The Anterior Cruciate Ligament: Reconstruction and Basic Science1

About this Book Why this Book Is Needed The anterior cruciate ligament (ACL) is one of the most written about topics in Orthopaedics, such that it has become very difficult for most Orthopaedists to stay current through regular casual reading of the literature. Yet until now there has not been a comprehensive ACL text. This book fills that gap. We have attempted to present the essence of the world’s accumulated clinically relevant ACL-related knowledge in 81 concise chapters.

in this text, along with the many videos, provide a more in-depth alternative. Through partnership with the leading sports medicine companies, new devices will be introduced on the website along with expert orthopaedic evaluations—“peer reviewed marketing.”

The Technique of ACL Reconstruction The best techniques for each component of ACL reconstruction: harvest, fixation, tunnels, notchplasty, and so forth, are collected and presented. This information leads directly to good outcomes.

About the Associate Editors and Contributors

Choices

The associate editors listed on the cover and the other contributors are a “dream team” of leading ACL surgeons and scientists from around the world who were chosen based on their accomplishments and research on the specific topic of their chapter. Other distinguished surgeons are being continually added as special contributors of new “hot topics” for the ACL website.

After technique, ACL surgery is all about choices: interference versus cortical fixation, bone–patella tendon–bone versus hamstring, auto versus allograft, accelerated versus protected rehab, anterior versus posterior hamstring harvest, metal versus bio versus osteoconductive, single versus double bundle, and so on. Information on both sides of each argument is presented to allow the surgeon to make each choice a well-informed one.

Fixation Devices and Troubleshooting Each of the leading ACL reconstruction fixation devices has its own chapter written by its creator or one of its most skilled users. Each such chapter presents scientific rationale, technique, results, and, most importantly, a troubleshooting section. Every surgeon encounters technical problems during cases, but we know of no other source for the practicing surgeon to find the best way to get out of them. Most device information comes to surgeons from company representatives who do provide a useful service; but the chapters

Related Topics The expert treatment of related pathology— cartilage and ligamentous—is essential for the ACL surgeon, and is presented here. There are also 10 chapters on different types of complications, much of it probably unfamiliar to many. There is original research on the incidence of ACL tears, economics, and stability results. New horizons, including four double bundle techniques, navigation, and tissue engineering are also presented, along with biomechanical information and much more. vii

About this Book

The DVD Dozens of surgical technique videos of the component techniques that make up ACL reconstruction, and a few additional topics, comprise the included DVD. Some videos were created especially for this DVD, others represent classics from the AAOS and elsewhere. All are the best we know of on the given topic and form the only such large collection of ACL videos.

The Website The dedicated website includes an e edition of the book. At this writing there are 10 additional chapters not included in the print version on new “hot topics,” such as quadriceps tendon ACL reconstruction results, and more will be added as new advances or controversies emerge. There are also product introductions in partnership with industry, useful links, course offerings, and much more. The website also includes the “Ask the Experts” and “ACL Database” features described below.

Ask the Experts The contributors to this book have all agreed to field questions from Orthopaedic Surgeons with website passwords on their particular topics, or others. These

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e-mailed queries are directed to a central question center, distributed to the appropriate surgeon, and then answered confidentially to the surgeon who posed the question. The idea is to assist surgeons everywhere to better treat their patients by getting help from the best when they need it.

Staying Current: The ACL Database The book’s short gestation period has ensured that each chapter is up-to-date at publication. However, through the book’s website, significant new ACL-related knowledge is being added each quarter to keep it that way. This is how it works: Beginning in January 2007, every month the 50 or so new ACL-related article references published in the world’s peer reviewed literature have been appended to the bibliography for the most relevant chapter(s) or sections of the text to which they relate. Presentations and even posters from the major sports medicine meetings are similarly categorized each month. Thus, the ACL database presents a continually updated compendium of essentially all the world’s new ACL-related knowledge as it is being created, organized by topic. This is an ideal research tool for any ACL-related topic about which you need to know.

Acknowledgments The special contributors listed on the cover of the book have been involved in this project from the beginning and have supported its development with their time and energy simply because they believed in the worthwhile nature of the project. There are none brighter or more dedicated. I am grateful to them and to all the other esteemed contributing authors: the “dream team” of ACL scientists and surgeons described on the preceding page. I was confident that they would produce the outstanding works of scholarship that they have, but I was continually surprised at how easy to work with these illustrious scientists and surgeons all were and how they respected the time deadlines and constraints of space and organizational structure of the project. This clearly comes

from being passionate about their ideas and their work and is reflected in the high quality of the chapters. I would also like to especially thank one of those contributors, Bert Zarins, for all he taught me about both sports medicine and life as my fellowship mentor many years ago. Kim Murphy and all of the people at Elsevier have been a great pleasure to deal with. She showed enthusiasm and creativity for the project from the beginning and continues to do so. They have also worked diligently to help avoid delays so that the book will be up to date at its publication. Finally, the staff at our clinic and my family have all been wonderful about the time diverted from them to this book.

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List of Contributors Keiichi Akita, MD, PhD Unit of Clinical Anatomy, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan Arturo Almazan, MD Orthopedic Sports Medicine and Arthroscopy Department, National Institute of Rehabilitation; Associate Professor, Sports Medicine Residency Program, National Autonomous University of Mexico, Mexico City, Mexico Andrew A. Amis, PhD, DSc(Eng), FIMechE Professor, Departments of Mechanical Engineering and Musculoskeletal Surgery, Imperial College London, London, England Allen F. Anderson, MD Director, Lipscomb Clinic Research and Education Foundation, Tennessee Orthopedic Alliance, Nashville, Tennessee Christian N. Anderson, MD Resident, Department of Orthopaedic Surgery, Vanderbilt University Medical Center, Nashville, Tennessee John C. Anderson, MD Pacific Orthopaedics and Sports Medicine; Medical Staff, Portland Adventist Medical Center Portland, Oregon

F. Alan Barber, MD, FACS Fellowship Director, Plano Orthopedic and Sports Medicine Center, Plano, Texas Gene R. Barrett, MD Codirector of Knee Service, Mississippi Sports Medicine and Orthopaedic Center, Jackson, Mississippi Guy Bellier, MD Cabinet Goethe, Institut de l'Appareil Locomoteur Nollet, Paris, France Manfred Bernard, MD Priv.-Doz., Klinik Sanssouci, Berlin, Germany Bruce D. Beynnon, PhD Associate Professor, McClure Musculoskeletal Research Center, Department of Orthopaedics and Rehabilitation, College of Medicine, University of Vermont, Burlington, Vermont Robert H. Brophy, MD Fellow, Shoulder/Sports Medicine, Hospital for Special Surgery, New York, New York Charles H. Brown, Jr., MD Medical Director, Abu Dhabi Knee and Sports Injury Centre, Abu Dhabi, United Arab Emirates xi

List of Contributors Taylor D. Brown, MD Bone and Joint Center of Houston, Houston, Texas Anthony Buoncristiani, MD Fellow, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania David Caborn, MD Department of Orthopaedic Surgery, University of Louisville, Louisville, Kentucky Guglielmo Cerullo, MD Clinica Valle Giulia, Roma, Italy Neal C. Chen, MD Clinical Fellow, Sports Medicine and Shoulder Service, Hospital for Special Surgery, New York, New York Pascal Christel, MD, PhD Professor of Orthopaedic Surgery, Institut de l'Appareil Locomoteur Nollet, Paris, France Vassilis Chouliaras, MD Orthopaedic Sports Medicine Center, Department of Orthopaedic Surgery, University of Ioannina, Ioannina, Greece Massimo Cipolla, MD Clinica Valle Giulia, Roma, Italy Philippe Colombet, MD Clinique du Sport de Bordeaux, Mérignac, France Nader Darwich, MD Deputy Medical Director, Abu Dhabi Knee and Sports Injury Centre, Abu Dhabi, United Arab Emirates Laura Deriu, MD Department of Orthopaedics, Catholic University, Rome, Italy Patrick Djian, MD Cabinet Goethe, Institut de l'Appareil Locomoteur Nollet, Paris, France Apostolos P. Dimitroulias, MD Orthopaedic Surgeon, University Hospital of Larissa, Larissa, Greece xii

Lars Ejerhed, MD, PhD Department of Orthopaedics, Northern Älvsborg County Hospital, Uddevalla Hospital, Trollhättan Uddevalla, Sweden Carlo Fabbriciani, MD Professor and Chairman of Orthopaedics and Traumatology, Department of Orthopaedics, Catholic University, Rome, Italy Julian A. Feller, FRACS Associate Professor, Musculoskeletal Research Centre, La Trobe University; Orthopaedic Surgeon, La Trobe University Medical Centre, Melbourne, Victoria, Australia Mario Ferretti, MD Research Fellow, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania Jean Pierre Franceschi, MD Hôpital de la Conception, Marseille, France Ramces Francisco, MD Orthopaedic Surgeon/Affiliate, Orthopaedic Arthroscopic Surgery International, Clinica Zucchi, Milan, Italy Vittorio Franco, MD Clinica Valle Giulia, Roma, Italy Stuart E. Fromm, MD Black Hills Orthopaedic and Spine Center, Rapid City, South Dakota Freddie H. Fu, MD, DSc (Hon), DPs (Hon) David Silver Professor and Chairman, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania John P. Fulkerson, MD Orthopedic Associates of Hartford, P.C.; Clinical Professor and Sports Medicine Fellowship Director, Department of Orthopedic Surgery, University of Connecticut, Farmington, Connecticut William E. Garrett, Jr., MD, PhD Duke Sports Medicine Center, Durham, North Carolina

List of Contributors Anastasios Georgoulis, MD Professor of Orthopaedic Surgery; Chief, Orthopaedic Sports Medicine Center, Department of Orthopaedic Surgery, University of Ioannina, Ioannina, Greece George Giakas, BSc, PhD Department of Sports Science, University of Thessaly, Karyes, Trikala, Greece Enrico Giannì, MD Clinica Valle Giulia, Roma, Italy Thomas J. Gill, MD Assistant Professor, Department of Orthopedic Surgery, Harvard Medical School, Boston, Massachusetts Alberto Gobbi, MD Director, Orthopaedic Arthroscopic Surgery International, Clinica Zucchi, Milan, Italy Steven Gorin, DO Institute of Sports Medicine and Orthopaedics, P.A. Aventura, Florida Tinker Gray, MA, ELS Research Director, Shelbourne Knee Center at Methodist Hospital, Indianapolis, Indiana Letha Y. Griffin, MD, PhD Peachtree Orthopaedic Clinic, Atlanta, Georgia

Stephen M. Howell, MD Professor, Department of Mechanical Engineering; Member of Biomedical Graduate Group, University of California at Davis, Sacramento, California Mark R. Hutchinson, MD Professor of Orthopaedics and Sports Medicine, University of Illinois at Chicago, Chicago, Illinois R.P.A. Janssen, MD Orthopaedic Surgeon, Department of Orthopaedic Surgery and Traumatology, Máxima Medical Center, Veldhoven, Netherlands Timo Järvelä, MD, PhD Department of Orthopaedics and Traumatology, Tampere City Hospital; Tampere University, Tampere, Finland; Department of Orthopaedics Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania Markku Järvinen, MD, PhD Tampere University; Department of Trauma, Musculoskeletal Surgery, and Rehabilitation, Tampere University Hospital, Tampere, Finland Don Johnson, MD, FRCS Director, Sports Medicine Clinic, Carleton University, Ottawa, Ontario, Canada

David R. Guelich, MD Chicago Orthopaedics and Sports Medicine, Chicago, Illinois

Brian T. Joyce, BA Research Coordinator, Illinois Sports Medicine and Orthopaedic Centers, Glenview, Illinois

Yung Han, MD Resident, McGill University Orthopaedic Surgery Residency Program, Montreal, Canada

Auvo Kaikkonen, MD, PhD Inion Oy; Tampere University, Tampere, Finland

Michael E. Hantes, MD Consultant Orthopaedic Surgeon, University Hospital of Larisa, Larisa, Greece

Anastassios Karistinos, MD Assistant Professor, Department of Orthopaedic Surgery, Baylor College of Medicine, Houston, Texas

Aaron Hecker, MA Bioskills Laboratory Manager, Smith and Nephew, Mansfield, Massachusetts

Jüri Kartus, MD, PhD Department of Orthopaedics, Norra Älvsborg/Uddevalla Hospital, Trollhättan, Sweden xiii

List of Contributors John F. Keating, BA, MB, BCh, BAO, MPhil, FRCSI, FRCSEd Consultant Orthopaedic Surgeon, Department of Trauma and Orthopaedics, Royal Infirmary of Edinburgh, Edinburgh, United Kingdom James Kercher, MD Emory School of Medicine, Emory University, Atlanta, Georgia Petteri Kousa, MD, PhD Department of Orthopaedics; Department of Surgery, University of Tampere, Tampere University Hospital, Tampere, Finland; Department of Orthopaedics and Rehabilitation, McClure Musculoskeletal Research Center; Department of Orthopaedics and Rehabilitation, College of Medicine, University of Vermont, Burlington, Vermont Jason Koh, MD Northwestern Medical Faculty Foundation, Chicago, Illinois Michael Kuhn, MD Clinical Instructor, Surgery, Uniformed Services University, Bethesda, Maryland; Fellow, Department of Orthopaedic Surgery and Sports Medicine, New England Baptist Hospital, Boston, Massachusetts Bert R. Mandelbaum, MD Santa Monica and Orthopaedic and Sports Medicine Foundation, Santa Monica, California Robert G. Marx, MD, MSc, FRCSC Associate Professor of Orthopedic Surgery and Public Health, Weill Medical College of Cornell University; Attending Orthopedic Surgeon; Director, Foster Center for Clinical Outcome Research, Hospital for Special Surgery, New York, New York Brian P. McKeon, MD Assistant Clinical Professor of Orthopedics, Tufts University; Head Team Physician, Boston Celtics, Boston Sports and Shoulder Center, Chestnut Hill, Massachusetts xiv

