dissection and periosteal stripping which is associated with high rates of wound dehiscence and infection, delayed union, and nonunion. Minimally invasive plate osteosynthesis (MIPO) has evolved in response to the disappointing results following traditional methods of surgical stabilization of these distal tibial fractures.

a

b

c

Fig 18-1a–c

43-A extraarticular fracture. a 43-A1 simple b 43-A2 wedge c 43-A3 complex

MIPO offers biological advantages by minimizing softtissue compromise and maintaining vascular integrity of the fracture fragments as well as preserving the osteogenic fracture hematoma. 1.1

Classification

Classification of distal tibial fractures is important in determining their prognosis and choosing the appropriate treatment. Fractures of the distal tibia occur with or without involvement of the articular surface of the ankle joint. According to the Müller AO Classification, fractures of the distal tibia are divided into three groups: 43-A extraarticular fracture, 43-B partial articular fracture, and 43-C complete articular fracture (Fig 18-1, Fig 18-2, Fig 18-3). 1.2

a

b

c

Fig 18-2a–c

43-B partial articular fracture. 43-B1 pure split b 43-B2 split-depression c 43-B3 multifragmentary depression a

Indications and contraindications for MIPO

Simple fractures of the distal tibia with minimal displacement may be treated successfully with nonoperative methods.

a

b

c

Fig 18-3a–c

Complex fractures of the distal tibia almost always require surgical management and the soft-tissue condition usually determines the timing and choice of the procedure.

43-C complete articular fracture. a 43-C1 articular simple, metaphyseal simple b 43-C2 articular simple, metaphyseal multifragmentary c 43-C3 articular multifragmentary 305

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1

Introduction

(cont)

Indications for MIPO in fractures of the distal tibia are intraarticular or periarticular fractures with or without proximal extension of the fracture into the distal diaphysis and which are considered unsuitable for intramedullary nailing. They include low-grade open fractures of the distal tibia, displaced pilon fractures with sufficient medial soft-tissue coverage to allow articular reconstruction and percutaneous plating, and unstable distal metaphyseal and diaphyseal fractures.

2

MIPO is contraindicated in situations where the medial soft tissue is compromised, such as in severe open fractures or badly contused skin. If the bone is osteoporotic or comminution is so excessive that surgery cannot restore or stabilize the joint, then other methods of treatment must be sought. In severely shattered pilon fractures, the only solution may be fi rst application of a spanning external fi xator, followed later by secondary arthrodesis of the ankle joint.

Surgical anatomy

The condition of the skin and subcutaneous tissues surrounding the distal tibia is of extreme importance. Since the anteromedial surface of the distal tibia is only covered by skin and subcutaneous tissues, lacking the protection of muscles, there may be trauma caused by the fracture fragments from within. The resultant massive swelling may lead to the formation of fracture bullae, and skin necrosis may ensue.

The thick-walled, triangular-shaped diaphysis of the tibia flares distally at the transition from the diaphysis to the metaphysis. At the distal tibial metaphysis, the cortex is thin and the metaphysis is fi lled with relatively dense cancellous bone. The medial aspect of the distal tibia has approximately 25º of medial angulation and 20º of internal torsion (Chapter 17 Tibia and fibula, shaft: Fig 17-4).

The ankle joint is formed by the distal ends of the tibia and fibula as well as the talus, including the joint capsule and ligaments. Any incongruity of the articular surface or an unduly broad ankle mortise will lead to local overload, frequently resulting in cartilage degeneration and post-traumatic osteoarthritis. The distal fibula is held in the notch of the tibia by the interosseous membrane and the anterior and posterior tibiofibular ligaments. In intraarticular pilon fractures involving both bones, the syndesmotic ligaments are usually intact, but may sometimes be avulsed from the tibia together with bony fragments. The talofibular ligaments may be torn, especially in the type of varus injury where the fibula remains intact. The deltoid ligaments are nearly always intact, permitting indirect reduction by ligamentotaxis in selected cases.

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18

3

Tibia and fibula, distal

Preoperative assessment

Assessment of patients should be thorough and systematic to ensure full evaluation and injuries to other parts of the body should not be overlooked, treating the patient as a whole. The character of the injury is determined by careful assessment of the patient, injury, and environment. 3.1

History and clinical examination

The mechanism of injury usually determines the extent of skeletal and soft-tissue injury. Low-energy trauma usually leads to simpler fracture patterns with minimal soft-tissue injury, while high-energy trauma with axial compression produces complex intraarticular fractures with metaphyseal impaction and is frequently associated with an open wound or severe soft-tissue injury. The extremity should be examined carefully. Considerable swelling of the foot and ankle often develops shortly after injury. Fracture blisters are a sign of massive soft-tissue swelling and should be a warning against any immediate surgical intervention.

Assessment of the neurovascular status of the limb must also be precise and documented, particularly for the sensory distribution of the superficial and deep peroneal nerves because these nerves are at increased risk of injury. Special attention has to be given to early signs of compartment syndrome, even though this is rather unusual. Open wounds are inspected to determine their extent and the amount of contamination. 3.2

X-ray examination

Standard AP and lateral x-rays are needed, but in complex fractures, more information about the tibiotalar joint is necessary. Traction x-rays provide more information about the fracture pattern and demonstrate the extent to which the articular surface can be reduced by ligamentotaxis. CT scan with 3-D reconstruction helps to defi ne the severity of the injury. Axial cuts of the CT scan delineate the size and orientation of the articular fragments. This information is crucial for decision making and preoperative planning, especially when the minimally invasive approach to articular reduction is being considered. MRI studies are rarely required at the early stage, but they may later provide information about vascularity of the bone and vitality of the cartilage.

Grossly displaced fractures or dislocations must be reduced immediately to minimize further soft-tissue compromise.

4

Timing of surgery

Only simple fractures of the distal tibia with minimal softtissue injury may be defi nitively stabilized within the fi rst 6–8 hours. However, most patients are seen later than this, and by then, the skin and soft tissue are often not suitable for immediate surgery. For these patients, surgery should be delayed for 5–7 days until the soft-tissue edema has subsided and the skin begins to wrinkle. In the meantime, the fracture is usually immobilized by joint bridging external fi xation or calcaneal traction.

The best time for surgery is determined by the condition of the skin and soft tissue.

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5

Preoperative planning

Prior to surgery, careful preoperative planning is an essential part of the treatment of distal tibial fractures. It consists of careful study of x-rays, drawings of fracture fragments and the desired end result, reduction techniques, and choice of implants. For preoperative drawings, AP and lateral x-rays of good quality are required of both the injured and the normal side. A tracing is made of the normal side, and the fracture is drawn on another sheet. The fracture fragments may be drawn separately or cut out, and then reassembled on the drawing of the

a

b

c

normal side which has been reversed to match the fractured side. Finally, with the use of transparent templates, the appropriate implants are drawn on the reconstructed distal tibia and fibula. For stabilization of articular fragments, small fragment screws, 3.5 and 4.0 mm standard or cannulated screws, are commonly selected and drawn onto the appropriate sites, depending on the position of articular fragments. By overlaying the templates, the surgeon can determine the optimal type and length of the implants to be used, the number and type of screws required, their sequence of insertion, and thus defi ne the step-by-step sequence of the procedure (Fig 18-4).

d

Fig 18-4a–h

Preoperative drawing; overlay using the normal side. The initial x-rays show a type 43-A3 fracture of the distal tibia associated with a fibular fracture. c–d The intact side is drawn as a template for the fractured limb. 3-D CT image shows the fracture pattern from the posterior aspect of the distal tibia. a–b

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18

5

Tibia and fibula, distal

Preoperative planning

(cont)

6 2

3

4 1 5 e

f

Fig 18-4a–h e f

g

h

(cont)

Fixation of the fibular fracture with a one-third tubular plate and lag screw fi xation for the oblique fracture. A distal tibia LCP is inserted through a small incision at posteromedial aspect of the medial malleolus. A preliminary K-wire is inserted through the most distal hole of the plate to check the level of the ankle joint. A cortex screw is inserted through the second most distal hole; this functions as reduction tool to stabilize the plate to the bone.

g

Manual traction is applied and a cortex screw is inserted proximally through the oval hole to reduce and hold the fracture. The reduction is checked with an image intensifier. h If fracture reduction is satisfactory, the fi xation is completed in sequence (3–6) with locking head screws (LHS). The cortex screws (1, 2) may be changed to LHS if necessary.

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6

OR set-up

6.1

Anesthesia

The patient should be operated under general or regional anesthesia. 6.2

The cloverleaf plate or the newer cloverleaf LCP is a good choice, especially for intraarticular fractures or extraarticular fractures with a short distal fragment.

Patient positioning and image intensifier

For MIPO procedures, the patient is placed supine on a radiolucent operating table with a support under the knee (Fig 18-5). The use of a tourniquet is optional, but should be avoided if possible. The image intensifier is positioned on the side of the operating table opposite to the injured extremity. 6.3

For extraarticular fractures of the distal tibia, the narrow DCP 4.5, LC-DCP 4.5, LCP 4.5/5.0, or T-plate is usually selected, but they have limitations in fi xation of the small distal fragment.

Choice of implants

For fibular fractures, the standard implant is the one-third tubular plate. The stronger LC-DCP 3.5 or LCP 3.5 can be used for complex fibular fractures. The intramedullary pin may be a useful option in the rare situation of severe lateral soft-tissue damage or in some cases of transverse fractures.