Giuseppe Milano, MD Associate Professor, Department of Orthopedics, Catholic University, Rome, Italy Mark D. Miller, MD Professor, Department of Orthopaedic Surgery, Director of Sports Medicine, University of Virginia; Team Physician, James Madison University, Charlottesville, Virginia Kai Mithoefer, MD Clinical Instructor in Orthopedic Surgery, Harvard Medical School; Harvard Vanguard Orthopedics and Sports Medicine, Brigham and Women's Hospital, Boston, Massachusetts Tomoyuki Mochizuki, MD, PhD Section of Orthopedic Surgery, Division of Cartilege Regeneration, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan Anna-Stina Moisala, MD Tampere University, Tampere, Finland Craig D. Morgan, MD The Morgan-Kalman Clinic, Wilmington, Delaware Constantina Moraiti, MD Department of Orthopaedic Surgery, Orthopaedic Sports Medicine Center of Ioannina, University of Ioannina, Ioannina, Greece Takeshi Muneta, MD, PhD Section of Orthopedic Surgery, Division of Cartilege Regeneration, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan Brian J. Murphy, MD Freeworld Imaging, Miami, Florida Janne T. Nurmi, DVM, PhD Inion Oy; Faculty of Veterinary Medicine, Department of Clinical Veterinary Sciences, University of Helsinki, Tampere, Finland

List of Contributors Nicholas E. Ohly, MBBS, MRCSEd Specialist Registrar, Department of Trauma and Orthopaedics, Royal Infirmary of Edinburgh, Edinburgh, United Kingdom Antti Paakkala, MD, PhD Department of Radiology, Tampere University Hospital, Tampere, Finland Lonnie E. Paulos, MD Professor, Orthopedic Surgery, Baylor College of Medicine; Codirector, The Roger Clemens Institute for Sports Medicine and Human Performance, Houston, Texas Hans H. Paessler, MD ATOS Clinic, Center of Knee Surgery, Foot Surgery and Sports Trauma, Heidelberg, Germany Hemant G. Pandit, FRCS (Orth) North Hampshire Hospital, Nuffield Orthopaedic Centre, Oxford, United Kingdom Michael J. Patzakis, MD Professor and Chairman, Department of Orthopaedic Surgery, Keck School of Medicine, University of Southern California; LACþUSC Medical Center, Los Angeles, California Chadwick C. Prodromos, MD President, Illinois Sports Medicine and Orthopaedic Centers; Assistant Professor, Orthopaedic Surgery, Section of Sports Medicine, Rush University Medical Center, Chicago, Illinois Giancarlo Puddu, MD Clinica Valle Giulia, Roma, Italy

New England Baptist Hospital, Boston, Massachusetts Andrew Riff, BS Medical Student, Georgetown University School of Medicine, Washington, DC Stavros Ristanis, MD, PhD Orthopaedic Sports Medicine Center, Department of Orthopaedic Surgery, University of Ioannina, Ioannina, Greece James Robinson, MD Imperial College of Science, Technology and Medicine, London, United Kingdom Julie Rogowski, BS Professional Education Coordinator, Illinois Sports Medicine and Orthopaedic Centers, Glenview, Illinois Abdou Sbihi, MD Hôpital de la Conception, Marseille, France Sven Ulrich Scheffler, MD Sports Medicine and Arthroscopy Service, Department of Orthopaedics and Traumatology, Center for Musculoskeletal Surgery, Charité, Campus Mitte, University Medicine Berlin, Berlin, Germany K. Donald Shelbourne, MD Shelbourne Knee Center at Methodist Hospital; Associate Professor, Department of Orthopaedics, Indiana University School of Medicine, Indianapolis, Indiana Kelvin Shi, MS Statistician, Forest Labs, Inc., New York, New York Konsei Shino, MD, PhD Faculty of Comprehensive Rehabilitation, Osaka Prefecture University, Osaka, Japan

Paul Re, MD Director, Sports Medicine Emerson Hospital Orthopaedic Affiliates, Concord, Massachusetts

Holly J. Silvers, MPT Director of Research, Santa Monica Orthopaedic and Sports Medicine Research Foundation, Santa Monica, California

John Richmond, MD Chairman, Department of Orthopaedics,

Joseph H. Sklar, MD Assistant Clinical Professor, Tufts University School of Medicine; xv

List of Contributors New England Orthopaedic Surgeons, Springfield, Massachusetts

Center for Musculoskeletal Surgery, Berlin, Germany

James R. Slauterbeck, MD Associate Professor, McClure Musculoskeletal Research Center, Department of Orthopaedics and Rehabilitation, College of Medicine, University of Vermont, Burlington, Vermont

Tony Wanich, MD Orthopaedic Resident, Department of Orthopaedic Surgery, Hospital for Special Surgery, New York, New York

James S. Starman, MD Research Fellow, Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania Nicholas Stergiou, PhD HPER Biomechanics Laboratory, University of Nebraska at Omaha, Omaha, Nebraska Neil P. Thomas, BSC, MB, BS, FRCS North Hampshire Hospital, Basingstoke, United Kingdom; Hampshire Clinic, Wessex Knee Unit, Hampshire, United Kingdom Fotios Paul Tjoumakaris, MD Attending Physician, Department of Orthopaedics, Cape Regional Medical Center, Cape May Court House, New Jersey Harukazu Tohyama, MD, PhD Associate Professor, Department of Sports Medicine, Hokkaido University School of Medicine, Sapporo, Japan Elias Tsepis, BSc, PT, MSc, PhD Associate Professor, Physical Therapy, Supreme Technological Institution of Patra at Aigio, Patra, Greece Frank Norman Unterhauser, MD Center for Musculoskeletal Surgery, Clinic for Trauma and Reconstructive Surgery, Charité, Campus Mitte, Berlin, Germany George Vagenas, BSc, PhD National and Kapodistrian University of Athens, Faculty of Physical Education and Sport Science, Illioupolis, Attiki, Greece Michael Wagner, MD Sports Traumatology and Arthroscopy Service, xvi

Russell F. Warren, MD Professor of Orthopaedics, Weill Medical College of Cornell University; Surgeon-in-Chief, Hospital for Special Surgery, New York, New York Kate E. Webster, PhD Research Fellow, Musculoskeletal Research Centre, La Trobe University, Melbourne, Victoria, Australia Andreas Weiler, MD, PhD Head of Sports Traumatology and Arthroscopy Service, Center for Musculoskeletal Surgery, Berlin, Germany Kazunori Yasuda, MD, PhD Professor and Chairman, Department of Sports Medicine and Joint Surgery, Hokkaido University School of Medicine, Sapporo, Japan Bing Yu, PhD Associate Professor, Division of Physical Therapy, Department of Allied Health Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina Charalampos G. Zalavras, MD Associate Professor, Department of Orthopaedic Surgery, Keck School of Medicine, University of Southern California; LACþUSC Medical Center, Los Angeles, California Bertram Zarins, MD Augustus Thorndike Clinical Professor of Orthopaedic Surgery, Harvard Medical School; Chief, Sports Medicine Service, Massachusetts General Hospital, Boston, Massachusetts

PART A ANATOMY, PHYSIOLOGY, BIOMECHANICS, EPIDEMIOLOGY

Anatomy and Biomechanics of the Anterior Cruciate Ligament INTRODUCTION Anterior cruciate ligament (ACL) reconstruction is the sixth most common procedure performed in orthopaedics, and it is estimated that between 75,000 and 100,000 ACL repair procedures are performed annually in the United States alone.1,2 The ACL has therefore been intensively studied, and outcomes of ACL surgery have received considerable attention. This has included research on surgical technique factors such as tunnel position, graft choices, and fixation methods, as well as postoperative rehabilitation protocols. Traditional single-bundle ACL reconstruction has focused on reconstruction of one portion of the ACL, the anteromedial (AM) bundle, and although outcomes are generally good, with success rates between 69% and 95%, there remains room for improvement.3,4 A prospective study of a cohort of ACL reconstructed patients 7 years after surgery revealed degenerative radiographic changes in 95% of patients, and only 47% were able to return to their previous activity level following ACL reconstruction.5 However, it should be noted that some studies of long-term follow-up have more encouraging results. Jarvela et al demonstrated tibiofemoral degenerative changes in only 18% of patients at 7 years follow-up post ACL reconstruction with bone–patella–bone grafts.6 In addition, Roe et al reported on a cohort of patients reconstructed with bone–patellar tendon–bone grafts and found an incidence of 45% with degenerative radiographic changes at 7 years follow-up, as well

as an incidence of 14% with degenerative changes in a group with hamstring grafts.7 A thorough review of the anatomy and biomechanics of the normal ACL reveals key points regarding its complex role in stabilization of the knee joint. Improved awareness of the anatomy and biomechanical properties of the normal ACL may lead to improvements in techniques for ACL reconstruction and an associated improvement in outcomes over traditional results. This chapter describes the normal anatomy of the two bundles of the ACL and reviews the biomechanical contributions of each bundle.

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CHAPTER

James S. Starman Mario Ferretti Timo Järvelä Anthony Buoncristiani Freddie H. Fu

ANTERIOR CRUCIATE LIGAMENT ANATOMY Historical Descriptions One of the earliest known descriptions of the human ACL was made around 3000 BC, written on an Egyptian papyrus scroll. During the Roman era, the earliest description of the ligament using its modern name was made by Claudius Galen of Pergamon (199–129 BC), who described the “ligamenta genu cruciate.” In 1543 the first known formal anatomical study of the human ACL was completed by Andreas Vesalius in his book De Humani Corporis Fabrica Libris Septum. Two bundles of the ACL were described for the first time in 1938 by Palmer et al, followed by Abbott et al in 1944 and Girgis et al in 1975.8–10 Each author described an AM bundle and a

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Anterior Cruciate Ligament Injury posterolateral (PL) bundle, named for the relative location of the tibial insertion sites of each bundle. More recently, in 1979 and again in 1991, Norwood et al and Amis et al, respectively, described a third bundle of the ACL anatomy, the intermediate (IM) bundle.11,12 Although it may be said that a two-bundle description of the ACL anatomy is an oversimplification of the complete anatomy, many studies have been based on this functional division, and it has been accepted as a reasonable way to understand the anatomy and biomechanics of the ligament. The IM bundle is most similar to the AM bundle in both anatomical and biomechanical considerations, and for the purposes of this chapter it is therefore considered as part of the AM bundle.

Anatomy of the Anteromedial and Posterolateral Bundles The ACL is a structure composed of numerous fascicles of dense connective tissue that connect the distal femur and the proximal tibia. Histological studies have demonstrated that a septum of vascularized connective tissue is present that separates the AM and PL bundles (Fig. 1-1). In addition, it has been shown that the histological properties of the ligament are variable at different stages in ACL development. At the time of fetal ACL development, the ACL is observed to be hypercellular with circular, oval, and fusiform-shaped cells. Later, in the adult ACL, the histology reveals a relatively hypocellular pattern with predominantly fibroblast cells with spindle-shaped nuclei.13,14 The ligament finds its origin on the medial surface of the lateral femoral condyle (LFC), runs an oblique course

within the knee joint from lateral and posterior to medial and anterior, and inserts into a broad area of the central tibial plateau. The cross-sectional area of the ligament varies significantly throughout its course from approximately 44 mm2 at the midsubstance to more than three times as much at both its origin and insertion.10,15,16 The total length of the ligament is approximately 31 to 38 mm and varies by as much as 10% throughout a normal range of motion.17

Anterior Cruciate Ligament Development ACL formation has been observed in fetal development as early as 8 weeks, corresponding to O'Rahilly stages 20 and 21.18,19 A leading hypothesis holds that the ACL originates as a ventral condensation of the fetal blastoma and gradually migrates posteriorly with the formation of the intercondylar space.20 The menisci are derived from the same blastoma condensation as the ACL, a finding that is consistent with the hypothesis that these structures function in concert.21 Another proposed mechanism of fetal ACL formation is from a confluence between ligamentous collagen fibers and fibers of the periosteum.22 Following the initial formation of the ligament, no major organizational or compositional changes are observed throughout the remainder of fetal development.19 Two distinct bundles of the ACL are present at 16 weeks of gestation (Fig. 1-2). In arthroscopy, the AM and PL bundles can also be appreciated, particularly with the knee held in 90 to 120 degrees of flexion (Fig. 1-3). Finally, cadaveric dissection also reveals two anatomical bundles of the ACL (Fig. 1-4). In summary, there is a considerable amount of interindividual variability with respect to the relative sizes of the AM and PL bundles, as seen in fetal, arthroscopic, and cadaveric studies; however, all individuals with an intact ACL have both bundles of ligament.

Insertion Site Anatomy

FIG. 1-1 Fetal anterior cruciate ligament, sagittal cut. Arrows indicate the septum of vascularized connective tissue dividing the anteromedial (AM) and posterolateral (PL) bundles.

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Anatomical studies have characterized the individual contributions of both the AM and PL bundles to the overall ACL architecture. Odensten and Gillquist described the femoral origin of the ACL as an ovoid area measuring 18 mm in length and 11 mm in width.23 Within this area, the AM bundle occupies a position located on the proximal portion of the medial wall of the LFC, and the PL bundle occupies a more distal position near the anterior articular cartilage surface of the LFC (Fig. 1-5, A). Harner et al studied the digitized origin and insertion of the AM and PL bundles in five cadavers and concluded that each bundle occupies approximately 50% of the total femoral origin, with crosssectional areas of 47  13 mm2 and 49  13 mm2 for AM and PL, respectively.16

Anatomy and Biomechanics of the Anterior Cruciate Ligament

1

FIG. 1-2 16-week fetus demonstrating two bundles of the anterior cruciate ligament with the knee in extension (A, sagittal view with medial femoral condyle removed) and flexion (B, frontal view). AM, Anteromedial; LFC, lateral femoral condyle; PL, posterolateral.

FIG. 1-3 Arthroscopic view of anteromedial (AM) and posterolateral (PL) bundles in 14-year-old female. Left knee, 110 degrees flexion. LFC, Lateral femoral condyle.

On the tibia, the insertions of the AM and PL bundles are located between the medial and lateral tibial spine over a broad area stretching as far posterior as the posterior root of the lateral meniscus. The full ACL insertion has been described as an oval area measuring 11 mm in diameter in the coronal plane and 17 mm in the sagittal plane.10,15,24 Within this area the AM bundle insertion can be found in an anterior

FIG. 1-4 Two distinct bundles of ACL present in cadaveric specimen. Left knee, 90 degrees flexion. AM, Anteromedial; LFC, lateral femoral condyle; PL, posterolateral.

and medial position, whereas the PL bundle insertion is located more posteriorly and laterally (Fig. 1-5, B). Posteriorly, fibers of the PL bundle are in close approximation to the posterior root of the lateral meniscus and, in some individuals, may attach to the meniscus itself (Fig. 1-6). The overall size of the tibial insertion is approximately 120% of the femoral origin; however, as is the case with the femoral origin, the two bundles 5

Anterior Cruciate Ligament Injury

FIG. 1-5 A, Femoral insertion sites of anteromedial (AM) and posterolateral (PL) bundles (right knee, medial femoral condyle removed). B, Tibial insertion sites of AM and PL bundles (right knee tibial plateau, menisci removed). Lat men, Lateral meniscus; MM, medial meniscus.

flexion. The femoral insertion sites are oriented vertically when the knee is in zero degrees, and the two bundles of the ACL are oriented in parallel (Fig. 1-7). As the knee moves into 90 degrees of flexion, the AM bundle insertion site on the femur rotates posteriorly and inferiorly, in contrast to the femoral insertion of the PL bundle, which rotates anteriorly and superiorly. This change in alignment of the insertion sites leads to a horizontal plane of insertions for the AM and PL bundle with the knee in 90 degrees of flexion (Fig. 1-8). The change in insertion site alignment causes the two bundles to twist around each other and become crossed. As the knee is flexed, the PL bundle can be seen anterior to the AM bundle at its femoral insertion (Fig. 1-9).

Tensioning Pattern FIG. 1-6 Posterolateral (PL) bundle tibial insertion is located just anterior to the posterior root of the lateral meniscus (Lat men). Left knee, arthroscopic view.

share approximately equal tibial insertion site areas: the AM bundle occupies 56  21 mm2, and the PL bundle occupies 53  21 mm2.16 The size and length of each bundle is also unique. The AM bundle is approximately 38 mm in length.10,15,17 The PL bundle has been less well studied. Kummer and Yamamoto measured the PL bundle in 50 cadavers and determined an average length of 17.8 mm.25 However, the AM and PL bundles have a similar diameter.

Crossing Pattern Based on their anatomical positions, the AM and PL bundles change alignment as the knee moves from extension to 6

The change in alignment of the AM and PL femoral insertion sites allows the ACL to twist around itself as it is moved through a complete range of motion. Clearly, this crossing pattern, along with the differences in the length of each bundle, has implications for the tensioning pattern of the overall ligament and each individual bundle. In a study by Gabriel et al, forces were measured in each bundle during an anterior load of 134N over several flexion angles, as well as for a combined rotatory load of 10 Nm valgus and 5 Nm internal tibial torque.26 The results showed that the PL bundle is tightest in extension (in situ force of 67  30N) and becomes relaxed as the knee is flexed, whereas the AM bundle is more relaxed in extension, and reaches a maximum tightness as the knee approaches 60 degrees of flexion (in situ forces of 90  17N).12,26 This tensioning pattern also can be observed grossly in cadaveric and arthroscopic views of the bundles (Fig. 1-10). The PL bundle is also observed to tighten during internal and external rotation.

Anatomy and Biomechanics of the Anterior Cruciate Ligament

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FIG. 1-7 Crossing pattern of anteromedial (AM) and posterolateral (PL) bundles. With the knee in extension, the AM and PL bundles are parallel (A, left knee, medial femoral condyle removed) and the insertion sites are oriented vertically (B).

FIG. 1-8 Crossing pattern of anteromedial (AM) and posterolateral (PL) bundles. With the knee in flexion, the AM and PL bundles are crossed (A, left knee, medial femoral condyle removed) and the insertion sites are oriented horizontally (B).

In summary, the ACL consists of two distinct bundles, the AM and PL bundles, and these bundles contribute synergistically to the stability of the knee. The alignment of the insertion sites of AM and PL on the femur allows the ligament to become crossed as the knee is flexed and can be observed as a vertical alignment of the femoral insertion sites during extension and a horizontal alignment of femoral insertion sites during flexion. We will now turn our attention to biomechanics for a review of the role of the ACL and the specific contributions of each bundle.

BIOMECHANICS Historical Studies The field of biomechanics has a long history, with the earliest known considerations dating back to Chinese and Greek literature around 400 to 500 BC. The first modern work in biomechanics was completed during the 1500s to 1700s by well-known figures such as Galileo, DaVinci, Borelli, Hooke, and Newton. Orthopaedic biomechanics was 7

Anterior Cruciate Ligament Injury

FIG. 1-9 Arthroscopic view and computer model of anteromedial (AM) and posterolateral (PL) bundle crossing pattern in extension (top) and flexion (bottom). The PL bundle is obscured in extension but becomes visible in flexion as it moves anteriorly on the femoral side. LFC, Lateral femoral condyle.

FIG. 1-10 Arthroscopic views of an anterior cruciate ligament (ACL)-injured left knee with an intact posterolateral (PL) bundle and torn anteromedial bundle (removed). In extension, the PL bundle is tensioned maximally and appears taut (A), and in 90 degrees flexion, the PL bundle is more relaxed (B).

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Anatomy and Biomechanics of the Anterior Cruciate Ligament initially advanced during the 1940s and 1950s by the work of Eadweard Muybridge, Arthur Steindler, Verne Inman, Henry Lissner, and A. H. Hirsch. Since the 1960s, the information learned from biomechanical studies in orthopedics has been applied to refine clinical treatment approaches.

Anterior-Posterior Translation Control The dynamic nature of the two bundles of the ACL during knee flexion demonstrates the complex role of the ACL in stabilization of the knee joint. However, initial biomechanical studies of the ACL focused mainly on its function of resisting anterior tibial translation.27,28 From this work we know that the in situ forces of the ACL vary considerably during a normal range of motion of the knee joint. With a 110N anterior tibial load applied, the ACL demonstrates high in situ forces between 0 and 30 degrees flexion, with a maximum occurring at 15 degrees. In situ forces are at their lowest point between 60 and 90 degrees, with a minimum occurring at 90 degrees. As mentioned earlier, recent studies have also been completed to evaluate the individual roles of each bundle of the ACL in anterior-posterior translation. These studies have shown that the AM bundle has relatively constant levels of in situ forces during knee flexion, whereas the PL bundle is more variable, with high in situ forces at 0, 15, and 30 degrees of flexion but rapidly decreasing in situ forces beyond this angle.28

Rotational Stability Clinical experience has suggested that biomechanical considerations of anterior-posterior translation alone do not correlate with subjective evaluations of knee stability and that a more complete evaluation of the role of rotational stability is relevant.29 Therefore, in recent years closer attention has been given to the rotational stabilizing function of the ACL.26,30,31 Included in the study by Gabriel et al was an analysis of a combined rotatory load of 10 Nm valgus and 5 Nm internal tibial torque at 15 and 30 degrees flexion. For the PL bundle, in situ forces of 21N were recorded at 15 degrees and 14N at 30 degrees. For the AM bundle, in situ forces were 30N and 35N, respectively. This demonstrates that the both the AM and PL bundles contribute to rotational stability of the knee at these angles. In addition to biomechanical studies, recent studies using in vivo kinematics analysis have assessed rotational stability in the ACL during various functional activities such as walking, running, and cutting.32–34 Andriacchi et al studied the in vivo kinematics of normal and ACL-deficient subjects during four phases of walking and determined that

1

an ACL-deficient knee is positioned differently than a normal knee. During walking, the intact ACL maintains a balance of rotation during the interval of swing phase to heel strike. However, in the ACL-deficient knee, an increased internal rotation occurs between these phases of walking, which is maintained through the stance phase.30 A study of running and cutting in ACL-deficient patients demonstrated normal anterior-posterior stability during running but abnormal rotational movements compared with subjects with an intact ACL.34 Finally, a magnetic resonance imaging (MRI)-based study of the in vivo kinematics of the normal ACL during weight-bearing knee flexion has demonstrated that several components of ACL kinematics change during weightbearing knee flexion. First, as the flexion angle increases, axial rotation (or twist) of the ACL increases as well. At full extension the ACL is internally twisted by approximately 10 degrees; however, this increases to approximately 20 degrees when the knee is moved to 30 degrees flexion, and it increases to approximately 40 degrees with the knee at 60 to 90 degrees flexion. Second, the orientation of the ligament within the joint space changes with the flexion angle. As the knee flexion angle increases, so does the lateral angulation of the ligament. Therefore, the ligament may possess a lateral force component, functioning to constrain internal tibial rotation.32,33 In summary, the ACL provides an important part of rotational stability during both low- and high-demand activities by helping to maintain the normal position of the tibiofemoral contact, a role that is shared by both bundles of the ligament.

Biomechanics Considerations in Anterior Cruciate Ligament Surgery Based on the aforementioned research into the role of rotational stability, work has been completed to assess the ability of different surgical techniques in restoring both anteriorposterior translation of the knee and rotational stability. Yagi et al performed a study comparing a single-bundle reconstruction with the femoral tunnel placed at the 11- or 1-o'clock position with anatomical double-bundle ACL reconstruction and the femoral tunnels placed based on the insertion site anatomy of the transected ACL.35 In this study, the doublebundle ACL reconstruction was better able to resist anterior tibial translation at full extension and 30 degrees flexion, compared with the single-bundle technique. Additionally, when a combined internal tibial and valgus torque was applied at 15 and 30 degrees flexion, the double-bundle ACL reconstruction had a response closer to the intact ACL compared with the single-bundle technique. 9

Anterior Cruciate Ligament Injury Yamamoto et al compared the double-bundle ACL reconstruction with a lateral single-bundle reconstruction, with the femoral tunnel placed approximately at a 10-o'clock position for the right knee.36 The double-bundle anatomical reconstruction better restored the anterior tibial translation at 60 degrees and 90 degrees flexion when compared with the single-bundle technique.36 Finally, Tashman et al performed an in vivo kinematics analysis of normal and single-bundle reconstructed knees.31 Subjects with a normal ACL were compared with a group of single-bundle ACL reconstructed patients to evaluate anterior-posterior translation and knee rotation during downhill jogging. Single-bundle ACL reconstructed patients had fully restored anterior-posterior translation as compared with subjects with a normal ACL but were found to lack normal rotational kinematics.31 Because the singlebundle reconstruction is an approximation of the position of the AM bundle, it can be concluded that part of the rotational stability is derived from the actions of the PL bundle. In summary, Yagi et al and Yamamoto et al have demonstrated that normal anterior-posterior translation may be restored using traditional single-bundle reconstruction techniques. However, it is not possible to restore rotational stability using this approach.35,36 In addition, Tashman et al have shown that single-bundle reconstruction is not capable of restoring normal rotational kinematics.36 Anatomical double-bundle reconstruction, in contrast, offers an opportunity to restore both components of normal knee stability as demonstrated in cadaveric biomechanics studies, and it is possible that this will soon be demonstrated in an in vivo kinematics model as well.35,36

CONCLUSION The anatomy of the ACL shows that the ligament consists of two distinct and functional bundles, the AM and PL bundles. These two bundles have unique points of attachment in the knee, and this leads to their complex spatial relationship throughout knee flexion, as well as their different roles in biomechanics and knee stability. It is important to take the anatomical properties of the ACL into consideration when performing ACL surgery. This may lead to a more accurate restoration of knee kinematics to the native state and improvements in long-term outcomes. However, although the current body of knowledge of the anatomy and biomechanics of the ACL is extensive, it remains incomplete. Future work in areas such as in vivo kinematics will allow for a more complete understanding of rotational stability and knee motion during complex movements.

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References 1. ABOS, Diplomat 2004. www.abos.org 2. Griffin LY, Agel J, Albohm MJ, et al. Non-contact anterior cruciate ligament injuries: risk factors and prevention strategies. J Am Acad Orthop Surg 2000;8:141–150. 3. Yunes M, Richmond JC, Engels EA, et al. Patellar versus hamstring tendons in anterior cruciate ligament reconstruction: a meta-analysis. Arthroscopy 2001;17:248–257. 4. Freedman KB, D'Amato MJ, Nedeff DD, et al. Arthroscopic anterior cruciate ligament reconstruction: a metaanalysis comparing patellar tendon and hamstring tendon autografts. Am J Sports Med 2003;31:2–11. 5. Fithian DC, Paxton EW, Stone ML, et al. Prospective trial of a treatment algorithm for the management of the anterior cruciate ligamentinjured knee. Am J Sports Med 2005;33:335–346. 6. Jarvela T, Paakkala T, Kannus P, et al. The incidence of patellofemoral osteoarthritis and associated findings seven years after anterior cruciate ligament reconstruction with a bone-patellar tendon-bone autograft. Am J Sports Med 2001;29:18–24. 7. Roe J, Pinczewski LA, Russell VJ, et al. A seven year follow-up of patellar tendon and hamstring tendon grafts for arthroscopic anterior cruciate ligament reconstruction. Am J Sports Med 2005;33:1337–1345. 8. Palmer I. On the injuries to the ligaments of the knee joint. Acta Chir Scand 1938;91:282. 9. Abbott LC, Saunders JB, Bost FC, et al. Injuries to the ligaments of the knee joint. J Bone Joint Surg Am 1944;26A:503–521. 10. Girgis FG, Marshall JL, Al Monajem ARS. The cruciate ligaments of the knee joint. Clinic Orthop 1975;106:216–231. 11. Norwood LA, Cross MJ. Anterior cruciate ligament: functional anatomy of its bundles in rotary instabilities. Am J Sports Med 1979;7:23. 12. Amis AA, Dawkins GPC. Functional anatomy of the anterior cruciate ligament. Fibre bundle actions related to ligament replacement and injuries. J Bone Joint Surg Br 1991;73:260–267. 13. Shino K, Inoue M, Horibe S, et al. Maturation of allografts tendons transplanted into the knee. An arthroscopic and histological study. J Bone Joint Surg Br 1988;70:556–560. 14. Falconiero RP, DiStefano VJ, Cook TM. Revascularization and ligamentization of autogenous anterior cruciate ligament grafts in humans. Arthroscopy 1998;14:197–205. 15. Arnoczsky SP. Anatomy of the anterior cruciate ligament. Clin Orthop 1983;172:19–25. 16. Harner CD, Baek GH, Vogrin TM, et al. Quantitative analysis of human cruciate ligament insertions. Arthroscopy 1999;15:741–749. 17. Fu FH, Bennett CH, Lattermann C, et al. Current trends in anterior cruciate ligament reconstruction. Part 1: biology and biomechanics of reconstruction. Am J Sports Med 1999;27:821–830. 18. O'Rahilly R. The early prenatal development of the human knee joint. J Anat 1951;85:166–170. 19. Gardner E, O'Rahilly R. The early development of the knee joint in staged human embryos. J Anat 1968;102:289–299. 20. Ellison AE, Berg EE. Embryology, anatomy, and function of the anterior cruciate ligament. Orthop Clin North Am 1985;16:3–14. 21. Galleazzi R. Clinical and experimental study of the semilunar cartilage of the knee joint. J Bone Joint Surg 1929;9:515. 22. Behr CT, Potter HG, Paletta GA, Jr. The relationship of the femoral origin of the anterior cruciate ligament and the distal femoral physeal plate in the skeletally immature knee. An anatomic study. Am J Sports Med 2001;29:781–787. 23. Odensten M, Gillquist J. Functional anatomy of the anterior cruciate ligament and a rationale for reconstruction. J Bone Joint Surg Am 1985;67:257–262. 24. Petersen W, Tillmann B. Anatomy and function of the anterior cruciate ligament. Orthopade 2002;31:710–718.