The newly developed metaphyseal LCP may be a good option for both extraarticular fractures with a short distal fragment as well as intraarticular fractures. Small fragment screws such as 3.5 and 4.0 mm standard or cannulated screws are commonly used to stabilize the articular fragments of the distal tibia. The length of the plate depends on the fracture pattern and the mechanical concept used for fi xation. The plate length can be increased without additional soft-tissue dissection in the MIPO technique. Before fi xation, the selected plate must be contoured to fit exactly the medial surface of the distal tibia using a dry bone or a bone model to prevent malalignment. However, when using the LCP as an internal fi xator, the exact adaptation of the implant to the bony surface is not mandatory. 6.4

Instruments

Pointed reduction forceps or a collinear reduction clamp may be useful to reduce the articular or metaphyseal fracture percutaneously. K-wires are usually used for preliminary fi xation of the articular fragments. K-wires or Schanz screws, used as joysticks, are helpful to correct any residual angular deformity. A large Kelly clamp or a special tunneling instrument is used to create a subcutaneous tunnel.

Fig 18-5

The patient lies in a supine position with a support under the knee. The tourniquet is optional.

A large distractor or external fi xator may be helpful for obtaining indirect fracture reduction and temporarily maintaining the reduction in complex cases.

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18

7 7.1

Tibia and fibula, distal

Operative procedure Fixation of the fibular fracture Accurate reduction and stabilization of the fibular fracture is an essential part of the treatment, especially for intraarticular pilon fractures.

Usually fi xation of the fibular fracture is carried out fi rst. The incisions for the fibular and tibial fractures should be at least 5–7 cm apart (Fig 18-6a). Simple or wedge fractures of the fibula are usually approached by a straight or slightly curved incision posterior to the fibular crest for direct reduction with pointed reduction forceps and stabilization by a one-third tubular plate in a lateral or posterior antiglide position. Complex fractures of the fibula can be reduced indirectly by the push–pull technique or with a small distractor. After restoring the correct length and alignment, the fracture is usually fi xed with the stronger LC-DCP 3.5 or LCP 3.5 using the MIPO technique through two small incisions proximal and distal to the fracture. In the rare situation of severe lateral soft-tissue damage or in some cases of transverse fractures, the fibula may be fi xed with an intramedullary pin through a small incision at the tip of the lateral malleolus, but the intramedullary pin does not control rotation. Fibula fi xation is helpful in reduction of the distal tibial fracture and also adds more stability to tibial fi xation. 7.2

Fixation of the tibial fracture

In complex cases with articular comminution and metaphyseal impaction, joint-bridging distraction with a large distractor or external fi xator may be helpful to obtain preliminary indirect fracture reduction to restore limb length and axis.

The articular surface should be anatomically reduced percutaneously by indirect reduction, using the image intensifier and pointed reduction forceps, or by direct open reduction through a small anteromedial incision and a vertical arthrotomy.

The articular fragments are held in position with pointed reduction forceps and temporary K-wires. A cancellous bone graft may be needed to support the reduced articular fragments in their anatomical position. The bone graft should be fully impacted into the metaphyseal defect in order to restore stability to the distal fragment. After checking the reduction by image intensifier, the articular fragments are stabilized with cancellous bone screws or cannulated screws used as lag screws. The metaphyseal fracture, with or without proximal extension into the distal tibial diaphysis, is reduced by indirect reduction techniques.

Pointed reduction forceps or a collinear reduction clamp may be useful to reduce the metaphyseal fracture percutaneously. Using an anteromedial approach, a 2–3 cm incision is made starting at the level of the tibial plafond and extending proximally along the medial surface of the distal tibia. Alternatively, a posteromedial incision along the posterior border of medial malleolus about 4–5 cm in length and slightly curved can be used (Fig 18-6b). A subcutaneous tunnel is created along the medial aspect of the tibia by blunt dissection using a large Kelly clamp or a special tunneling instrument, and the preselected and precontoured plate is advanced beneath the soft tissue through the tunnel. On occasion, the plate may be inserted directly beneath the subcutaneous tissue without fi rst making a tunnel. A small incision is made at the proximal end of the plate. The plate should be placed parallel to the posterior border of the distal tibia and the position of the plate is checked

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7

Operative procedure

(cont)

using the image intensifier in the AP and lateral planes. The distal end of the plate should be at the level of the tibial plafond and the proximal end should extend at least three screw holes beyond the proximal extent of the fracture. The plate is then fi xed temporarily either with K-wires or with cortex screws at the most distal and proximal plate holes. If an LCP is used, one locking head screw (LHS) is inserted in the metaphyseal fragment at the distal part of the plate close to the joint line and another is inserted at the other plate end. Reduction is then checked with the image intensifier in both planes. Any residual angular deformity of the metaphyseal fracture in the coronal or sagittal plane can be corrected by a K-wire or a Schanz screw used as a joystick or by the use of pointed reduction forceps or a collinear reduction clamp applied percutaneously. Varus malalignment can also be reduced by the insertion of a cortex screw near the fracture to pull the bone toward the plate. If an LCP is used, it may be necessary to temporarily loosen the LHS in order to do this.

a

Limb rotation can be checked by the range and symmetry of the foot rotation as well as comparing the position of both feet with the knees in flexion and the feet in dorsiflexion. Rotation can also be assessed by image intensifier, comparing the shape of the proximal and distal tibiofibular joints and the position of the patella with the contralateral side (Fig 18-7). The intact side can be used as a reference for the injured limb after preliminary fi xation. b Fig 18-6a–b Incisions used for fractures of the distal tibia and fibula. a Long lateral incision along posterior border of the fibula for direct reduction technique. b Medial incision along the posterior border of medial malleolus about 4–5 cm in length and slightly curved.

The fi xation is completed with insertion of the appropriate screws in the midsection of the plate through small stab incisions. The type of screw used depends on the bone quality and fracture pattern. For safety reasons, a minimum of three screws is recommended on each side of the fracture. The overall alignment of the extremity, joint congruency, and position of the implants are confi rmed by x-rays or with the image intensifier.

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18

7

Tibia and fibula, distal

Operative procedure

a

(cont)

b

c

d

Fig 18-7a–d

Radiological assessment of rotation. a The shape of the tibiofibular joints and the position of the patella on the intact side. b Correct rotational alignment in the fractured limb: The shape of the tibiofibular joint and the position of the patella are the same as those of the intact opposite side.

c

Internal malrotation: The tibia and fibula in the proximal tibiofibular joint are more overlapped and the patella is displaced laterally. d External malrotation: The tibia and fibula in the proximal tibiofibular joint are less overlapped and the patella is displaced medially.

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8

Postoperative care and rehabilitation

Postoperatively, a below-knee plaster splint is usually applied with the ankle in a neutral position to prevent an equinus deformity. The leg is elevated to reduce swelling. Physiotherapy is started immediately after subsidence of postoperative acute pain. The majority of patients are encouraged to toetouch partial weight bearing (10–15 kg) as soon as the swelling

9

Pitfalls –

is reduced, depending on the stability of fi xation and reconstruction of the fracture. X-rays are taken at 2 weeks and then at 4-weekly intervals to assess healing and alignment. Patients are progressed to full weight bearing depending on radiological fracture consolidation, usually after 8–10 weeks, but not before there is radiological evidence of callus formation.

10

Pearls +

Pitfall 1

Pearl 1

Soft-tissue compromise and infection with wound disruption after operative treatment of distal tibial fractures are the most serious complications and a difficult challenge to manage. Poor handling of the soft tissue during surgery also increases the risks of wound breakdown and infection.

Careful preoperative planning and gentle handling of the skin and soft tissue are the keys to successful surgery. Be wary of operating on elderly patients with peripheral vascular disease or diabetes mellitus.

Pitfall 2

Pearl 2

Early operation through severely traumatized soft tissue with fracture blisters often leads to soft-tissue problems of skin necrosis and/or infection.

In the presence of severe soft-tissue swelling or skin blisters, it is advisable to delay surgery for about a week until the swelling has subsided and the skin begins to wrinkle. A joint bridging external fi xator may be applied in the meantime to immobilize the fractures.

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18

9

Tibia and fibula, distal

Pitfalls –

(cont)

10

Pearls +

(cont)

Pitfall 3

Pearl 3

As the MIPO technique does not allow direct visualization of the fracture during the surgical procedure, and alignment is assessed by the image intensifier, axial malalignment can occur.

Malalignment and shortening can be avoided by accurate reduction and fi xation of the fibular fracture, if present, as a fi rst step; accurate precontouring of the tibial plate, especially when conventional nonlocking plates or standard screws are used; and familiarity with the various methods of assessing limb length and alignment intraoperatively.

Pitfall 4

Pearl 4

When an impacted articular fracture is reduced, a residual metaphyseal defect is usually left. Failure to fi ll this with bone graft may lead to collapse and loss of reduction.

Whenever present, metaphyseal defects should be impacted with autogenous bone graft or bone substitute to support the reduced articular fragments. In anticipation of this, it is always prudent to obtain consent from the patient for bone grafting and the donor site prepared before starting the operation.

Pitfall 5

Pearl 5

Too early weight bearing or poor patient compliance may lead to implant loosening with resultant deformity and delayed union or nonunion.

Postoperatively, the patient should be monitored closely. The amount of weight bearing permitted is based on the progression of fracture healing and patient compliance. Bone grafting may be indicated if there is no sign of fracture healing within the expected time frame.