Anatomy and Biomechanics of the Anterior Cruciate Ligament 25. Kummer B, Yamamoto Y. [Funktionelle Anatomie der Kreuzbaender]. Arthroskopie 1988;1:2–10. 26. Gabriel MT, Wong EK, Woo SL, et al. Distribution of in situ forces in the anterior cruciate ligament in response to rotatory loads. J Orthop Res 2004;22:85–89. 27. Takai S, Woo SL-Y, Livesay GA, et al. Determination of the in situ loads on the human anterior cruciate ligament. J Orthop Res 1993;11:686–695. 28. Sakane M, Fox RJ, Woo SL-Y, et al. In situ forces in the anterior cruciate ligament and its bundles in response to anterior tibial loads. J Orthop Res 1997;15:285–293. 29. Kocher MS, Steadman JR, Briggs KK, et al. Relationships between objective assessment of ligament stability and subjective assessment of symptoms and function after anterior cruciate ligament reconstruction. Am J Sports Med 2004;32:629–634. 30. Andriacchi TP, Dyrby CO. Interactions between kinematics and loading during walking for the normal and ACL deficient knee. J Biomech 2005;38:293–298.

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31. Tashman S, Collon D, Anderson K, et al. Abnormal rotational knee motion during running after anterior cruciate ligament reconstruction. Am J Sports Med 2004;32:975–983. 32. Li G, DeFrate LE, Rubash HE, et al. In vivo kinematics of the ACL during weight-bearing knee flexion. J Orthop Res 2005;23:340–344. 33. Li G, DeFrate LE, Sun H, et al. In vivo elongation of the anterior cruciate ligament and posterior cruciate ligament during knee flexion. Am J Sports Med 2004;32:1415–1420. 34. Waite JC, Beard DJ, Dodd CA, et al. In vivo kinematics of the ACLdeficient limb during running and cutting. Knee Surg Sports Traumatol Arthrosc 2005;13:377–384. 35. Yagi M, Wong EK, Kanamori A, et al. Biomechanical analysis of an anatomic anterior cruciate ligament reconstruction. Am J Sports Med 2002;30:660–666. 36. Yamamoto Y, Hsu Y, Woo SL, et al. Knee stability and graft function after anterior cruciate ligament reconstruction: a comparison of a lateral and an anatomical femoral tunnel placement. Am J Sports Med 2004;32:1825–1832.

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2

CHAPTER

William E. Garrett, Jr. Bing Yu

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Mechanisms of Noncontact Anterior Cruciate Ligament Injuries As in the prevention of other injuries in sports, understanding injury mechanisms is a key component of preventing noncontact anterior cruciate ligament (ACL) injuries.1 The research effort to determine risk factors of sustaining noncontact ACL injuries is increasing as the concerns of increased incidents and cost for treatment, as well as serious consequences of noncontact ACL injuries, are growing. Prospective cohort studies are commonly used in epidemiological research designs for determining risk factors of injuries and diseases2 and are being used to determine risk factors of sustaining noncontact ACL injuries.3 The results of epidemiological studies with cohort designs, however, are descriptive in nature and lack cause-and-effect relationship between identified risk factors and the injury.2 Without a good understanding of the injury mechanisms, the risk factors of sustaining noncontact ACL injuries identified from epidemiological studies could be misinterpreted and could lead to the selection of nonoptimal injury prevention programs. Injuries of the ACL frequently occur in athletic movements such as stopping or quickly changing directions. These kinds of movements often are awkward and off-balance maneuvers. Video analysis often shows a hard landing with the knee near full extension in these movements as the athlete experienced a sensation of the knee collapsing into a valgus position. The quadriceps muscles are likely to be the major source of the anterior shear force that causes the rupture of the ACL in these movements. However, we have not been accustomed to considering the fact that our own muscles can create injuries. Although a

valgus moment applied to the knee can create enough deformation to cause an injury of the ACL, few noncontact ACL injuries involve serious injuries to the medial collateral ligament (MCL) that would occur if the knee sustained sufficient valgus moment loading to injure the ACL. This chapter will examine biomechanical studies relating to ACL injury and explore strains induced by the quadriceps muscles near full knee extension and by valgus moment loading. Mechanically, ACL injury occurs when an excessive tension force is applied on the ACL. A noncontact ACL injury occurs when a person self-generates great forces or moments at the knee that applied excessive loading on the ACL. An understanding of the mechanisms of ACL loading during active human movements, therefore, is crucial for understanding the mechanisms of noncontact ACL injuries and risk factors of sustaining noncontact ACL injuries. Berns et al4 investigated the effects of combined knee loading on ACL strain on 13 cadaver knees. The strain of the anteromedial (AM) bundle of the ACL was recorded using liquid mercury strain gauges at 0 and 30 degrees knee flexion. The results of this study showed that anterior shear force on the proximal end of the tibia was the primary determinant of the strain in the AM bundle of the ACL, whereas neither pure knee internal-external rotation moment nor pure knee valgus-varus moment had significant effects on the strain of the AM bundle of the ACL. The results of this study further showed that anterior shear force at the proximal end of the tibia combined with a knee

Mechanisms of Noncontact Anterior Cruciate Ligament Injuries valgus moment resulted in a significantly greater strain in the AM bundle of the ACL than did the anterior shear force at the proximal end of the tibia alone. Markolf et al5 also investigated effects of anterior shear force at the proximal end of the tibia and knee valgus, varus, internal rotation, and external rotation moments on the ACL loading of cadaver knees. A 100N anterior shear force and 10-Nm knee valgus, varus, internal rotation, and external rotation moments were added to cadaver knees. The ACL loading was recorded as the knee was extended from 90 degrees flexion to 5 degrees hyperextension. The results of this study showed that an anterior shear force on the tibia generated significant ACL loading, whereas the knee valgus, varus, and internal rotation moments also generated significant ACL loading only when the ACL was loaded by the anterior shear force at the proximal end of the tibia. The results of this study further showed that the ACL loading due to the anterior shear force combined with either a valgus or a varus moment to the knee was greater than that due to the anterior shear force alone, whereas the ACL loading due to the anterior shear force combined with a knee external rotation moment was lower than that due to anterior shear force alone. The knee valgus and external rotation moment loading are elements of dynamic valgus that many current ACL injury prevention programs are trying to avoid.3 The results of the study by Markolf et al5 also showed that ACL loading due to the combined knee varus and internal rotation moment loading was greater than that due to either knee varus moment loading or internal rotation moment loading alone and that the ACL loading due to combined knee valgus and external rotation moment loading was lower than that due to either knee valgus or external rotation moment loading alone. Finally, the results of this study showed that the ACL loading due to the anterior shear force and knee valgus, varus, and internal rotation moments increased as the knee flexion angle decreased. Fleming et al6 studied the effects of weight bearing and tibia external loading on ACL strain. They implanted a differential variable reluctance transducer to the AM bundle of the ACL of 11 subjects. ACL strains were measured in vivo when a subject's leg was attached to a knee loading fixture that allowed independent application of anteriorposterior shear force, valgus-varus moments, and internalexternal rotation moments to the tibia and simulation of weight-bearing conditions. The anterior shear force was applied on the proximal end of the tibia from 0N to 130N in 10-N increments. The valgus-varus moments were applied to the knee from 10 Nm to 10 Nm in 1-Nm increments. The internal-external rotation moments were applied to the knee from 9 Nm to 9 Nm in 1-Nm increments. The knee flexion angle was fixed at 20 degrees during the test. The results of this study showed that ACL strain significantly

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increased as the anterior shear force at the proximal end of the tibia and the knee internal rotation moment increased, whereas knee valgus-varus and external rotation moments had little effects on ACL strain under the weight-bearing condition. The previously mentioned studies consistently showed that the anterior shear force at the proximal end of the tibia is a major contributor to ACL loading, whereas the knee valgus, varus, and internal rotation moments may increase ACL loading when an anterior shear force at the proximal end of the tibia is applied. According to these ACL loading mechanisms, a small knee flexion angle, a strong quadriceps muscle contraction, or a great posterior ground reaction force can increase ACL loading. Quadriceps muscles are the major contributor to the anterior shear force at the proximal end of the tibia through the patella tendon. DeMorat et al7 demonstrated that a 4500-N quadriceps muscle force could create ACL injuries at 20 degrees knee flexion. Eleven cadaver knee specimens were fixed to a knee simulator and loaded with 4500-N quadriceps muscle force. Quadriceps muscle contraction tests at 400 N (Q-400 tests) and KT-1000 tests were performed before and after the 4500-N quadriceps muscle force loading. Tibia anterior translations were recorded during the Q-400 and KT-1000 tests. All cadaver knee specimens were dissected after all tests to determine the ACL injury states. Six of the 11 specimens had confirmed ACL injuries (three complete ACL tears and three partial tears). All specimens showed increased tibia anterior translation in Q-400 and KT-1000 tests. The result of this study also showed that quadriceps muscle contraction caused not only tibia anterior translation but also tibia internal rotation. Decreasing knee flexion angle increases the anterior shear force at the proximal end of the tibia by increasing the patella tendon–tibia shaft angle. With a given quadriceps muscle force, the anterior shear force at the proximal end of the tibia is determined by the patella tendon–tibia shaft angle, defined as the angle between the patella tendon and the longitudinal axis of the tibia.8 With a given quadriceps muscle force, the greater the patella tendon–tibia shaft angle, the greater the anterior shear force on the tibia. Nunley et al8 studied the relationship between the patella tendon–tibia shaft angle and knee flexion angle with weight bearing. Ten male and 10 female university students without known history of lower extremity injuries were recruited as the subjects. Sagittal plane x-ray films were taken for each subject at 0, 15, 30, 45, 60, 75, and 90 degrees knee flexion, bearing 50% of body weight. Patella tendon–tibia shaft angles were measured from the x-ray films. Regression analyses were performed to determine the relationship between patella tendon–tibia shaft angle and knee flexion angle and to compare the relationship between genders. The results 13

Anterior Cruciate Ligament Injury showed that the patella tendon–tibia shaft angle was a function of the knee flexion angle, with the patella tendon–tibia shaft angle increasing as the knee flexion angle decreased, and that on average the patella tendon–tibia shaft angle was 4 degrees greater in females than in males. The relationship between the patella tendon–tibia shaft angle and knee flexion angle obtained by Nunley et al8 was consistent with those from other studies on the patella tendon–tibia shaft angle under non–weight-bearing conditions.9–11 Decreasing the knee flexion angle also increases ACL loading by increasing the ACL elevation angle and deviation angle, defined as the angle between the longitudinal axis of the ACL and the tibia plateau and the angle between the projection of the longitudinal axis of the ACL on the tibia plateau and the posterior direction of the tibia, respectively.12 The resultant force along the longitudinal axis of the ACL equals the anterior shear force on the ACL divided by the cosines of the ACL elevation and deviation angles. The greater the ACL elevation and deviation angles, the greater the ACL loading with a given anterior shear force on the ACL. Li et al12 determined the in vivo ACL elevation and deviation angles as functions of the knee flexion angle with weight bearing. Five young and healthy volunteers were recruited as the subjects. The ACL elevation and deviation angles at 0, 30, 60, and 90 degrees knee flexion with weight bearing were obtained using individualized dual-orthogonal fluoroscopic images and magnetic resonance imaging (MRI)-based, three-dimensional (3D) models. The results of this study showed that both the ACL elevation and deviation angles increased as the knee flexion angle decreased. Several studies show that ACL loading increases as the knee flexion angle decreases. Arms et al13 studied the biomechanics of ACL rehabilitation and reconstruction and found that quadriceps muscle contraction significantly strained the ACL from 0 to 45 degrees knee flexion but did not strain the ACL when knee flexion was greater than 60 degrees. Beynnon et al14 measured the in vivo ACL strain during rehabilitation exercises and found that isometric quadriceps muscle contraction resulted in a significant increase in ACL strain at 15 and 30 degrees knee flexions but resulted in no change in ACL strain relative to the relaxed muscle condition at 60 and 90 degrees knee flexion. Li et al15,16 investigated the quadriceps and hamstring muscle loading on ACL loading and showed that the in situ ACL loading increased as the knee flexion angle decreased when quadriceps muscles were loaded, regardless of the hamstring muscle loading conditions. Literature also shows that individuals at high risk of sustaining noncontact ACL injuries have a smaller knee flexion angle during athletic tasks than do individuals at low risk. Epidemiological studies show that female athletes are at higher risk of sustaining noncontact ACL injuries than 14

their male counterparts.17–24 Recent biomechanical studies demonstrated that female recreational athletes exhibited small knee flexion angles in running, jumping, and cutting tasks.25,26 Studies also demonstrate that female adolescent athletes had a sharply increased ACL injury rate after age 13 years.27,28 A recent biomechanical study showed that female adolescent soccer players started decreasing their knee flexion angle during a stop-jump task after age 13 years.29 Taken together, these results suggest that small knee flexion angle during landing tasks may be a risk factor of sustaining noncontact ACL injuries. Increasing peak posterior ground reaction forces during athletic tasks increases ACL loading by inducing an increased quadriceps muscle contraction. A posterior ground reaction force creates a flexion moment relative to the knee, which needs to be balanced by a knee extension moment generated by the quadriceps muscles.30 As previously described, the quadriceps muscle contraction adds an anterior shear force on the proximal end of the tibia through the patella tendon. The greater the posterior ground reaction force, the greater the quadriceps muscle force and the greater the ACL loading.30 Cerulli et al31 and Lamontagne et al32 recently recorded in vivo ACL strain in a hop-landing task. A differential variable reluctance transducer was implemented on the middle portion of the AM bundle of the ACLs of three subjects through surgical procedures. Subjects then performed the hop-landing task in a biomechanics laboratory. Force plate, electromyography (EMG), and in vivo ACL strain were recorded simultaneously. The results of this study showed that the peak ACL strain occurred at the impact peak vertical ground reaction force shortly after initial contact between foot and ground. Yu et al30 demonstrated that peak impact vertical and posterior ground reaction forces occurred essentially at the same time. Taken together, these results suggest that a hard landing with a great impact posterior ground reaction force may be a risk factor of sustaining noncontact ACL injuries. Literature shows that individuals at a high risk of sustaining noncontact ACL injuries have greater peak posterior ground reaction forces in athletic tasks. Chappell et al26 studied the lower extremity kinetics as well as kinematics of university-age recreational athletes during landings of stop-jump tasks. Their results showed that female recreational athletes had greater peak resultant proximal tibia anterior shear force and knee joint resultant extension moment during landings of stop-jump tasks than did male recreational athletes. Yu et al studied the immediate effects of a newly designed knee brace with a constraint to knee extension during a stop-jump task.29–29b Their results showed that the university-age female recreational athletes had greater peak posterior ground reaction force during the landing of the stop-jump task than did their male

Mechanisms of Noncontact Anterior Cruciate Ligament Injuries counterparts. Yu et al30 showed that the resultant peak proximal tibia anterior shear force was positively correlated to the peak posterior ground reaction force. Hamstring co-contractions protecting the ACL have been a longstanding clinical concept because hamstring muscles provide a posterior shear force on the tibia that is supposed to reduce the anterior shear force on the tibia from the patellar tendon and thus unload the ACL. Recent scientific studies, however, did not support this concept. Li et al15 showed in a cadaver study that hamstring cocontraction did not significantly decrease tibia anterior translation when the knee flexion angle was less than 30 degrees. Beynnon et al14 found that the isometric hamstring co-contraction of the hamstring muscles did reduce in vivo ACL strain between 15 and 60 degrees knee flexion. Kingma et al33 found that hamstring muscle activation increased only 1.3 to 2.0 times, whereas knee extension moment increased 2.7 to 3.4 times with a knee flexion angle between 5 and 50 degrees, which did not suggest a hamstring recruitment pattern to reduce the ACL loading. O'Connor,34 Pandy et al,35 and Yu et al29 all studied ACL loading using a modeling and computer simulation approach and showed that the hamstring muscles did not reduce ACL loading at all when the knee flexion angle was small. Although biomechanical studies showed that the knee valgus moment was not a major mechanism of ACL loading, a recent epidemiological study by Hewett et al3 reported that external knee valgus moment in a vertical drop landing–jump task was a predictor of ACL injuries. A total of 205 high school soccer, basketball, and volleyball players were followed for three competition seasons. Knee flexion and valgus angles at initial foot contact with the ground and the maximum knee flexion and valgus angles and maximum moments during the stance phase of the vertical drop landing–jump task were recorded prospectively for every subject. A total of nine subjects sustained ACL injuries after three competition seasons. The results of this study showed that knee abduction angle at landing was 8 degrees greater in ACL-injured than in uninjured athletes and that ACL-injured athletes had a 2.5 times greater peak external knee valgus moment and 20% higher peak vertical ground reaction force than did uninjured athletes. The results further showed that peak external knee valgus moment predicted ACL injury status with 73% specificity, 78% sensitivity, and a predictive R2 value of 0.88. The results of this study appear to suggest an association between knee valgus angle and moment with ACL injuries. However, we may have to be cautious when interpreting the association of knee valgus angle and moment with noncontact ACL injuries observed in the study by Hewett et al.3 The observed preinjury knee valgus moments of the nine subjects who suffered ACL injuries in this study

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were less than 0.12 Nm/body weight/standing height. The average body weight and stranding height of the injured subjects in this study were 62 kg and 1.68 m, respectively. This means that the preinjury knee valgus moments of the nine injured subjects in this study were less than 12.5 Nm. These knee valgus moment loadings were similar to those in the studies by Berns et al,4 Markolf et al,5 and Fleming et al,6 which demonstrated that knee valgus loading did not significantly affect ACL loading unless a significant proximal tibia anterior shear force was applied. Furthermore, several other studies in the current literature demonstrate that knee valgus moment loading alone cannot injure the ACL when the MCL is intact. Bendjaballah et al36 studied the effects of knee valgus-varus moment loading on cruciate and collateral ligament loadings using a finite element model. Their results suggest that cruciate ligaments are not major valgus-varus moment loading bearing structures when collateral ligaments are intact. Matsumoto et al37 investigated the roles of the ACL and MCL in preventing knee valgus instability using cadaver knees. Their results demonstrate that the MCL is the major structure to stop medial knee space opening. Mazzocca et al38 tested the effect of knee valgus loading on MCL and ACL injuries. They found that the response of the ACL strain to knee valgus moment loading was minimal when the MCL was intact but significantly increased after the MCL rupture began due to knee valgus moment loading. Their results show that the ACL still had about 60% of its original strength after complete MCL ruptures with medial knee space openings greater than 15 mm due to knee valgus moment loading. This study clearly demonstrates that a complete ACL rupture due to knee valgus moment loading without a complete MCL rupture (grade III injury) is unlikely, whereas clinical observations show that the majority of noncontact ACL injuries do not have significant MCL injuries. A recent study by Fayad et al39 showed that only 5 of a total of 84 contact and noncontact ACL injuries had complete MCL ruptures. Taken together, these studies suggest that knee valgus moment loading alone is not likely to be a major ACL loading mechanism that can result in ACL rupture or a major risk factor of sustaining noncontact ACL injuries. More scientific studies are needed before we can confidently interpret the association of knee valgus angle and moment with noncontact ACL injuries as a sole risk factor of sustaining noncontact ACL injuries. In summary, the current literature clearly suggests that sagittal plane biomechanics are the major mechanism of ACL loading. Decreased knee flexion angle and increased quadriceps muscle force and posterior ground reaction force causing an increased knee extension moment are requirements for increased ACL loading. Although the external knee valgus moment has been demonstrated to be associated 15

Anterior Cruciate Ligament Injury with ACL injuries, the current literature contains no evidence that knee valgus-varus and internal-external rotation moments can produce noncontact ACL injuries in and of themselves without these high sagittal plane forces.

References 1. Bahr R, Krosshaug T. Understanding injury mechanisms: a key component of preventing injuries in sport. Br J Sports Med 2005;39: 324–329. 2. Portney LG, Watkins MP. Foundations of clinical research: applications to practice, ed 2. Upper Saddle River, NJ, 2000, Prentice Hall Health. 3. Hewett TE, Myer GD, Ford KR, et al. Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes: a prospective study. Am J Sports Med 2005;33:492–501. 4. Berns GS, Hull ML, Paterson HA. Strain in the anterior medial bundle of the anterior cruciate ligament under combined loading. J Orthop Res 1992;10:167–176. 5. Markolf KL, Burchfield DM, Shapiro MM, et al. Combined knee loading states that generate high anterior cruciate ligament forces. J Orthop Res 1995;13:930–935. 6. Fleming BC, Renstrom PA, Beynnon BD, et al. The effect of weightbearing and external loading on anterior cruciate ligament strain. J Biomech 2001;34:163–170. 7. DeMorat G, Weinhold P, Blackburn T, et al. Aggressive quadriceps loading can induce noncontact anterior cruciate ligament injury. Am J Sports Med 2004;32:477–483. 8. Nunley RM, Wright D, Renner JB, et al. Gender comparison of patellar tendon tibial shaft angle with weight bearing. Res Sports Med 2003;11:173–185. 9. Smidt JG. Biomechanical analyses of knee flexion and extension. J Biomech 1973;6:79–82. 10. Buff HU, Jones LC, Hungerford DS. Experimental determination of forces transmitted through the patella-femoral joint. J Biomech 1988;21:17–23. 11. vanEijden TMGJ, De Boer W, Weijs WA. The orientation of the distal part of the quadriceps femoris muscle as a function of the knee flexion-extension angle. J Biomech 1985;18:803–809. 12. Li G, DeFrate LE, Rubash HE, et al. In vivo kinematics of the ACL during weight-bearing knee flexion. J Orthop Res 2005;23:340–344. 13. Arms SW, Pope MH, Johnson RJ, et al. The biomechanics of anterior cruciate ligament rehabilitation and reconstruction. Am J Sports Med 1984;12:8–18. 14. Beynnon BD, Fleming BC, Johnson RJ, et al. Anterior cruciate ligament strain behavior during rehabilitation exercises in vivo. Am J Sports Med 1995;23:24–34. 15. Li G, Rudy TW, Sakane M, et al. The importance of quadriceps and hamstring muscle loading on knee kinematics and in-situ forces in the ACL. J Biomech 1999;32:395–400. 16. Li G, Zayontz S, Most E, et al. In situ forces of the anterior and posterior cruciate ligaments in high knee flexion: an in vitro investigation. J Orthop Res 2004;22:293–297. 17. Ferretti A, Papandrea P, Conteduca F, et al. Knee ligament injuries in volleyball players. Am J Sports Med 1992;20:203–207. 18. Paulos LE. Why Failures Occur Symposium: revision ACL surgery, American Orthopaedic Society for Sports Medicine Eighteenth Annual Meeting, San Diego, CA, July 1992. 19. Malone TR, Hardaker WT, Garrett WE, et al. Relationship of gender to anterior cruciate ligament injuries in intercollegiate basketball players. J South Orthop Assoc 1993;2:36–39. 20. Pearl AJ. The athletic female, Champaign, IL, 1993, Human Kinetics, pp 302–303. 21. Irelan ML. Special concerns of the female athlete. Sports injuries: mechanism, prevention, and treatment, ed 2. Philadelphia, 1994, Williams & Wilkins, pp 153–187.

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22. Lindenfeld TN, Schmitt DJ, Hendy MP, et al. Incidence of injury in indoor soccer. Am J Sports Med 1994;22:354–371. 23. Woodford-Rogers B, Cyphert L, Denegar CR. Risk factors for anterior cruciate ligament injury in high school and college athletes. J Athl Train 1994;29:343–346. 24. Arendt E, Dick R. Knee injury patterns among men and women in collegiate basketball and soccer. NCAA data and review of literature. Am J Sports Med 1995;23:694–701. 25. Malinzak RA, Colby SM, Kirkendall DT, et al. A comparison of knee joint motions patterns between men and women in selected athletic maneuvers. Clin Biomech 2001;16:438–445. 26. Chappell JD, Yu B, Kirdendall DT, et al. A comparison of knee kinetics between male and female recreational athletes in stop-jump tasks. Am J Sports Med 2002;30:261–267. 27. Yu B, Kirkendall DT, Taft TN, et al. Lower extremity motor controlrelated and other risk factors for noncontact anterior cruciate ligament injuries. Instruct Course Lect 2002;51:315–324. 28. Shea KG, Pfeiffer R, Wang JH, et al. Anterior cruciate ligament injury in pediatric and adolescent soccer players: an analysis of insurance data. J Pediatr Orthop 2004;24:623–628. 29. Yu B, McClure SB, Onate JA, et al. Age and gender effects on lower extremity kinematics of youth soccer players in a stop-jump task. Am J Sports Med 2005;33:1356–1364. 29a. Yu B, Herman D, Preston J, et al. Immediate effects of a knee brace with a constraint to knee extension on knee kinematics and ground reaction forces in a stop-jump task. Am J Sports Med 2004;32:1136–1143. 29b. Yu B, Lin CF, Garrett WE. Lower extremity biomechanics during the landing of a stop-jump task. Clin Biomech 2006;21:297–305. 30. Yu B, Chappell JD, Garrett WE. Authors’ response to letter to the editor. Am J Sports Med 2006;34:312–315. 31. Cerulli G, Benoit DL, Lamontagne M, et al. In vivo anterior cruciate ligament strain behavior during a rapid deceleration movement: case report. Knee Surg Sports Traumatol Arthrosc 2003;11:307–311. 32. Lamontagne M, Benoit DL, Ramsey DK, et al. What can we learn from in vivo biomechanical investigation of lower extremity? Proc XXIII Int Symp Biomech Sports 2005;49–56. 33. Kingma I, Aalbersberg S, van Dieen JH. Are hamstrings activated to counteract shear forces during isometric knee extension efforts in healthy subjects? J Electromyogr Kinesiol 2004;14:307–315. 34. O'Connor JJ. Can muscle co-contraction protect knee ligaments after injury or repair? J Bone Joint Surg Br 1993 Jan;75(1):41–48. 35. Pandy MG, Garner BA, Anderson FC. Optimal control of nonballistic muscular movements: a constraint-based performance criterion for rising from a chair. J Biomech Eng 1995 Feb;117(1):15–26. 36. Bendjaballah MZ, Shirazi-Adl A, Zukor DJ. Finite element analysis of human knee joint in varus-valgus. Clin Biomech 1997;12:139–148. 37. Matsumoto H, Suda Y, Otani T, et al. Roles of the anterior cruciate ligament and medial collateral ligament in preventing valgus instability. J Orthop Sci 2001;6:28–32. 38. Mazzocca AD, Nissen CW, Geary M, et al. Valgus medial collateral ligament rupture causes concomitant loading and damage of the anterior cruciate ligament. J Knee Surg 2003;16:148–151. 39. Fayad LM, Parellada JA, Parker L, Schweitzer ME. MR imaging of anterior cruciate ligament tears: is there a gender gap? Skeletal Radiol 2003;32:639–646.