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11

Suggested reading

Arens S, Kraft C, Schlegel U, et al (1999) Susceptibility to local infection in biological internal fi xation. Experimental study of open vs minimally invasive plate osteosynthesis in rabbits. Arch Orthop Trauma Surg; 119:82–85. Collinge CA, Sanders RW (2000) Percutaneous plating in the lower extremity. J Am Acad Orthop Surg; 8:211–216. Helfet DL, Shonnard PY, Levine D, et al (1997) Minimally invasive plate osteosynthesis of distal fractures of the tibia. Injury; 28(1):A42–A48. Helfet DL, Suk M (2004) Minimally invasive percutaneous plate osteosynthesis of fractures of the distal tibia. Instr Course Lect; 53:471–475. Mast J, Jakob R, Ganz R (1989) Planning and Reduction Techniques in Fracture Surgery. 1st ed. Berlin Heidelberg New York:Springer-Verlag. McFerran MA, Smith SW, Boulas HJ, et al (1992) Complications encountered in the treatment of pilon fractures. J Orthop Trauma; 6:195–200. Oh CW, Kyung HS, Park IH, et al (2003) Distal tibia metaphyseal fractures treated by percutaneous plate osteosynthesis. Clin Orthop Relat Res; 408:286–291. Resch H, Benedetto KP, Pechlaner S (1986) [Development of posttraumatic arthrosis following pilon tibial fractures.] Unfallchirurg; 89:8–15. German. Rüedi TP, Allgöwer M (1979) The operative treatment of intraarticular fractures of the lower end of the tibia. Clin Orthop Relat Res; 138:105–110. Rüedi TP, Murphy WM (2001) AO Principles of Fracture Management. Stuttgart New York: Georg Thieme Verlag.

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Authors

18.1 1

Young-Soo BYUN, Chang-Wug OH

Tibia and fibula, distal: extraarticular fracture, simple—43-A1

Case description

A 33-year-old male sustained a 43-A1 fracture of the distal tibia in a sports injury. The fracture was immobilized temporarily in a below-knee plaster splint. MIPO for the distal tibial fracture was performed 4 days after injury.

a

2

b

Fig 18.1-1a–b

Initial x-rays show a 43-A1 extraarticular, simple fracture of the

distal tibia.

Indication for MIPO

The unstable fracture of the distal tibial metaphysis is a good indication for plate fi xation as the fracture is present at the distal metaphysis and the short distal fragment and wide medullary canal make it unsuitable for intramedullary nailing. MIPO is preferred to traditional open reduction technique as the latter often requires

3

Patient positioning

The operation is carried out under general anesthesia. The patient is placed supine on the radiolucent operating table. The leg is placed on a pad and a pneumatic tourniquet is applied to the proximal thigh. The image intensifier is positioned on the side of the operating table opposite to the injured extremity.

extensive dissection and may result in soft-tissue compromise and infection with wound disruption.

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18

4

Tibia and fibula, distal

Surgical approach

Fig 18.1-2a–b a

a

5

The fracture is reduced preliminarily by manual traction and use of pointed reduction forceps percutaneously. Adequate reduction of the fracture is confi rmed using an image intensifier. b A small longitudinal incision for plate insertion is made from the level of the tibial plafond and extended proximally along the posteromedial border of the distal tibia.

b

Reduction and fixation

a

b

Fig 18.1-3a–h a–b A premeasured and precontoured metaphyseal LCP is

c

d

inserted, using the threaded drill guide as a handle, into a subcutaneous tunnel and the fracture is reduced. c–d The position of the plate is adjusted under fluoroscopic guidance.

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18.1

5

Tibia and fibula, distal: extraarticular fracture, simple—43-A1

Reduction and fixation

e

(cont)

f

g

Fig 18.1-3a–h

(cont)

e–g The fi rst screw is inserted at the distal end of the plate close to the joint line

h

a

h

b

and the second screw is inserted percutaneously at the proximal end of the plate. After confi rming fracture reduction using an image intensifier, a lag screw is inserted through the plate to reduce the fracture gap. Locking head screws are inserted percutaneously in the midsection of the plate. MIPO technique requires only small incisions.

Fig 18.1-4a–b

Postoperative x-rays show satisfactory reduction and stable fi xation of the distal tibial fracture with a metaphyseal LCP. 319

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18

6

Tibia and fibula, distal

Rehabilitation

Fig 18.1-5

Postoperatively, a below-knee plaster splint was applied with the ankle in a neutral position to prevent an equinus position. Physiotherapy was started on the third postoperative day with active assisted exercises of the ankle. Toe-touch partial weight bearing (10–15 kg) was allowed from 3 weeks postoperatively and full weight bearing after formation of visible callus 12 weeks postoperatively.

a

b

Fig 18.1-6a–b

Follow-up x-rays 6 months after surgery show good fracture alignment and healing with external callus.

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Authors

18.2 1

Young-Soo BYUN, Chang-Wug OH

Tibia and fibula, distal: complete articular fracture, articular simple, metaphyseal multifragmentary—43-C2

Case description

A 56-year-old female fell while walking downhill and sustained a 43-C2 fracture of the distal tibia. The fracture was initially immobilized temporarily in a below-knee plaster splint. MIPO for the distal tibial fracture was delayed for 10 days after the injury because of soft-tissue swelling.

a

2

b

Fig 18.2-1a–b

Initial x-rays show a 43-C2 articular simple, metaphyseal multifragmentary fracture of the distal tibia.

Indication for MIPO

Because of the intraarticular involvement, intramedullary nail fi xation was deemed not suitable for this fracture. MIPO was selected as the treatment choice as it caused the least disruption of the softtissue envelope and thus reduced the chances of soft-tissue compli-

3

Patient positioning

The operation was performed under spinal anesthesia. The patient placed supine on a radiolucent operating table. A pneumatic tourniquet was applied to the thigh and the leg placed on a pad.

cations and wound breakdown.

An image intensifier was positioned on the opposite side of the operated leg.

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18

4

Tibia and fibula, distal

Surgical approach

Fig 18.2-2a–b a

a

5

a

b

Indirect fracture reduction by manual traction. b Incision for plate insertion beginning at the level of the tibial plafond and extending proximally along the posteromedial border of the distal tibia.

Reduction and fixation

b

c

Fig 18.2-3a–f a

d

Reduction of articular fracture and temporary fi xation with a K-wire followed by defi nitive fi xation using a partially threaded cancellous bone screw as a lag screw. b–c Introduction of the precontoured metaphyseal LCP into the subcutaneous tunnel using the threaded drill sleeve to hold the plate. d The position of the plate is checked and the distal part of the plate fi xed to the tibia with fully threaded cancellous bone screws.

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18.2

5

Tibia and fibula, distal: complete articular fracture, articular simple, metaphyseal multifragmentary—43-C2

Reduction and fixation

(cont)

Fig 18.2-3a–f e–f

e

f

(cont)

A cortex screw is used as a reduction screw to fi x the fracture fragment to the plate. After confi rming that fracture reduction is satisfactory using an image intensifier, the remaining screws are inserted percutaneously in the midsection of the plate.

Fig 18.2-4a–b a

b

Postoperative x-rays show restoration of anatomical alignment and stable fi xation of the distal tibial fracture with a metaphyseal LCP.

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18

6

Tibia and fibula, distal

Rehabilitation

A below-knee splint was applied postoperatively to prevent an equinus deformity. The splint was removed periodically to allow active assisted ankle exercises. Nonweight bearing walking was started on the third postoperative day and partial weight bearing permitted after 3 weeks. Full weight bearing was started 12 weeks postoperatively when visible callus bridging the fracture was noted.

a

b

Fig 18.2-5a–b Follow-up x-rays 5 months after surgery show that the fracture has healed in good alignment.

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18.2

Tibia and fibula, distal: complete articular fracture, articular simple, metaphyseal multifragmentary—43-C2

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19

Clavicle

1

Introduction

327

Cases

1.1

Classification

327

19.1

1.2

Incidence

327

1.3

Current methods of treatment

327

1.4

Indications and contraindications for MIPO

328

2

Surgical anatomy

329

3

Preoperative assessment

330

4

OR set-up

330

4.1

Anesthesia

330

4.2

Patient positioning and image intensifier

330

4.3

Instruments and implants

330

4.4

Templating and plate contouring

332

5

Operative procedure

332

5.1

Surgical approach

332

5.2

Reduction techniques

332

5.3

Plate and screw insertion

334

5.4

Step-by-step operative procedure

334

6

Postoperative care and rehabilitation

337

7

Pitfalls

337

8

Pearls

337

9

Suggested reading

338

Clavicle, shaft: spiral wedge fracture— OTA 15-B1

19.2

Clavicle, shaft: simple transverse fracture— OTA 15-A3

19.3

347

Clavicle, shaft: simple oblique fracture— OTA 15-A2 with marked displacement

19.4

339

353

Clavicle, shaft: simple transverse fracture— OTA 15-A3

357

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Author

19

1

Vajara PHIPHOBMONGKOL

Clavicle

Introduction

The majority of fractures of the clavicle can be treated conservatively with satisfactory results. Surgery is rarely required but, when indicated, should be performed carefully as internal fi xation of clavicular fractures is associated with a significant complication rate. Complications include neurovascular injury, infection, nonunion, unsightly scars, and subcutaneous prominence of the implants. Prominent implants need removal, necessitating a second operation with the possible risk of refracture after plate removal. Some of these complications may be avoided by minimally invasive plate osteosynthesis (MIPO) which, because it requires less soft-tissue dissection, may help to preserve biology thus leading to a higher healing rate and to a lower rate of infection. 1.1

c

Fig 19-1a–c

15-A Clavicle, diaphysis, simple. 15-A1 spiral b 15-A2 oblique c 15-A3 transverse a

a

b

c

Fig 19-2a–c

15-B Clavicle, diaphysis, wedge. a 15-B1 spiral wedge b 15-B2 bending wedge c 15-B3 fragmented wedge

Incidence

Fractures of the clavicle are common and occur most frequently in the middle third of the bone (76–82%) and less often in the lateral (12–21%) or medial (3–6%) third. The commonest causes of injury are sports activities and motor vehicle accidents. 1.3

b

Classification

The clavicle is assigned the number 06 according to the OTA classification. There are three types of clavicle shaft fracture: simple (15-A), wedge (15-B), and complex (15-C). Closed and open fractures should be distinguished (Fig 19-1, Fig 19-2, Fig 19-3). 1.2

a

Current methods of treatment

a

b

c

Fig 19-3a–c

15-C Clavicle, diaphysis, complex. 15-C1 spiral b 15-C2 segmental c 15-C3 irregular a

The vast majority of clavicular fractures heal with conservative treatment which consists usually of an arm sling or

327

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1

Introduction

(cont)

figure-of-eight strapping for 4–6 weeks. Some degree of malunion may result but these are often minor and are well tolerated with little compromise to overall function. Accepted indications for primary stabilization of clavicular fractures are: Open fractures Associated neurovascular injury Tenting of the skin with impending penetration by a sharp bony spike Associated with ipsilateral fractures of the scapular neck or proximal humerus resulting in instability Widely separated fractures especially those with comminution There are many implants available for fi xation of clavicular fractures, including: Different types of intramedullary pins DCP or LC-DCP 3.5 Reconstruction plate 3.5 LCP 3.5 LCP reconstruction plate 3.5

The LCP reconstruction plate 3.5 has all the advantages of the reconstruction plate 3.5, plus the added advantage of the locking mechanism which imparts angular stability thus making it more suitable for use in osteoporotic bones. Unlike the application of LCP in other locations, when used in the clavicle, accurate contouring of the plate is recommended in order to reduce the prominence of the implant subcutaneously. Another measure to reduce plate prominence is to use standard cortex screws to press the plate against the bone before applying the locking head screws (LHS). 1.4

Indications and contraindications for MIPO

While there are no defi nite indications for MIPO of fractures of the clavicle, suitable cases for the MIPO technique include recent, widely displaced, comminuted fractures of the middle third. MIPO should not be attempted in the presence of heavy wound contamination or infection, neurovascular injuries, or nonunions.

The reconstruction plate 3.5 is particularly suitable for use in clavicular fractures because it allows for accurate contouring which is an important requirement in the clavicle due to its peculiar curved anatomy. It can be applied to either its superior or anterior surface. Anterior placement of the plate allows the use of longer screws, but carries a higher risk of injury to the brachial plexus although the risk of vascular injury is significantly reduced.

328

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19

2

Clavicle

Surgical anatomy

The clavicle lies directly under the skin throughout its length. It is an S-shaped bone, concave anteriorly at its lateral end and convex anteriorly at its medial end. The cross-sectional anatomy along its lateral to medial course changes from flat to tubular to prismatic. The junction from the flat region to the tubular region is a stress riser and this explains the high incidence of midshaft fractures (Fig 19-4).

In the middle third or the tubular portion the subclavius muscle and fascia protect the neurovascular structures from the fracture. However, to avoid injury to the neurovascular structures care should be exercised when sharp instruments are used in this area.

Plates can be applied over the superior surface or anterior surface of the clavicle after appropriate contouring. The sternocleidomastoid muscle, which inserts on the medial third of the clavicle, acts as a deforming force, pulling the medial fragment superiorly, following a fracture (Fig 19-5). Pushing of the shoulder upward helps to reduce the lateral fragment to the medial fragment. The neurovascular structures, namely, the subclavian artery and vein and the brachial plexus, pass from a posterosuperior to posteroinferior direction, between the fi rst rib and the clavicle at the junction of its medial and middle thirds and are thus vulnerable during surgery and instrumentation in this region (Fig 19-6).

a Fig 19-4a–c

b

c

Different views of the anatomy of the clavicle.

Fig 19-5 The sternocleidomastoid muscle pulls the medial aspect of the clavicle superiorly after a clavicular fracture.

Fig 19-6

Neurovascular structures pass in a posterosuperior– posteroinferior direction, between the fi rst rib and the clavicle. Sharp surgical tools should be avoided in this region. 329

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3

Preoperative assessment

Preoperatively, the general condition of the patient should be assessed. The condition of the skin and soft tissue as well as the neurovascular status of the upper limb should be evaluated. Associated injuries and fractures elsewhere in the body should be taken note of. Radiological assessment includes AP and lordotic (45° upward projection) views of the clavicle which are useful for assessing the displacement and configuration of the fracture (Fig 19-7). A scapular Y-view is taken to determine the relationship between the acromion/coracoid and the scapula. A chest x-ray should also be included.

a

b Fig 19-7a–b

4

OR set-up

4.1

Anesthesia

General anesthesia is recommended. 4.2

Patient positioning and image intensifier

The patient is operated on a radiolucent operating table, in a supine or beach-chair position, depending on the surgeon’s preference (Fig 19-8a–b). The image intensifier is positioned to take AP and oblique (45° upward tilting of the tube) views of the clavicle (Fig 19-8c–d).

4.3

X-rays: AP and 45º upward projection.

Instruments and implants

The instruments helpful in MIPO of clavicular fractures include: The small external fi xator set and its instruments Pointed reduction clamps or towel clips Bone hooks Small Hohmann retractors Self-retaining retractors Instrument set for plate and screw fi xation Bending pliers Color marker As mentioned above, the reconstruction plate 3.5 or LCP reconstruction plate 3.5 are the preferred implants for clavicular fractures. Both types of plate require contouring.

330

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19

4

Clavicle

OR set-up

(cont)

a

b

c

d

Fig 19-8a–d

Patient positioning Supine (a) or beach-chair (b) position, depending on the surgeon’s preference. c–d C-arm is positioned for AP (c) and oblique (d) views. a–b

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4 4.4

OR set-up

(cont)

Templating and plate contouring

Templating is essential to select the appropriate length and location of the plate (Fig 19-9a). In the superior plate application for a midshaft fracture, the plate must be bent in a horizontal S-shaped fashion (Fig 19-9b) while in the anterior plate application, the plate must be contoured in a vertical S-shape to fit the anterior surface of the clavicle (Fig 19-9c).

a

Fig 19-9a–c a

b

5 5.1

Templating is essential to determine plate location and plate length. b Plate contouring for superior plating. c Plate contouring for anterior plating.

c

Operative procedure Surgical approach

Two skin incisions, each 2–3 cm in length, are made over the lateral and medial ends of the clavicle corresponding in position to the ends of the preselected plate.

5.2

Reduction techniques

In MIPO of clavicular fractures, the following indirect reduction techniques are useful. Shoulder manipulation

Stab wounds are made for insertion of screws, as well as for pins and pointed reduction forceps or towel clips. The stab wounds for the screws are made directly over the plate holes which can usually be palpated through the skin.

Shoulder manipulation helps to reduce the clavicular fracture. This is done with the help of the image intensifier. The shoulder should be draped free to allow for this (Fig 19-10).

332

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19

5

Clavicle

Operative procedure

(cont) Towel clips

Pointed reduction forceps or towel clips are used to grasp both of the fragments for reduction to the precontoured plate (Fig 19-11). Manipulators

Two pins, one in each main fracture fragment, are applied perpendicular to the predetermined plate position and used as joysticks to manipulate and reduce the fracture. Once fracture reduction is obtained, the two pins are locked in position with the help of rods and clamps just like an external fi xator.

Fig 19-10 The whole upper extremity should be able to be mobilized freely during the operation.

a

b

c

Fig 19-11a–c The precontoured plate is passed under the skin and the fracture is reduced using pointed reduction forceps. This technique is useful in oblique fractures.

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5 5.3

Operative procedure

(cont)

Plate and screw insertion

The contoured plate is next inserted through the skin incision into a subcutaneous tunnel over the clavicle. Cortex screws are inserted, one on each end of the plate, to fi x the plate to the bone. Fracture reduction and plate position are checked and, if satisfactory, the rest of the screws are inserted as planned to complete the fi xation. When both cortex screws and LHS are used, the former should be inserted fi rst as a reduction screw and to stabilize the plate in proper position. In general, three screws fi xed bicortically are required on each main fracture fragment. 5.4

Step-by-step operative procedure

The upper chest, shoulder, arm, and forearm are cleaned and draped. The whole upper extremity should be able to be moved freely during the operation (see shoulder manipulation; Fig 19-10). The outline of the clavicle, including the fracture, is marked on the skin. The position of the plate, as well as the location of the skin incisions, is similarly marked (Fig 19-12). Through a stab wound, a drill hole is prepared to insert a pin on each side of the fracture. Fracture reduction is performed manually, and controlled by the image intensifier in AP and 45º upward projection. The assistant may simultaneously manipulate the shoulder to help in the fracture reduction (Fig 19-13a–b).