Suggested Readings Boden BP, Dean GS, Feagin JA, et al. Mechanisms of anterior cruciate ligament injury. Ortho 2000;23:573–578. Caraffa A, Cerulli G, Projetti M, et al. Prevention of anterior cruciate ligament injuries in soccer. A prospective controlled study of proprioceptive training. Knee Surg Sports Traumatol Arthrosc 1996;4:19–21. Chappell JD, Herman DC, Knight BS, et al. Effect of fatigue on knee kinetics and kinematics in stop-jump tasks. Am J Sports Med 2005;33:1022–1029.

Mechanisms of Noncontact Anterior Cruciate Ligament Injuries Kanamori A, Woo SLY, Ma CB, et al. The forces in the anterior cruciate ligament and knee kinematics during a simulated pivot shift test: a human cadaveric study using robotic technology. J Arthroscop Relat Surg 2000;16:633–639. Li G, Rudy TW, Sakane M, et al. The importance of quadriceps and hamstring muscle loading on knee kinematics and in-situ forces in ACL. J Biomech 1999;32:395–400. Myklebust G, Engebretsen L, Braekken IH, et al. Prevention of anterior cruciate ligament injuries in female team handball players: a prospective intervention study over three seasons. Clin J Sports Med 2003; 13:71–78.

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Olsen O-E, Myklebust G, Engebretsen L, et al. Injury mechanisms for anterior cruciate ligament injuries in team handball. Am J Sports Med 2004;32:1002–1012. Petersen W, Braun C, Bock W, et al. A controlled prospective case control study of a prevention training program in female team handball players: the German experience. Arch Orthop Trauma Surg 2005;125:614–621. Soderman K, Werner S, Pietila T, et al. Balance board training: prevention of traumatic injuries of the lower extremities in female soccer players? A prospective randomized intervention study. Knee Surg Sports Traumatol Arthrosc 2000;8:356–363.

17

3

CHAPTER

Letha Y. Griffin James Kercher

Risk and Gender Factors for Noncontact Anterior Cruciate Ligament Injury INTRODUCTION In the past decade, there has been an increased emphasis on injury prevention in sports. However, a significant difficulty with designing prevention programs for anterior cruciate ligament (ACL) injury is our incomplete understanding of risk factors and mechanism of injury. Two different schemes exist for classifying risk factors. Risk factors can be divided into intrinsic factors, meaning those unique to the individual such as anatomy, muscle strength, and balance, and extrinsic factors, which are external influences on the body including such factors as shoe-surface interactions, braces, and weather conditions. Risk factors can also be categorized as environmental, anatomical, hormonal, neuromuscular, and genetic. The latter classification scheme will be the basis for this discussion.

ENVIRONMENTAL RISK FACTORS Many environmental risk factors specific to ACL injury have been studied, including weather and playing conditions, shoe-surface interaction, footwear, and bracing. These variables are important because they represent potentially avoidable risk factors. The foot plant, the shoe, the surface, and the shoe-surface interaction are critical factors in noncontact ACL injuries. Basic physics describes static and kinetic frictional forces between two bodies. Energy is dissipated once the static frictional force is overcome, allowing movement. This 18

is termed sliding, which causes a shift from static to kinetic frictional force that is more readily overcome. It is logical to assume that during foot plant, characteristics that increase static frictional force between the foot and ground will create higher-energy forces in the lower extremity. Certain studies have examined surface conditions relating to ACL injuries. Olsen et al1 and Torg et al2 both studied team handball and found an increased risk of ACL injury while playing on synthetic floors versus traditional parquet floors. Both believed that the increased friction of synthetic flooring was the cause. Orchard et al,3 Heidt et al,4 and Scranton et al5 all reported higher rainfall and cooler temperatures were related to decreased ACL injuries and theorized that dry, hot weather conditions promote increased frictional forces on the playing field, thus in turn resulting in increased injury rates. Lambson et al6 in a 3-year prospective study looked at footwear to evaluate torsional resistance of modern football cleats. They compared four styles of football shoes and found that the edge design, a design having longer irregular cleats at the periphery and many smaller cleats interiorly, was associated with higher ACL injury rates.

Bracing Pros and Cons Prophylactic and functional (postreconstructive) knee bracing has long been a controversial subject. Over the past 20 years, attitudes have fluctuated regarding the effectiveness of braces in preventing knee injury in the uninjured athlete,

Risk and Gender Factors for Noncontact Anterior Cruciate Ligament Injury the ACL deficient athlete, and the ACL reconstructed athlete. A study by Decoster and Vailas7 on brace prescriptions patterns noted that there has been a decreasing tendency for orthopaedic surgeons to prescribe ACL braces. The authors also noted that a primary factor influencing brace prescription by orthopaedists was the activity level of the patient.7 Early studies on prophylactic brace wear by Teitz et al8 and Rovere et al9 indicated no benefit to brace wear. These authors cited increased rates of knee injury in some athletes using prophylactic knee braces. In contrast, two other studies—the West Point study by Sitler et al10 involving 1396 cadets at the U.S. Military Academy who played intramural tackle football and the Big Ten Conference study by Albright et al11 involving 987 NCAA football players— concluded that prophylactic knee braces were effective in reducing injury. Since these studies, there has been a paucity of data to support prophylactic bracing for ACL injury protection, but it is believed that braces may provide some advantage to reducing medial collateral ligament (MCL) injury.12,13 Braces are commonly prescribed following ACL injury or reconstruction; however, little evidence supports their physiological or biomechanical efficacy. In a prospective randomized clinical trial of functional bracing for ACL deficient athletes, Swirtun et al14 found that subjectively, patients had initial sense of increased stability, but these investigators were unable to find objective benefits. In contrast, Kocher et al studied the use of braces to prevent reinjury in 180 ACL deficient alpine skiers and found reinjury occurred in 2% of the braced skiers compared with 13% of the unbraced “control” skiers.15 Risberg et al investigated the effect of knee bracing after ACL reconstruction in a prospective clinical trial of 60 patients randomized postoperatively (30 braced and 30 without brace) with 2 years of follow-up.16 They found no evidence that bracing affected knee joint laxity, range of motion, muscle strength, functional knee tests, patient satisfaction, or pain in braced athletes compared with athletes who did not use a brace following ACL reconstruction. Furthermore, they found prolonged bracing, which they defined as brace wear 1 to 2 years postoperatively, produced decreases in quadriceps muscle strength. McDevitt et al in a prospective, randomized multicenter study of 100 subjects likewise found no significant differences between braced and nonbraced subjects following ACL reconstruction.17 It has been theorized that damage to the ACL can disrupt mechanoreceptors in the knee leading to decreased proprioception.18 Birmingham et al19 has suggested that brace wear may help to correct this deficit somewhat, but benefits do not carry over to more demanding tasks. To examine knee proprioception, researchers have studied the threshold for detection of passive knee motion and found that brace application to the ACL deficient limb does not improve the threshold to detect passive range of motion.20,21

3

Although the preponderance of evidence would suggest that braces are ineffective in protecting the ACL deficient or reconstructed athletic knee, many patients still wish for a brace because they subjectively report that braces increase their confidence during sports participation.

ANATOMICAL RISK FACTORS Recognition of disparities in noncontact ACL injury rates between men and women has led to much debate on the association of gender-specific anatomical differences as potential injury risk factors. Proposed anatomical risk factors include increased quadriceps femoris angle (Q angle), ligamentous laxity in apparent knee valgus, femoral notch size, ACL geometry, subtalar joint pronation, and body mass index (BMI).

Association Between Q Angle and Injury Risk The Q angle, which typically ranges from 12 to 15 degrees, is formed by the intersection of two lines, one from the anterior superior iliac spine to the midpoint of the patella and another from the tibial tubercle to the same reference point on the patella. It has been proposed that an increased Q angle may be associated with an increased risk for knee injury because excessive lateral forces could negatively influence the knee's mechanical alignment.22,23 Females have been reported to have larger Q angles than their male counterparts24,25; however, in a trigonometric evaluation, Grelsamer et al reported a mean difference of only 2.3 degrees between the Q angles of men and women and furthermore found that men and women of equal height demonstrated similar Q angles.26 Shambaugh et al25 studied the relationship between lower extremity alignment and injury rates in recreational basketball players and found larger Q angles in athletes who sustained knee injures. In contrast, other authors have not been able to relate injury to Q angle.22,27,28 Guerra et al29 reported that quadriceps contraction alters Q angle measurements, thus making it difficult to establish a direct link between static Q angle measurements and injury.

Notch Width as a Risk Factor Structural characteristics of the distal femur and femoral intercondylar notch as well as ACL geometry and the ACL relationship to the intercondylar notch have been implicated as anthropometric factors associated with ACL injury rate disparity between males and females. It has been postulated that a smaller notch, termed notch stenosis, may cause impingement to the ACL and put it at increased risk 19

Anterior Cruciate Ligament Injury of injury, or possibly a smaller notch may imply a smaller ACL leading to decreased load to failure. Although these factors have been heavily studied using plain radiography,30–38 computed tomography (CT),39,40 magnetic resonance imaging (MRI),41,42 and cadaveric43-45 and in vitro37 analysis, a lack of consistent measurement techniques and findings has made it difficult to interpret results. Therefore there is still no consensus relating morphology of the intercondylar notch to ACL injury rates. A chronological summary of the data is listed in Table 3-1.

HORMONAL RISK FACTORS The increased incidence of ACL injury in women compared with men has raised interest regarding the influence of sex hormones on injury occurrence. Fig. 3-1 describes the menstrual cycle. A normal cycle is typically 28 to 30 days. The follicular phase (i.e., the stage of the follicle development) begins with menstruation and ends with ovulation. The latter lasts approximately 3 to 5 days and, if pregnancy does not occur, is followed by the luteal phase, which begins with the involution of the follicle and formation of the corpus luteum. Estradiol secretion is biphasic, peaking in both the follicular and luteal stages. Progesterone is produced by the corpus luteum and therefore occurs in the luteal phase only.

Monthly Distribution of Anterior Cruciate Ligament Injuries Initial surveys of injury occurrence throughout the monthly menstrual cycle revealed that injuries were not equally distributed throughout the cycle but instead were clustered either around menstruation or the ovulation period of the cycle.46–48 However, the reliability of these early data was questioned because subjects were not frequently controlled for the use of birth control pills and hormonal assays were not done

to verify cycle times; instead, athletes recalled or reported their menstrual history. Repeated studies using radioimmunoassays on serum, urine, or saliva verified the non–chance distribution of ACL injuries throughout the menstrual cycle.48–51

Sex Hormones and Laxity If sex hormone levels do influence injury rates, how this occurs is not clear. Multiple studies in the past decade have focused on the influence of sex hormones on knee laxity, and some investigators have even correlated female sex hormone levels and laxity measures with menstrual cycle phase. In 1999, Wojtys and Huston52 reported on a seriescontrolled study of 12 females and 12 males, in which they found a decrease in knee laxity on day 12 of the monthly menstrual cycle in women versus no monthly variation in knee laxity in men. In the following year, however, Belanger et al53reported no significant difference in anterior knee laxity throughout the monthly cycle in 18 Brown University athletes studied over 10 weeks. Similarly, Karageanes et al54 reported no significant changes in ACL laxity from the follicular to luteal phases. This research group measured laxity before workouts in 26 athletes, comparing these data to self-charted menstrual cycles. Van Lunen et al,55 using a within-subjects linear model, reported on 12 females tested for knee laxity at the onset of menses, near ovulation, and on day 23 with hormonal assays performed on blood drawn on those same days. They found no association between follicular, ovulatory, or luteal phase hormone concentrations and ACL laxity measures. This is in contrast to an earlier study by Heitz et al,56 who not only compared laxity measures taken on days 1, 10, 11, 12, 13, 20, 21, 22, and 23 of a self-reported menstrual cycle but also compared these data with serum estradiol and progesterone levels as measured by immunoassays in seven active females who reported normal 28- to 30-day menstrual cycles. These investigators found a significant difference in anterior knee laxity when comparing laxity

Proliferative phase (uterus) Follicular phase (ovary)

LH

Menstrual phase

Progestational phase (uterus) Luteal phase (ovary)

te es

ro

ne

og

Pr FSH Estrogen

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 1 2 Ovulation Menses Menses FIG. 3-1 A normal menstrual cycle. FSH, Follicle stimulating hormone; LH, luteinizing hormone.

20

Risk and Gender Factors for Noncontact Anterior Cruciate Ligament Injury

3

TABLE 3-1 Studies Evaluating Notch Size as an Anterior Cruciate Ligament (ACL) Injury Risk Factor Year Author

Study

Design

Conclusion

Comments

1987 Anderson

Analysis of the intercondylar

Retrospective study. Compared

Significant association between

Notchplasty for

notch by computed

bilateral ACL tears, unilateral tears,

anterior outlet stenosis and

those with

tomography

and normal knees in males and

unilateral and bilateral ACL tears.

documented

females using computed

No gender differences found.

stenosis

et al39

tomography (CT) scan. 1987 Houseworth et al40

The intercondylar notch in acute Retrospective study using computer Narrowed posterior arch of the

Positive

tears of the anterior cruciate

graphic analysis of notch-view

notch may predispose a knee to

association

ligament

radiographs in 50 patients with an

ACL tear.

between notch

acute ACL injury and 50 normal

and injury but no

knees.

comment on gender

112

1988 Souryal et al

Bilaterality in ACL injuries:

Retrospective analysis of 1120

associated intercondylar notch

patients with ACL ruptures. Devised bilateral group compared with

association

stenosis

notch width index (NWI) to

between notch

NWI was significantly less for unilateral and normal knees.

Positive

compare notch widths on

and injury but no

radiographs.

comment on gender

1993 Souryal et al38

Intercondylar notch size in ACL

Prospective blind study of 902 high Athletes with stenotic notch have

Females had

injuries in athletes

school athletes. ACL injuries were

greater risk for noncontact ACL

significantly

recorded and correlated with NWI.

injury. Limit of “critical stenosis”

smaller NWI

was NWI of 23/day

Cold machine

300

Postoperative brace

300

Functional brace Custom

1500

Shelf

800

Physical therapy

1000–3000

Femoral block

80

widely used devices, generally cost between $200 and $300 each. The cost differential between metal and bioabsorbable screws has largely disappeared, and most sales today are of the bioabsorbable devices. The former practice of using metal devices as a cost-saving measure is thus generally no longer productive. The tibial post screw stands alone as the least expensive tibial or femoral device, with a cost of less than $100. Some devices are priced as high as $500. In general there is little relationship between the sophistication of the device and its cost, and pricing by the companies would appear to be driven primarily by what the market will bear. Overall, combined tibial and femoral fixation device cost per case will generally be in the range of $400 to $500.