The reduction is maintained with an external fi xator after satisfactory reduction is achieved (Fig 19-13c). Two skin incisions, each 2–3 cm long, are made over the clavicle corresponding in position to the ends of the preselected plate. A subcutaneous tunnel is created (Fig 19-14a). A threaded drill guide for the LCP is screwed into the second last holes of the plate and then used as handle for plate introduction. The precontoured plate is slipped into the subcutaneous, extraperiosteal tunnel and the plate position is adjusted correctly with the help of the image intensifier (Fig 19-14b). The second last holes medially and laterally are drilled and the drills left in place, together with the drill sleeves, for temporary plate fi xation (Fig 19-14c–d). The most medial and most lateral plate holes are prepared for fi xation with cortex screws. These two screws will push the plate as close to the bone as possible to minimize plate prominence under the skin. Cortex screws may also be used to complete the fi xation (medially and laterally) if the bone quality is good (Fig 19-14e). The drill bits used for temporary plate fi xation in the second last holes on both sides of the plate are replaced with LHS or cortex screws. Three screws are fi xed bicortically on each side of the fracture (Fig 19-14f ).

334

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19

5

Clavicle

Operative procedure

a

(cont)

b

c

Fig 19-12a–c

The clavicle is outlined with marker pen and the precontoured plate is placed to locate the incision and insertion point for Schanz screw.

a Fig 19-13a–c

b

c

Indirect reduction by using external fi xator and maintained reduction.

335

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5

Operative procedure

(cont)

a

b

c

d

e

f

Fig 19-14a–f

Surgical steps: plate introduction and fi xation.

336

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19

6

Clavicle

Postoperative care and rehabilitation

Range-of-motion and muscle-strengthening exercises for the shoulder are started early. Load-bearing activities on the clavicle should be delayed until there are radiological signs of fracture healing. 7

Pitfalls –

8

Pearls +

Pitfall 1

Pearl 1

Care should be exercised when using sharp tools such as drill bits, Schanz screws, and K-wires in this region in order to avoid injury to the lung, vessels, and the brachial plexus.

In clavicular shaft fractures, preoperative planning is essential to select the appropriate type and length of the plate which needs to be contoured accurately in order to reduce subcutaneous plate prominence.

Pitfall 2

Pearl 2

Tunneling should be done with care so that the periosteum is not stripped off from the bone.

Standard cortex screws work well for indirect fracture reduction. If used in conjunction with LHS, the former should be inserted fi rst as a reduction screw and to stabilize the plate in proper position.

Pitfall 3

Pearl 3

Rotational malalignment may occur during fracture reduction and should be corrected before defi nitive fracture fi xation takes place.

A regular reconstruction plate 3.5 can also be used in the MIPO technique if an LCP reconstruction plate 3.5 is not available.

337

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9

Suggested reading

Harnroongroj T, Vanadurongwan V (1996) Biomechanical aspects of plating osteosynthesis of transverse clavicular fracture with and without inferior cortical defect. Clin Biomech (Bristol, Avon); 11(5):290–294. Hill JM, McGuire MH, Crosby LA (1997) Closed treatment of displaced middle-third fractures of the clavicle gives poor results. J Bone Joint Surg [Br]; 79(4):537–539. Jupiter JB, Ring D (1999) Fractures of the clavicle. Disorders of the Shoulder: Diagnosis and Management. Jupiter JB, Ring D (eds). Philadelphia: Lippincott Williams & Wilkins; 709–736. Poigenfurst J, Rappold G, Fischer W (1992) Plating of fresh clavicular fractures: results of 122 operations. Injury; 23(4):237–241. Proubasta IR, Itarte JP, Caceres EP, et al (2002) Biomechanical evaluation of fi xation of clavicular fractures. J South Orthop Assoc; 11(3):148–152. Riemer BL, Butterfield SL, Daffner RH, et al (1991) The abduction lordotic view of the clavicle: a new technique for radiographic visualization. J Orthop Trauma; 5(4):392–394. Shen WJ, Liu TJ, Shen YS (1999) Plate fi xation of fresh displaced midshaft clavicle fractures. Injury; 30(7):497–500. Sommer Ch, Bereiter H (2005) [Actual relevance of minimal invasive surgery in fracture treatment]. Ther Umsch; 62(2):145–151. German. Weinberg B, Seife B, Alonso P (1991) The apical oblique view of the clavicle: its usefulness in neonatal and childhood trauma. Skeletal Radiol; 20(3):201–203. Zenni EJ Jr, Krieg JK, Rosen MJ (1981) Open reduction and internal fi xation of clavicular fractures. J Bone Joint Surg [Am]; 63(1):147–151.

338

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Author

19.1 1

Vajara PHIPHOBMONGKOL

Clavicle, shaft: spiral wedge fracture—OTA 15-B1

Case description

A 21-year-old soldier was transferred from another hospital one day after being injured in a road traffic accident. He sustained a fracture of the midshaft of the right clavicle associated with a fracture of the proximal right humerus.

a

b

Fig 19.1-1a–b a b

2

Fracture of middle third of the shaft of the right clavicle (OTA 15-B1). Fracture of the proximal right humerus (Müller AO Classification 11-A3).

Indication for MIPO

Ipsilateral fractures of the clavicle and humeral neck (“floating shoulder”) are indications for surgical stabilization.

3

Patient positioning

The patient lies on a radiolucent operating table and the skin is prepared and draped so that the whole upper extremity can be mobilized freely.

The fracture of the proximal right humerus was treated by a locking proximal humeral plate (LPHP). The fracture of the right clavicle was fi xed with an LCP reconstruction plate 3.5 by MIPO.

339

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19

4

Clavicle

Surgical approach

An LCP reconstruction plate 3.5 is selected and contoured according to preoperative planning.

Fig 19.1-3

Skin markings for location of the plate, plate holes, pinning locations, both proximal and distal incisions for plate insertion, should be drawn (AP view).

Fig 19.1-2 The precontoured plate is used as a template on the clavicle under fluoroscopic guidance to determine the proper location of the plate before skin marking.

5

Reduction and fixation

Fig 19.1-5

Fig 19.1-4

Two pins are applied on the anterior surface of each fragment as manipulators. Closed reduction is performed under image intensifier and the external fi xator frame is fi xed (view from top).

The plate is inserted through the incision either from lateral to medial or medial to lateral. Note that threaded drill sleeves are inserted in the second last holes medially and laterally of the LCP and used as handles to adjust the position of the plate.

340

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19.1

5

Clavicle, shaft: spiral wedge fracture—OTA 15-B1

Reduction and fixation

(cont)

Fig 19.1-6a–b a

The plate is temporarily fi xed monocortically to the clavicle with LCP drills into the second last holes medially and laterally. Fine tuning for fracture reduction will be achieved with cortex screws (view from top). b Temporary fi xation with two drill bits.

a

b

a

b

c

Fig 19.1-7a–f a

The cortex screws have to be inserted into the most medial and lateral plate holes to push the plate to the bone in order to minimize plate prominence.

b c

The third hole laterally is fi lled with another cortex screw to further push the plate to the bone. An LHS is used in the nearest hole to the fracture site medially after adequate reduction is obtained. If more reduction is required a cortex screw may be applied instead.

341

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19

5

Clavicle

Reduction and fixation

(cont)

d

e

Fig 19.1-7a–f d e f

f

(cont)

The second hole laterally should be fi lled with an LHS. An LHS should also be fi xed into the second hole medially. Remove the external fi xator. At least three screws fi xed bicortically on each side of the fracture are recommended.

342

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19.1

6

Clavicle, shaft: spiral wedge fracture—OTA 15-B1

Rehabilitation

Postoperatively the patient used an arm sling for 1 week followed by early muscle strengthening and range-of-motion exercises for the right shoulder. The patient had neither local pain nor any postoperative complication. The range of motion

a

b

of the right shoulder 1 month after surgery was satisfactory except for abduction, which was limited to 90º because of the proximal humeral fracture. Internal and external rotation were as shown in Fig 19.1-8 .

c

Fig 19.1-8a–c a b–c

Abduction of the shoulder is about 90º due to the complex fracture of the humerus. Internal and external rotation 1 month after surgery were satisfactory.

Fig 19.1-9

Incision scars were minimal 1 month postoperatively.

343

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19

6

Clavicle

Rehabilitation

(cont)

a

b

c

d

Fig 19.1-10a–d a–b c–d

X-rays AP and upward 45º projection of the clavicle 1 month postoperatively. X-rays AP and lateral of the proximal humerus 1 month postoperatively.

Fig 19.1-11a–b a b

Abduction of the shoulder 2 months postoperatively. Abduction of the shoulder at 3 months. The patient had good range of motion due to early mobilization and rehabilitation after fi xation of the proximal humerus and clavicle.

a

b

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19.1

6

Clavicle, shaft: spiral wedge fracture—OTA 15-B1

Rehabilitation

(cont)

Fig 19.1-12

X-ray AP of the clavicle 2 months postoperatively, show early union of the fracture.

Fig 19.1-13

Fig 19.1-14 3 months postoperatively, both the clavicle and the proximal humeral fracture show good healing.

Fig 19.1-15

The surgical scars were minimal. The prominence of the plate over the clavicle was unavoidable.

X-rays of the right clavicle after plate removal show good bony healing and alignment.

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19

7

Clavicle

Pitfalls –

8

Pearls +

Pitfall 1

Pearl

Introduction of any sharp edge tools to the clavicle is dangerous. This should be kept in mind throughout the procedure.

Contouring of the plate and the use of cortex screws functioning as reduction screws, are helpful for the fi ne tuning of fracture reduction after temporary fi xation with manipulators.

Pitfall 2

The drill bit should be sharp enough to avoid applying too much force on the drill during drilling. Drill slipping on the bone may cause serious complications.

346

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Author

19.2 1

Vajara PHIPHOBMONGKOL

Clavicle, shaft: simple transverse fracture—OTA 15-A3

Case description

A 21-year old male was injured in a motorcycle accident. He sustained fractures of the midshafts of his left clavicle and left femur. The skin over the left clavicle was tented due to marked displacement of the fracture.

Fig 19.2-1a–b a

a

2

b

Indication for MIPO

The fracture of the left clavicle was markedly displaced with skin tenting. This is an indication for surgical reduction and fi xation. The presence of an associated left femoral shaft fracture is another indi-

Fracture of midshaft left clavicle, (OTA 15-A3) with marked displacement. b Fracture of midshaft of left femur (Müller AO Classification 32-B2).

3

Patient positioning

The patient lies on a radiolucent operation table and the skin is prepared and draped so that the whole upper extremity can be mobilized freely.

cation for fi xation of the left clavicular fracture so that ambulation with crutches and rehabilitation are facilitated. (The left femoral shaft fracture was treated by closed reamed intramedullary nailing.)

4

Surgical approach

An LCP reconstruction plate 3.5 is precontoured for application to the anterior aspect of the clavicle.

Fig 19.2-2 The selected length of the LCP reconstruction plate is contoured with the help of a template.

347

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19

4

Clavicle

Surgical approach

(cont)

a

b

Fig 19.2-3a–b

Fig 19.2-4 Skin incisions of 3 cm on the medial and lateral sides of the clavicle. A small periosteal elevator can be used as a tunneler to create a space between periosteum and the subcutaneous tissue.

a

After skin preparation and draping, the clavicle is marked out on the skin (view from top left). b The planned position of the precontoured plate is also marked.

5

Reduction and fixation

a

b

c

Fig 19.2-5a–c a

The plate is inserted either from lateral to medial or medial to lateral. The position of the plate is appropriately adjusted under fluoroscopic guidance. Pointed reduction clamps are used as reduction tools applied percutaneously via small puncture incisions. Reduction by manipulation of the shoulder is done simultaneously. b A cortex screw is introduced and tightened until the plate is pushed against the bone. If the plate has been contoured accurately, the fracture will be easily reduced. c When adequate reduction is achieved, the locking head screws (LHS) are inserted one by one. The x-ray shows 45º upward projection of the clavicle.

348

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19.2

6

Clavicle, shaft: simple transverse fracture—OTA 15-A3

Rehabilitation

The patient was discharged from the hospital 3 days after the operation with axillary crutches. Range-of-motion exercises for the shoulder were started. After 2 weeks, partial weight bearing on the left femur was allowed with the use of crutches.

Fig 19.2-6

Skin condition 2 weeks postoperatively. The abrasions on the clavicle due to the primary injury healed well and all incision scars were acceptable.

b

c

Fig 19.2-7a–c Range of motion of the shoulder 2 weeks after surgery. The patient was able to fully elevate the shoulder, with satisfactory internal and external rotation.

a

Fig 19.2-8

The patient was able to use crutches for nonweight bearing walking without difficulty. 349

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19

6

Clavicle

Rehabilitation

(cont) Fig 19.2-9a–b a

a

This x-ray shows callus formation 2 months after MIPO. The patient had no pain. b 4 months after MIPO, solid union was achieved and the fracture line was obliterated with good callus. The patient had full function of the shoulder.

b

a Fig 19.2-10 The surgical scars at 8 months postoperatively. Due to the plate prominence, it was removed easily through the original incisions.

b

Fig 19.2-11a–b a b

X-ray 8 months after surgery in AP view. X-ray viewed from top, solid union of the clavicular shaft. It was recommended to remove the plate after bony union due to the prominence of the plate on the skin.

350

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19.2

7

Clavicle, shaft: simple transverse fracture—OTA 15-A3

Pitfalls –

8

Pearls +

Pitfall 1

Pearl 1

Malrotation is possible if the temporary fi xation or reduction is not fully stable.

A pointed reduction clamp is useful for reduction.

Pitfall 2

Pearl 2

If the plate is applied from anterior, screw fi xation at the distal end of the clavicle will be difficult because of the flatness of the bone in this area.

Preoperative plate contouring is mandatory.

Pitfall 3

Anterior plating might result in more prominence of the plate than superior plating since the plate is in vertical position, especially at the flat part of the distal end of the clavicle.

351

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19

Clavicle

352

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Author

19.3 1

Vajara PHIPHOBMONGKOL

Clavicle, shaft: simple oblique fracture—OTA 15-A2 with marked displacement

Case description

A 22-year old male with a closed fracture of left clavicle.

b Fig 19.3-1a–b AP view and upward projection of the left clavicle.

a

2

Indication for MIPO

The fracture of the clavicle was markedly displaced with skin tethering. This is an indication for reduction and fi xation. The MIPO technique was selected because of its biological advantages.

4

3

Patient positioning

The patient lies on a radiolucent operation table and the skin is prepared and draped so that the whole upper extremity can be mobilized freely.

Surgical approach

The patient was operated with the technique described in case 19.2.

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19

5

Clavicle

Reduction and fixation

a

b

Fig 19.3-2a–b

6

Early postoperative x-rays, AP and upward 45º projection.

Fracture reduction was carried out with the help of bone hooks. When adequate reduction was achieved LHS were applied; fi rstly into the most medial and most lateral plate holes, followed by LHS near the fracture on each side. One additional screw was added in the middle of the lateral fracture segment to improve the stability of the fi xation.

Rehabilitation

a

Fig 19.3-3

Surgical scars 1 month after surgery. There is some prominence of the plate, but the patient had no pain.

Fig 19.3-4 1 month postoperatively, the patient has regained full range of motion of the left shoulder.

b Fig 19.3-5a–b

X-rays 1 month postoperatively, AP and upward 45º projection.

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19.3

6

Clavicle, shaft: simple oblique fracture—OTA 15-A2 with marked displacement

Rehabilitation

(cont)

Fig 19.3-6a–b a b

a

7

b

Pitfalls –

8

X-ray 2 months postoperatively. Upward projection 2 months postoperatively shows more callus formation than the early postoperative x-ray, and the fracture line is obliterated.

Pearls +

Pitfall 1

Pearl

Plate prominence will be apparent if contouring is not accurate and if the cortex screws for reduction were not introduced fi rst into the most medial and most lateral holes.

The bone hook is a simple tool for reduction.

Pitfall 2

It is difficult to maintain reduction without temporary fi xation during plate application.

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19

Clavicle

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Author

19.4 1

Vajara PHIPHOBMONGKOL

Clavicle, shaft: simple transverse fracture—OTA 15-A3

Case description

A 25-year old male with closed fracture of left clavicle was referred to hospital 2 weeks after the injury. He also had left brachial plexus injury.

a

2

Fig 19.4-1a–b Fracture of midshaft left clavicle (OTA 15-A3). There was severe displacement of the fracture which correlated with the clinical presentation of brachial plexus injury.

b

Indication for MIPO

3

The fracture of the clavicle was severely displaced and this is an indication for surgery.

4

Patient positioning

The patient lies on a radiolucent operating table and the skin is prepared and draped so that the upper extremity can be mobilized freely.

Surgical approach—reduction and fixation

The same technique as described in case 19.1 was used.

Fig 19.4-2

Early postoperative x-ray, AP view.

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19

5

Clavicle

Rehabilitation

a Fig 19.4-3 Skin incisions, 2 weeks after surgery, following removal of stitches. The patient gained nearly full range of motion of the shoulder without pain.

Fig 19.4-4a–b

a

b

2 months follow-up x-rays in AP and 45º upward projection.

b

c

Fig 19.4-5

Fig 19.4-6a–c 1 year after surgery, the patient has recovered from the brachial plexus injury and has regained full range of motion of the upper extremity.

Fig 19.4-7

Fig 19.4-8 1 year follow-up 45º upward x-ray projection shows that the fracture has healed without any complication. The fracture gap seen on the early postoperative x-ray was bridged and healed well with this technique.

1 year after surgery the surgical wounds healed well without complication.

1 year follow-up AP x-ray shows solid fracture union.

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Glossary With acknowledgments to Christopher L Colton, Christopher G Moran, Stephan M Perren, and Michael Wagner

The glossary provides the working defi nitions for terms that have been used by authors throughout the book. We hope the glossary will help readers understand the text and also be useful for surgeons taking postgraduate examinations. abduction

Movement of a part away from the midline.

adduction

Movement of a part toward the midline.

allograft

Bone or tissue transplanted from one individual to

articular fracture—partial

Only part of the joint is involved while the remainder remains attached to the diaphysis. There are several varieties: multifragmentary depression A fracture in which part of the joint is depressed and the fragments are completely separated. pure depression An articular fracture in which there is depression alone of the articular surface without split. The depression may be central or peripheral. pure split An articular fracture in which there is a longitudinal metaphyseal and articular split, without any additional osteochondral lesion. split depression A combination of a split and a depression, in which the joint fragments are usually separated.

another. anatomical position

The reference position of the body— standing facing the observer, with the palms of the hands facing forward.

anatomical reduction

Reinstatement of the exact prefracture

shape of the bone. angular stability

The property of an implant construct, which is designed so that discrete parts of the implant, when assembled, are fi xed in their angular relationship to each other, to stabilize the fracture. Usually applied to plates and screws, when the screw heads, once driven home in the plate hole, are interconnected with the plate—this is achieved by an external thread on the screw head which engages with an internal thread in the plate hole.

autograft Graft of tissue from one site to another within the same individual (homograft). avascular necrosis (often abbreviated as AVN)

Bone which has been deprived of its blood supply dies. In the absence of sepsis, this is called avascular necrosis. The dead bone retains its normal strength until the natural process of revascularization, by creeping substitution, starts to remove the dead bone, in preparation for the laying down of new bone. Loaded areas may then collapse. avulsion Pulling off, eg, a bone fragment pulled off by a ligament or muscle attachment is an avulsion fracture. biological internal fixation

Prevents shear displacement of a fragment by functioning as a buttress.