As is seen from the previous remarks and Table 9-1, disposables, tray rental, and fixation devices will produce an aggregate cost of $1200 per case; the cost is lower for the institution that owns its own ACL guide system. The addition of an allograft will increase the average cost to roughly $3200 per case. Thus, it can be seen that ACLR without allograft falls below total payer payments in virtually all cases, allowing the institution to retain some payment to cover its fixed costs. The addition of an allograft will not be problematic, provided it is separately reimbursed. Thus, from a microeconomic perspective, payer reimbursement of allografts becomes the key factor in preserving solvency.

Postoperative Costs Reimbursement is variable for some of the items in this section, as described here. If the surgeon wishes to use them, it is therefore important to check individual patient benefits to ensure that patients are not unexpectedly billed for items that they thought would be paid by their insurance provider.

Femoral Blocks In the Chicago area, femoral blocks are reimbursed at roughly $60 to $80 per block. They are reimbursed either using a specific Current Procedural Terminology (CPT) code or, more often, as an additional 15 minutes or so of anesthesia time. They have been shown to be highly cost effective by permitting reliable, same-day discharge.4–7 Although same-day discharge is routinely accomplished by most orthopaedic surgeons without the block, the block increases the percentage to nearly 100%, with greatly increased patient comfort. Pain is eliminated as a discharge obstacle, and nausea is also reduced as a discharge obstacle because there is no postoperative narcotic nausea exacerbation. Furthermore, femoral blocks clearly reduce short-term narcotic use after discharge, thus decreasing the incidence of nausea, constipation, and other opioid side effects at home, which can be significant in some patients. The small cost of the block is greatly outweighed by the overall reduced facility costs in allowing patients to leave the hospital expeditiously. The morbidity of these blocks has been negligible. 81

Anterior Cruciate Ligament Reconstruction

Cold Machines Motorized ice-flow machines cost about $300. They are beloved by patients for their pain-relieving properties. The literature, including a meta-analysis, shows their efficacy after ACLR8–10 and total knee arthroplasty.11 However, despite this favorable literature, third-party payers have increasingly refused to pay for motorized ice-flow machines in recent years. In the absence of insurance reimbursement, most patients are not willing to pay out of pocket for them.

Continuous Passive Motion Continuous passive motion (CPM) is somewhat less commonly used and more difficult to obtain reimbursement for than in prior years. Although early range of motion (ROM) may be improved, studies have failed to show significant benefit regarding ultimate ROM or postsurgical pain in ACLR.12–14 This parallels studies showing little or no long-term benefit after total knee arthroplasty.15–17 This literature has somewhat dampened third-party payer enthusiasm for these devices. The daily cost ranges upward from the Medicare rate of $23.

Postoperative Knee Braces Postoperative knee braces have a definite use in some rehabilitation protocols in regaining knee extension. They also provide protection in the postoperative period. Some surgeons do not use them. They are universally paid by payers as a separate cost item.

Functional Knee Braces So-called derotation braces were formerly routinely used when patients returned to pivoting activities. However, today they are used by far fewer surgeons than in past years. In the presence of a stable knee, there is no evidence that they are of significant benefit. In addition, the costs can be substantial, especially for custom braces. Many payers will reimburse the approximate $800 cost of “off the shelf” braces but not the higher $1500 price tag of custom braces.

but some do not. The number of available visits should be known in advance so that the surgeon does not use them all before the rehabilitation is completed. Many, but not all, plans will allow expanded benefits in cases of special need after appropriate appeal.

Future Added Costs Navigation Computerized navigation systems have been introduced18,19 but are not currently in widespread use. Their advantage is said to be greater tunnel placement accuracy. It is not clear whether their use will ever be widespread, but if so, they will add both direct cost and increased operative time cost to ACLR. The current cost of bringing in a system for a case is about $450. There is insufficient literature to evaluate relative outcomes with and without navigation. Some believe that the less-expensive option of simple intraoperative radiographs without computerized navigation can also be efficacious.

Double-Bundle Anterior Cruciate Ligament Reconstruction Double-bundle ACLR is more time consuming than singlebundle cases and thus increases surgical times. It also generally doubles implant costs because two femoral and two tibial implants are needed in most cases—an approximate average increase of $450 per case for fixation implants alone. Early clinical results have been good,20,21 but it is too soon to know whether the benefits are sufficient to justify the increased time, difficulty, and cost. Because many plans do not reimburse invoices at such a low level, the extra implant costs may ultimately be subtracted from the often-thin profit margin of these cases.

Tissue Engineering The use of growth factors and delivery vehicles for them is imminent.22,23 This will inevitably add significant cost to ACLR.

Physical Therapy Adequate physical therapy is necessary to restore motion, strength, and function. Although the costs vary by orders of magnitude among various regimens, there is little evidence regarding relative efficacies. Primarily home-based regimens are clearly more economical, but it is not clear that they are equally effective with clinic-based regimens. Also, the quantity of therapy needed varies somewhat by the demands of the patient, with high-performance competitive athletes generally needing more than others. Individual visit charges are also quite variable. The approximate cost range can vary from about $1000 to $3000 and much more in some cases. Most plans include physical therapy benefits, 82

CONCLUSIONS 1 Allograft usage is currently the largest and most important cost factor in ACLR. Macroeconomically, allograft use can potentially add almost $200 million to U.S. annual ACLR expenditures. Microeconomically, it is imperative that contracting provides for separate reimbursement above the basic cost of the procedure to avoid net loss to the institution. 2 Femoral nerve blocks are a cost-effective means to avoid the adverse economic effects of patient admission and improve postoperative pain control.

The Economics of Anterior Cruciate Ligament Reconstruction 3 CPM machines, cold machines, and functional knee braces are no longer universally reimbursed. Physical therapy is almost always covered but at variable levels. Patient benefits should be determined prior to prescription. 4 Tissue engineering, navigation, and double-bundle techniques will increase ACLR cost if they come into widespread use. Outcome studies will be necessary to determine whether benefits justify costs. 5 Surgeon choice is the most important factor in determining macroeconomic societal expense and microeconomic institutional solvency for ACLR. It is important to weigh patient outcomes against costs.

References 1. Curran AC, Park AE, Bach BR Jr, et al. Outpatient anterior cruciate ligament reconstruction: an analysis of changes and perioperative complications. Am J Knee Surg 2001;14:145–151. 2. Novak PJ, Bach BR Jr, Bush-Joseph CA, et al. Cost containment: a change comparison of anterior cruciate ligament reconstruction. Arthroscopy 1996;12:160–164. 3. Cole DW, Ginn TA, Chen GJ, et al. Cost comparison of anterior cruciate ligament reconstruction: autograft versus allograft. Arthroscopy 2005;21:786–790. 4. Dauri M, Polzoni M, Fabbi E, et al. Comparison of epidural continuous femoral block and intraarticular analgesia after anterior cruciate ligament reconstruction. Acta Anaesthesiol Scand 2003;47:20–25. 5. Williams BA, Kentor ML, Vogt MT, et al. Economics of nerve block pain management after anterior cruciate ligament reconstruction: potential hospital cost savings via associated postanesthesia care unit bypass and same-day discharge. Anesthesiology 2004;100:697–706. 6. Edkin BS, Spindler KP, Flanagan JF. Femoral nerve block as an alternative to parenteral narcotics for pain control after anterior cruciate ligament reconstruction. Arthroscopy 1995;11:404–409. 7. Williams BA, DeRiso BM, Figallo CM, et al. Benchmarking the perioperative process: III. Effects of regional anesthesia clinical pathway techniques on process efficiency and recovery profiles in ambulatory orthopedic surgery. J Clin Anesth 1998;10:570–578. 8. Raynor MC, Pietrobon R, Guiller U, et al. Cryotherapy after ACL reconstruction: a meta analysis. J Knee Surg 2005;18:123–129.

9

9. Barber FA. A comparison of crushed ice and continuous flow cold therapy. Am J Knee Surg 2000;13:97–101. 10. Barber FA, McGuire DA, Click S. Continuous-flow cold therapy for outpatient anterior cruciate ligament reconstruction. Arthroscopy 1998;14:130–135. 11. Morsi E. Continuous-flow cold therapy after total knee arthroplasty. J Arthroscopy 2002;17:718–722. 12. Gaspar L, Farkas C, Szepesi K, et al. Therapeutic value of continuous passive motion after anterior cruciate replacement. Acta Chir Hung 1997;36:104–105. 13. McCarthy MR, Yates CK, Anderson MA, et al. The effects of immediate continuous passive motion on pain during the inflammatory phase of soft tissue healing following anterior cruciate ligament reconstruction. J Orthop Sports Phys Ther 1993;17:96–101. 14. Richmond JC, Gladstone J, MacGillivray J. Continuous passive motion after arthroscopy assisted anterior cruciate ligament reconstruction: comparison of short- versus long-term use. Arthroscopy 1991;7:39–44. 15. Leach W, Reid J, Murphy F. Continuous passive motion following total knee replacement: a prospective randomized trial with follow-up to 1 year. Knee Surg Sports Traumatol Arthrosc 2006;14:922–926. 16. Denis M, Moffet H, Caron F, et al. Effectiveness of continuous passive motion and conventional phsycial therapy after total knee arthroplasty: a randomized clinical trial. Phys Ther 2006;86:174–185. 17. Lau SK, Chin KY. Use of continuous passive motion after total knee arthroplasty. J Arthroplasty 2001;16:336–339. 18. Plaweski S, Cazal J, Rosell P, et al. Anterior cruciate ligament reconstruction using navigation: a comparative study on 60 patients. Am J Sports Med 2006;34:542–552. 19. Hiraoka H, Kuribayashi S, Fukuda A, et al. Endoscopic anterior cruciate ligament reconstruction using a computer-assisted fluoroscopic navigation system. J Orthop Sci 2006;11:159–166. 20. Muneta T, Koga H, Morito T. A retrospective study of the midterm outcome of two-bundle anterior cruciate ligament reconstruction using quadrupled semitendinosus tendon in comparison with one-bundle reconstruction. Arthroscopy 2006;22:252–258. 21. Yasuda K, Kondo E, Ichiyama H, et al. Clinical evaluation of anatomic double-bundle anterior cruciate ligament reconstruction procedure using hamstring tendon grafts: comparisons among three different procedures. Arthroscopy 2006;22:240–251. 22. Ju YJ, Tohyama H, Kondo E, et al. Effects of local administration of vascular endothelial growth factor on properties of the in situ frozen-thawed anterior cruciate ligament in rabbits. Am J Sports Med 2006;34:84–91. 23. Yamazaki S, Yasuda K, Tomita F, et al. The effect of transforming growth factor-beta1 on intraosseous healing of flexor tendon autograft replacement of the anterior cruciate ligament in dogs. Arthroscopy 2005;21:1034–1041.

83

10 CHAPTER

Chadwick C. Prodromos Brian T. Joyce

PART A GRAFT MECHANICAL PROPERTIES

The Relative Strengths of Anterior Cruciate Ligament Autografts and Allografts INTRODUCTION Graft strength is only one of the factors influencing anterior cruciate ligament (ACL) graft choice. However, it has a direct bearing on ultimate stability, which is the goal of ACL. The relative strengths of potential ACL grafts are often not clearly appreciated. It is the purpose of this chapter to present the available data on the relative strengths of tendons that can be used as ACL reconstructive grafts.

METHODS Table 10–1 summarizes the data that we were able to find in the literature on graft strengths. Load to failure (LTF) is the parameter compared in each case. This data was found from computerized literature searches targeting ACL reconstruction and each of the specific grafts in clinical use. Although some tissue banks have performed their own studies on graft strengths, we have purposely excluded such proprietary data and relied only on data published in the peer-reviewed literature to avoid bias.

COMPARISON OF GRAFT STRENGTHS There is significant variability in LTF results among different studies for the same graft (see Table 10–1). This is likely related to differences in testing methodologies. Thus, it is necessary to look at the totality of the data to get an overall idea of relative graft strengths. Some of the 84

authors have what appears to be outlier LTFs, but the relative strengths between grafts within their study generally reflect the bulk of the literature. The two main examples here are the data of Brahmabhatt21 and Harris, with low LTFs for all grafts tested relative to other studies. When comparing grafts it is important also to notice the configuration of the tested grafts; in other words, whether it is a single, double, or quadruple graft, and in the case of bone–patellar tendon–bone (BPTB), whether it is a 10-mm or 15-mm graft. The data in Table 10–1 also show that braiding of grafts has been shown to weaken rather than strengthen grafts and is not clinically indicated.

EFFECT OF LIGAMENTIZATION Chapter 55 describes the effects of ligamentization on graft strength. Although there is some disagreement, it appears that grafts retain only about half their initial strength at long-term follow-up. Thus, grafts that are significantly stronger than the native ACL at time zero may indeed be necessary to produce ultimate strengths that are as strong as the ACL initially was. Indeed, some studies report a lower re-rupture rate for reconstructed ACLs than for the contralateral normal ACL,1 perhaps due to greater graft strength.