A technique of surgical exposure, fracture reduction, and fi xation including the bone–implant interface which favors the preservation of the blood supply and thereby optimizes the healing potential of the bone and soft tissue.

articular fracture—complete

bone graft

antiglide plate

The entire articular surface is separated from the diaphysis.

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to restore skeletal continuity where there has been bone loss— see allograft and autograft .

coronal

This is a vertical plane of the body passing from side to side, so that a coronal bisection of the body would cut it into a front half and a back half. Also called the frontal plane.

bone healing —see healing cortical bone butterfly fragment Where there is a fracture complex with a third fragment which does not comprise a full cross-section of the bone (ie, after reduction there is some contact between the two main fragments), the small wedge-shaped fragment, which may be spiral, is occasionally referred to as a butterfly fragment—see wedge fracture.

The dense bone forming the tubular element of the shaft, or diaphysis (middle part) of a long bone. The term is also applied to the dense, thin shell covering the cancellous bone of the metaphysis.

continuous passive motion (CPM) The use of apparatus to provide periods of passive movement of a joint through a controlled range of motion.

buttress

Construct that resists axial load by applying force at 90° to the axis of potential deformity.

creeping substitution

The slow replacement of dead bone with

living, vascular bone. callus

A complex tissue of immature bone and cartilage that is formed at the site of bony repair.

cancellous bone Spongy trabecular bone, found mostly at the proximal and distal bone ends.

closed reduction—internal fixation (CRIF)

A widely used abbreviation for closed indirect reduction without exposure of fracture zone and internal fi xation (osteosynthesis).

debridement

compartment syndrome Raised pressure in a closed fascial compartment that results in local tissue ischemia—see muscle compartment .

The surgical excision from a wound or pathological area, of foreign material and all avascular, contaminated, and infected tissue. deformity

Any abnormality of the form of a body part.

complex fracture

Fracture with one or more intermediate fragment(s) in which there is no contact between the main fragments after reduction.

delayed union

Union is not taking place at what is accepted as the expected time course for a particular fracture (and the patient’s age).

compression

The act of pressing together to increase or achieve stability.

diaphysis

The cylindrical, or tubular, part between the ends of a long bone, often referred to as the shaft.

compression screw —see lag screw. contact healing

Occurs between two fragments of bone maintained in motionless contact. The fracture is then repaired by direct internal remodeling.

dislocation A displacement of a joint such that no part of one articular surface remains in contact with the other. Sometimes used incorrectly to denote fracture displacement.

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Glossary

displacement

The condition of being or moving out of place. A fracture is displaced if the fragments are not perfectly anatomically aligned. The fragments of a fracture displace in relation to each other. The displacement may be reversible or irreversible. distal

external fixation

Skeletal stabilization using pins, wires, or screws that protrude through the skin and are linked externally by tubes or other devices. extraarticular fracture

Does not involve the articular surface but may be within the capsule of the joint.

Away from the center of the body, more peripheral. far cortex

The cortex more distant from the operator.

distractor

An instrument applied to effect distraction of a joint or fracture in order to facilitate fracture reduction. It can also be used to maintain the reduction once it has been achieved to facilitate fracture fi xation.

fasciotomy The surgical division of the wall of a muscle compartment, usually to release high intracompartment pressure—see compartment syndrome, and muscle compartment .

dorsal Pertaining to the back—or dorsum—of the body in the anatomical position. An exception is the foot; the top of the foot, even though it faces forward in the anatomical position, is called the dorsum.

fibrocartilage Tissue consisting of elements of cartilage and of fibrous tissue. It is the normal constituent of the menisci and the triangular fibrocartilage at the wrist. It forms as the repair tissue after injury to articular cartilage.

ductility The ability of a material to develop significant, permanent deformation before it breaks—see plastic deformation.

fracture disease A condition characterized by disproportionate pain, soft-tissue swelling, patchy bone loss, and joint stiffness. Linked terms are reflex sympathetic dystrophy (RSD), and Sudeck’s atrophy.

dynamization Increasing mechanical load across a fracture to enhance bone formation. elastic deformation —see plastic deformation. endosteum

A single layered membrane that lines the interior surface of the bone, ie, the wall of the medullary cavity. Its cells have osteogenic potential.

fracture fixation Application of a mechanical device to a broken bone to allow healing in a controlled position and (usually) early functional rehabilitation. The surgeon determines the degree of reduction required and the mechanical environment that influences the mode of healing. gliding hole

energy transfer

When tissue is injured, the damage is due to energy that is transferred to the tissue. This is most commonly due to the transfer of kinetic energy from a moving object (car, missile, falling object, etc).

epiphysis

The end of a long bone which lies upon the growth plate in a child’s skeleton—see metaphysis .

The cortex under the screw head is drilled to the size of thread diameter so that the thread gets no purchase. It is used for lag screw techniques.

gliding splint A splint (such as an unlocked intramedullary nail) which allows some displacement of the fracture fragment, eg, axial shortening.

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goal of fracture treatment

According to Müller et al, the goal of fracture treatment is to restore optimal function of the limb in respect to mobility and load-bearing capacity while avoiding complications.

healing—indirect

Haversian system The cortical bone is composed of a system of small channels (osteons) about 0.1 mm in diameter. These channels contain the blood vessels and are remodeled after a disturbance of the blood supply to bone. There is a natural turnover of the Haversian systems by continuous osteonal remodeling; this process is part of the dynamic and metabolic nature of bone. It is also involved in the adaptation of bone to an altered mechanical environment. Direct fracture healing may be a side effect of osteonal remodeling of necrotic bone.

impacted fracture A fracture in which the opposing bony surfaces are driven one into the other.

healing

Recovery of original integrity; clinical bone healing; regarded as complete when bone has regained adequate stiffness and strength to withstand functional loading.

healing—direct

Observed following internal fi xation with absolute stability. It is characterized by the absence of callus; there is no resorption at the fracture site. Bone forms by internal remodeling without intermediate repair tissue. Direct fracture healing was formerly called “primary” healing. Direct healing takes 1–2 years until safe functional loading after implant removal is possible.

healing—contact Direct bone healing due to internal remodeling when there is absolute stability and the bone ends are in contact. healing—gap

Direct bone healing when there is absolute stability but a small gap between the fracture fragments. Lamellar bone forms in the gap and is then remodeled by penetrating osteons.

Bone healing by callus formation in fractures treated either with relative stability, or left untreated. Indirect healing takes only a few months to regain adequate stiffness and strength for functional loading—see callus .

interfragmentary compression

Bone fragments are pressed together, either with a lag screw or plate, to produce preloading and friction between the fragments according to the principle of absolute stability.

internal fixator A fi xator placed inside the body. The internal fi xator replaces the clamps by locking threaded pins (screws) within the plate hole. The fully implanted internal fi xator resembles a plate but functions like a fi xator, ie, its stiffness reduces load dependent deformation or displacement. Like the external fi xator, when elevated from the bone surface, it does not require exact shaping to fit the bone surface. It can, therefore, be used without broad surgical exposure (MIPO). ischemia

Reduction in blood flow resulting in tissue

hypoxia. joystick A Schanz screw or threaded pin with an attached handle inserted into a fracture fragment to allow direct manipulation of the fragment to effect fracture reduction. lag screw A screw that passes through a gliding hole to grip the opposite fragment in a threaded hole, producing interfragmentary compression when it is tightened. locking plate A plate with screw holes that allow mechanical coupling to a locking head screw. The less invasive stabiliza-

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Glossary

tion system (LISS) will accept only this type of screw, while locking compression plates (LCP) have a combination hole that will accept standard (nonlocking) screw heads or threaded (locking) screw heads.

multifragmentary fracture

A fracture with more than one fracture line so that there are three pieces or more—see also complex fracture. muscle compartment

locking head screw (LHS) Screws with threads cut into the head which provide a mechanical coupling to a threaded screw hole in a plate, thereby creating an angular and axial stable device, ie, after application the screw cannot tilt or move along its long axis. malunion

The fracture has healed in a position of deformity.

manipulators

Threaded pins with attached handles inserted into the main fragments on either side of the fracture to allow manipulation and indirect reduction under fluoroscopic guidance. Following fracture reduction, the manipulators can be connected with clamps and a rod to maintain the reduction to facilitate fracture fi xation.

An anatomical space, bounded on all sides either by bone or deep fascia which contains one or more muscle bellies. near cortex

The cortex near the operator and on the side of insertion of an implant. neutralization plate A plate, or other implant, which reduces the load placed on a lag screw fi xation, thus protecting it from overload. This term has been replaced by protection plate. nonunion

The fracture is still present and healing has stopped. Under no circumstances will the fracture unite without surgical intervention. It is usually due to improper mechanical or biological conditions—see union, pseudarthrosis , and delayed union.

metaphysis

In the adult, this is the segment of a long bone located between the articular surface and the shaft (diaphysis). It consists mostly of cancellous bone within a thin cortical shell.

ORIF A widely used abbreviation for open reduction and internal fi xation (osteosynthesis). osteoarthritis

minimally invasive plate osteosynthesis (MIPO) Reduction and plate fi xation without direct surgical exposure of the fracture site, using small skin incisions and subcutaneous, or submuscular, insertion of the plate. minimally invasive surgery Any surgical procedure undertaken using small skin incisions. Examples include laparoscopic abdominal surgery, arthroscopy, and closed intramedullary nailing.

A condition of synovial joints which is characterized by loss of articular cartilage, subchondral bone sclerosis, bone cysts, and the formation of osteophytes.

osteomyelitis

An acute or chronic inflammatory condition affecting bone and its medullary cavity, usually the result of infection.

osteon

The name given to the small channels which combine to make up the Haversian system in cortical bone.

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osteopenia

A reduction in bone mass between 1 and 2.5 standard deviations below the mean for a young adult (ie, a T score of –1 to –2.5)—see osteoporosis .

polytrauma

Multiple injury to one or more body systems or cavities with sequential systemic reactions. An Injury Severity Score (ISS) of more than 15 is usually taken to indicate polytrauma.

osteoporosis

A reduction in bone mass more than 2.5 standard deviations below the mean for a young adult (ie, a T score of < –2.5)—see osteopenia, and pathological fracture.

osteosynthesis

A term coined by Albin Lambotte to describe the “synthesis” (derived from the Greek for putting together, or union) of a fractured bone by a surgical intervention using implanted material. It differs from “internal fi xation” in that it also includes external fi xation. osteotomy

prebending (of plate) An exactly contoured plate is given a slight extra bend at the level of a transverse fracture, so that its central portion stands slightly off the underlying cortex. As compression is applied, the far cortex is compressed fi rst, then the near cortex (without the bend, the plate may only compress the near cortex—this is not a stable situation). precontour (of plate)

Preoperative or intraoperative bending of a plate to match the external surface of the bone exactly.

Controlled surgical division of a bone. precise reduction —see anatomical reduction.

overbending (of plate) —see prebending (of plate). preload pathological fracture

A fracture through abnormal bone which occurs at normal physiological load or stress.

periosteum The fibrovascular membrane covering the exterior surface of a bone. The deep cell layer has osteogenic potential.

The application of interfragmentary compression keeps the fragments together until a tensile force is applied which exceeds the compression (preload).

protection plate A plate, or other implant, which shares load with bone and thus reduces the load placed on a lag screw fi xation, thus protecting it from destructive overload. This term has replaced neutralization plate.

pilot hole

A drill hole of the same diameter as the core of the screw. This can then be used to guide the insertion of screws that cut their own thread (self-tapping) or a tap that will cut the threads and produce a thread hole.

pin loosening

Bone resorption at an external fi xator pin–bone interface usually the result of interface micromotion.

pseudarthrosis literally means “false joint”. When a nonunion is mobile and allowed to persist for a long period, the bone ends become sclerotic and the intervening soft tissue differentiates to form a type of synovial articulation—see delayed union, nonunion, union. reduction

The realignment of a displaced fracture.

plastic deformation

A permanent change in a material’s length or angle, ie, it will not be reversed when the deforming force is released.

reduction—direct Direct manipulation of fracture fragments with hands or instruments following surgical exposure of the fracture site.

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Glossary

reduction—indirect

Fragments are manipulated indirectly by applying corrective force at a distance from the fracture, by distraction or other means, without opening the fracture site.

reduction screw A screw that pulls a bone, or bone fragment, toward the screw head or plate.

sequestrum

A piece of dead bone lying alongside, but separated from the bony bed from which it came. Infected sequestra are formed in chronic osteomyelitis. Intensification of necrosis-induced porosity may lead to confluence of the pores whereby the dead bone becomes separated and a sequestrum is formed—see osteotomyelitis . shear

reflex sympathetic dystrophy (RSD)

One of the names given to algodystrophy—see fracture disease. refracture A further fracture occurring after a fracture has been solidly bridged by bone, at a load level otherwise tolerated by normal bone. The resulting fracture line may coincide with the original fracture line, or be within the area of bone that has undergone changes as a result of the fracture and its treatment.

A shearing force is one which tends to cause one segment of a body to slide upon another, as opposed to tensile forces, which tend to elongate a body. simple fracture

There is a single fracture line producing two fracture fragments.

splint—locked There are fi xed connections between the bone and splinting device, above and below the fracture zone, so that the working length between the main fragments cannot change (eg, static, locked nail).

relative stability —see stability, relative. splint—gliding remodeling (of bone)

The process of transformation of external bone shape (external remodeling), or of internal bone structure (internal remodeling, or remodeling of the Haversian system).

The connection between the bone and the splinting device allows (controlled) axial movement, so that the distance between the main fragments can change (eg, dynamic, locked nail).

splinting method rigidity

The ability to resist deformation under an applied

load. sagittal

This is a vertical plane of the body passing from front to back, so that a sagittal bisection of the body would cut it into a right half and a left half.

segmental

If the shaft of a bone is broken at two levels, leaving a separate shaft segment between the two fracture sites, it is called a “segmental” fracture complex.

Splinting is a method of fracture fi xation. Movement at the fracture site is reduced by attaching a rigid support to the main bone fragments. The splint may be external (plaster, external fi xators) or internal (plate, intramedullary nail).

split depression

An articular injury with a fracture line running into the metaphysis (split) and impaction of separate osteochondral joint fragments (depression)—see pure split and pure depression.

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stability, absolute

A fi xation construct that allows small amounts of motion in proportion to the load applied. This results in indirect healing by callus formation.

strain). If this exceeds the strain tolerance of the tissue, healing will not take place. If a larger fracture gap is subject to the same movement, the relative change in length will be smaller ie, less strain) and, if the critical strain level is not exceeded, there will be normal tissue function and indirect healing by callus. If the distance between the fractured surfaces is excessive, healing will not occur.

stability of fixation

strain tolerance

Fixation of fracture fragments so that there is virtually no displacement of the fracture surfaces under physiological load. This allows direct bone healing. stability, relative

This is characterized by the degree of residual motion at the fracture site after fi xation.

stiffness The resistance of a structure to deformation. The stiffness of a structure is expressed as its Young’s modulus of elasticity, which is the ratio of stress to strain.

This determines the tolerance of tissue to deformation. No tissue can function properly when an increase in length (ie, strain) causes the tissue to disrupt. This is the critical strain level.

stiffness, bending

strength The ability to withstand load without structural failure. The strength of a material can be expressed as ultimate tensile strength, bending strength, or torsional strength.

stiffness, torsional

stress protection Using an implant to reduce peak loads applied to a screw fi xation—see protection plate.

bending stiffness of an implant is inversely proportional to the square of the working length.

Torsional stiffness of an implant is inversely proportional to the working length.

stress riser

stiffness and geometrical properties

The thickness of a structure affects deformability by its third power. Changes in geometry are, therefore, much more critical than changes in material properties.

A small surface defect (notch) that brings about a concentration of stress. stress shielding Bone deprived of functional stimulation by having its functional load reduced may react in the long term by becoming less dense or strong.

strain

Change in length of a material when a given force is applied. Normal strain is the ratio of deformation (lengthening or shortening) to original length. It has no dimensions but is often expressed as a percentage.

strain induction

Tissue deformation—among other things— may result in induction of callus. This is an example of a mechanically induced biological reaction. strain theory—Perren

With a small fracture gap, any movement will result in a relatively large change in length (ie, high

subluxation A displacement of a joint but with partial contact between the two articular surfaces. Sudeck’s atrophy One of the names given to algodystrophy— see fracture disease. tension band The principle by which an implant , attached to the tension side of a fracture, converts the tensile force into a compressive force at the cortex opposite the implant. While wires, cables, and sutures are often used for tension band

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Glossary

fi xation, plates and external fi xators, when appropriately placed, can also function as tension bands. thread hole

Discussed in conjunction with pilot hole.

toggling

Slight movement at the couple between a screw and a plate or nail. Implants may be designed to allow toggle, eg, intramedullary nails where the tolerance of the assembly does not permit exact fit. Toggle between plates and screws may occur during plate failure with loosening of the implant.

torque The moment produced by a turning or twisting force. As an example torque is applied to drive home and tighten a screw. The moment is equal to the product of lever arm (in meters) and force (in Newtons) producing torsion and rotation about an axis (the unit of torque is Nm).

insertion of a bone graft, and (c) increases the stability because of the distance of the “waved” portion of the implant from the neutral axis of the shaft. Such plating is useful in nonunion treatment. wedge fracture

Fracture complex with a third fragment in which, after reduction, there is some direct contact between the two main fragments—see butterfly fragment .

working length The distance between the two points of implant fi xation (one on either side of the fracture) between an implant, usually an intramedullary nail, and the bone. zone of injury

The entire volume of bone and soft tissue damaged by energy transfer during trauma.

translation

Displacement of one bone fragment in relation to another, usually at right angles to the long axis of the bone— see displacement .

union

The bone has healed and regained its normal stiffness and strength. In clinical terms, this means there is no movement or tenderness at the fracture site and no pain on stressing the fracture site. Radiologically, there should be evidence of bone trabeculae bridging the fracture site.

valgus

Deviation away from the midline in the anatomical position.

varus Deviation toward the midline in the anatomical position. wave plate

The central section of a plate is contoured to stand off the near cortex over a distance of several holes. This leaves a gap between the plate and the bone, which (a) preserves the biology of the underlying bone, (b) provides a space for the 367

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