ALLOGRAFT STRENGTHS Autograft strengths are relatively straightforward to measure. However, allograft strengths

The Relative Strengths of Anterior Cruciate Ligament Autografts and Allografts

10

TABLE 10–1 Load to Failure Data for Anterior Cruciate Ligament Grafts Author

Year

Graft

Average

SD

Author

Year

Graft

Average

Load to

Load to

Failure (N)

Failure (N)

Allografts

SD

Hamner22

1999

2ST/2Gr

3880.0

NR

Haut22

2002

Double anterior tibialis

4122.0

893.0

Noyes19

1984

2ST/2Gr

4108.0

NR

Pearsall27

2003

Double anterior tibialis

3412.0

NR

Hamner22

1999

2ST/2Gr

4090.0

295.0

24

2003

2ST/2Gr

3000.0

563.0

2003

2ST/2Gr

3404.2

922.0

2002

2ST/2Gr

2913.0

645.0

2003

2ST/2Gr—braided

1673.0

504.0

2003

2ST/2Gr—braided

2223.5

1056.0

Pearsall

27

Haut22 Pearsall

27

King30 King

30

2003

Double peroneus

2483.0

NR

Kim

2002

Double post tibialis

3594.0

1330.0

Millett23 22

2003

Double post tibialis

3391.0

NR

Haut

2004

Achilles

1470.0

511.9

Kim24

2004

Tibialis

1806.7

496.2

25

Millett

Bone–patellar tendon–bone (BPTB)

Semitendinosus (ST) Brahmabhatt21

1999

Double ST

1029.0

158.4

Noyes19

1984

15-mm BPTB

2734.0

298.0

Hamner22

1999

Double ST

2330.0

452.0

Noyes19

1984

15-mm BPTB

2900.0

260.0

King30

2004

Double ST

1640.7

236.5

Harris31

1997

10-mm BPTB

876.0

NR

Noyes19

1984

Single ST

1216.0

50.0

Brahmabhatt21

1999

10-mm BPTB

850.0

159.2

Hamner22

1999

Single ST

1060.0

227.0

King30

Gracilis (Gr)

2004

10-mm BPTB

863.9

417.4

19

1984

10-mm BPTB

1822.7

NR

Noyes19

Noyes

Brahmabhatt21 22

1999

Double Gr

648.7

112.4

1984

10-mm BPTB

1933.3

NR

20

Hamner

1999

Double Gr

1550.0

428.0

Cooper

1993

10-mm BPTB

2664.0

395.0

Noyes19

1984

Single Gr

838.0

30.0

Cooper20

1993

10-mm BPTB

3057.0

351.0

1999

Single Gr

837.0

138.0

Quadriceps 1999

Quadriceps/bone

991.0

282.0

1997

Quadriceps/bone

1075.0

NR

22

Hamner

Double ST/double Gr (2ST/2Gr) 21

Brahmabhatt

1999

2ST/2Gr

Brahmabhatt21 1677.0

NR

Harris

31

NR, Not reported.

are more complicated because of the varying effects of graft preparation and sterilization techniques on the graft. Thus, any study that measures allograft strength can only be considered accurate for an allograft prepared in a similar manner. The relevant parameters may include radiated versus not radiated, the amount of radiation, and whether or not a radioprotectant was used. Other processes shown to significantly affect tissue properties include the use of cryoprotectant2 and even simple freezing.3 This is further complicated by the fact that these parameters may affect allograft strength at longer-term follow-up by influencing revascularization and cellular repopulation in addition to their effects at time zero. Thus, time zero data may not be sufficient for comparison between autografts and allografts, particularly in light of evidence that late failure rates may

be higher for allografts than for autografts.4–7 The literature has also shown overall lower stability rates for allograft BPTB versus autograft BPTB,8–17 suggesting that ligamentization may weaken allografts more than autografts.18

QUADRICEPS TENDON GRAFT STRENGTH The only published data we could find was from Brahmabhatt and Harris. Their LTF for the quadriceps tendon (QT) graft is quite low. However, we believe the proper way to interpret these data is by comparing them with their BPTB data, which are also much lower than other studies, probably due to testing methodology. The important point is that the QT LTF values in both of these studies are each about 20% 85

Anterior Cruciate Ligament Reconstruction stronger than the LTF for 10-mm BPTB tested the same way. Therefore, it would appear that a QT graft is likely a little stronger than a 10-mm BPTB graft.

RELATIVE STRENGTH OF HAMSTRING AND BONE–PATELLAR TENDON–BONE GRAFTS The classic paper of Noyes et al19 first compared various tissues with the ACL from the same cadaveric specimen. Other works have followed a similar methodology. These studies are summarized in Table 10–1. It should be noted that the study by Noyes et al used a 15-mm BPTB graft, whereas in practice a roughly 10-mm graft is used. Extrapolating from their numbers, a 10-mm BPTB graft would be 110% as strong as the native ACL. A two-strand semitendinosus (ST) and two-strand gracilis (Gr) (2ST/2Gr) graft would be 238% as strong as the native ACL. A four-strand ST (4ST) would be 280% as strong as the ACL. The real values for these multistrand grafts are probably a little less than these extrapolations because it is unlikely that the entire tendon is as strong as these index values. Some more recent studies have produced very different absolute numbers, perhaps related to testing methodological differences.20–29 However, within studies the relative strengths of various grafts show general agreement.

OVERALL RELATIVE GRAFT STRENGTHS Overall, 4ST and 2ST/2Gr grafts would appear to be the strongest available grafts in common use. Two-strand tibialis grafts are nearly as strong, followed by 10-mm BPTB and peroneus grafts, which are roughly two-thirds as strong as four-strand hamstring grafts. It should be pointed out that 15-mm BPTB can be used as an allograft and will more closely approximate the strength of a four-strand hamstring graft. The only data of which we are aware on tendo Achilles grafts show a low LTF. From the high girth of the graft it is likely, however, that a full-thickness tendo Achilles graft has much greater strength. This supposition will require more testing for validation.

CONCLUSIONS 1 Four-strand hamstring autografts are the strongest available grafts, followed by tibialis, QT, and BPTB grafts, with insufficient data to evaluate tendo Achilles grafts. All have greater strength than the native ACL. 2 Graft strength is only one of many factors contributing to knee stability after ACL reconstruction. 86

3 Because grafts appear to retain only about half of their time zero strength at ultimate follow-up, grafts significantly stronger than the native ACL would seem to be desirable. 4 Allograft ligamentization has not been well studied. LTF studies between autografts and allografts may not be comparable if the ligamentization of allografts differs significantly from that of autografts.

References 1. Prodromos CC, Han YS, Keller BL, et al. Stability of hamstring anterior cruciate ligament reconstruction at two- to eight-year follow-up. Arthroscopy 2005;21:138–146. 2. Caborn D, Nyland J, Chang HC, et al. Tendon allograft cryoprotectant incubation and rehydration time alters mechanical stiffness properties. Presented at the 2006 meeting of the European Society of Sports Traumatology, Knee Surgery, and Arthroscopy, Innsbruck, Australia, May 2006. 3. Clavert P, Kempf JF, Bonnomet F, et al. Effects of freezing/thawing on the biomechanical properties of human tendons. Surg Radiol Anat 2001;23:259–262. 4. Prodromos CC, Fu F, Howell S, et al. Controversies in soft tissue anterior cruciate ligament reconstruction. Presented at the 2006 Symposium of the American Academy of Orthopaedic Surgeons. AAOS Symposium; Controversies in Soft Tissue ACL Reconstruction, Chicago, May, 2006. 5. Scheffler S, Unterhauser F, Keil J, et al. Comparison of tendon-to-bone healing after soft tissue autograft and allograft ACL reconstruction in a sheep model. Presented at the 2006 meeting of the European Society of Sports Traumatology, Knee Surgery, and Arthroscopy, Innsbruck, Australia, May, 2006. 6. Siegel MG. Personal communication. Meeting of the Arthroscopy Association of North America, Hollywood, Florida, May, 2006. 7. Risinger RJ, Bach BR, Jr. Late anterior cruciate ligament reconstruction failure by femoral bone plug dislodgement. J Knee Surg 2006;19:202–205. 8. Barrett G, Stokes D, White M. Anterior cruciate ligament reconstruction in patients older than 40 years: allograft versus autograft patellar tendon. Am J Sports Med 2005;33:1505–1512. 9. Gorschewsky O, Klakow A, Riechert K, et al. Clinical comparison of the Tutoplast allograft and autologous patellar tendon (bone–patellar tendon–bone) for the reconstruction of the anterior cruciate ligament: 2- and 6-year results. Am J Sports Med 2005;33:1202–1209. 10. Harner CD, Olson E, Irrgang JJ, et al. Allograft versus autograft anterior cruciate ligament reconstruction: 3- to 5-year outcome. Clin Orthop Rel Rsch 1996;324:134–144. 11. Kleipool AEB, Zijl JAC, Willems WJ. Arthroscopic anterior cruciate ligament reconstruction with bone-patellar tendon-bone allograft or autograft: a prospective study with an average follow up of 4 years. Knee Surg Sports Traumatol Arthrosc 1998;6:224–230. 12. Peterson RK, Shelton WR, Bomboy AL. Allograft versus autograft patellar tendon anterior cruciate ligament reconstruction: a 5-year follow-up. Arthroscopy 2001;17:9–13. 13. Shelton WR, Papendick L, Dukes AD. Autograft versus allograft anterior cruciate ligament reconstruction. Arthroscopy 1997;13:446–449. 14. Stringham DR, Pelmas CJ, Burks RT, et al. Comparison of anterior cruciate ligament reconstruction using patellar tendon autograft or allograft. Arthroscopy 1996;12:414–421. 15. Victor J, Bellemans J, Witvrouw E, et al. Graft selection in anterior cruciate ligament reconstruction—prospective analysis of patellar tendon autografts compared with allografts. Int Orthop 1997;21:93–97. 16. Zijl JAC, Kleipool AEB, Willems WJ. Comparison of tibial tunnel enlargement after anterior cruciate ligament reconstruction using patellar tendon autograft or allograft. Am J Sports Med 2000;28:547–551.

The Relative Strengths of Anterior Cruciate Ligament Autografts and Allografts 17. Chang SKY, Egami DK, Shaib MD, et al. Anterior cruciate ligament reconstruction: allograft versus autograft. Arthroscopy 2003;19:453–462. 18. Prodromos CC, Joyce BT, Shi KS. A meta-analysis of stability of autografts compared to allografts after anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc (In press). 19. Noyes FR, Butler DL, Grood ES, et al. Biomechanical analysis of human ligament grafts used in knee-ligament repairs and reconstructions. J Bone Joint Surg Am 1984;66A:344–352. 20. Brahmabhatt V, Smolinski R, McGlowan J, et al. Double-stranded hamstring tendons for anterior cruciate ligament reconstruction. Am J Knee Surg 1999;12:141–145. 21. Cooper DE, Deng XH, Burstein AL, et al. The strength of the central third patellar tendon graft. Am J Sports Med 1993;21:818–824. 22. Haut Donahue TL, Howell SM, Hull ML, et al. A biomechanical evaluation of anterior and posterior tibialis tendons as suitable single-loop anterior cruciate ligament grafts. Arthroscopy 2002;18:589–597. 23. Hamner DL, Brown CH Jr, Steiner ME, et al. Hamstring tendon grafts for reconstruction of the anterior cruciate ligament: biomechanical evaluation of the use of multiple strands and tensioning techniques. J Bone Joint Surg Am 1999;81A:549–557. 24. Kim DH, Wilson DR, Hecker AT, et al. Twisting and braiding reduces the tensile strength and stiffness of human hamstring tendon

25.

26. 27.

28.

29.

30.

31.

10

grafts used for anterior cruciate ligament reconstruction. Am J Sports Med 2003;31:861–867. Millett PJ, Miller BS, Close M, et al. Effects of braiding on tensile properties of four-strand human hamstring tendon grafts. Am J Sports Med 2003;31:714–717. Nicklin S, Waller C, Walker P, et al. In vitro structural properties of braided tendon grafts. Am J Sports Med 2000;28:790–793. Pearsall AW, Hollis JM, Russel GV, et al. A biomechanical comparison of three lower extremity tendons for ligamentous reconstruction about the knee. Arthroscopy 2003;19:1091–1096. Stapleton TR, Curd DT, Baker CL Jr. Initial biomechanical properties of anterior cruciate ligament reconstruction autografts. J South Orthop Assoc 1999;8:173–180. Tis JE, Klemme WR, Kirk KL, et al. Braided hamstring tendons for reconstruction of the anterior cruciate ligament. Am J Sports Med 2002;30:684–688. King W, Mangan D, Endean T, et al. Microbial sterilization and viral inactivation in soft tissue allografts using novel applications of high-dose gamma irradiation. Presented at the American Academy of Orthopaedic Surgeons, March 2004, San Francisco,CA. Harris NL, Smith DA, Lamoreaux L, Purnell M. Central quadriceps tendon for anterior cruciate ligament reconstruction. Part I: Morphometric and biomechanical evaluation. Am J Sports Med 1997;5:725–727.

87

11 CHAPTER

Don Johnson

Why Synthetic Grafts Failed HISTORY OF SYNTHETIC GRAFTS FOR ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION Synthetic grafts for anterior cruciate ligament (ACL) reconstruction had a brief period of popularity in the mid-1980s. At this time the routine operation was an open patellar tendon graft with 6 weeks of postoperative immobilization. The concept of implanting a sterile, off-the-shelf synthetic ligament with no postoperative immobilization was very appealing. There was no harvest site morbidity, and the rehabilitation was very quick. In a very short period, it was recognized that there was a higher rate of failure compared with autogenous grafts, an increased rate of late infection, considerable bone tunnel enlargement, and significant sterile effusions; in addition, the grafts were expensive. In a 2005 article reviewing the choices of graft for ACL reconstruction, West and Harner1 stated that there is no indication for synthetic ligaments.

TYPES OF SYNTHETIC GRAFTS During the 1980s, numerous synthetic grafts were developed. They were used either as augmentation or as a complete prosthetic replacement. One of the original grafts that was designed as an augmentation device was the Kennedy ligament augmentation device (LAD). When this graft was sutured to the autogenous graft and fixed to the bone at both ends, it 88

stressed shielded the autogenous graft and led to failure. Gore-Tex was a prosthetic graft, but it was placed in a nonanatomical position over the top of the femur. The theory was to avoid the bending forces at the entrance to a femoral tunnel. However, because this was a nonanatomical position, it eventually led to graft failure at the proximal tunnel (a second tunnel was drilled in the femur several inches above the joint capsule). The Styker Dacron graft was a complete replacement graft placed through anatomical tunnels in the femur and tibia. The ABC graft was a combination of polyester and carbon fiber, and it was also placed through bony tunnels. The Ligastic graft was another polyester graft that evolved to the LARS graft. This was placed through bony tunnels and could be used as augmentation or as a complete prosthetic replacement. The graft was anchored in the tunnels with metal interference screws. The Leeds-Keio was a coventure between Leeds University in England and Keio University in Japan. This was a polyester mesh graft designed to augment the autogenous graft. It was placed through bony tunnels and anchored outside the tunnel with staples. The Trevira ligament was polyester and resembled the LAD in design, but it was placed in a nonanatomical position.

CAUSES OF FAILURE OF SYNTHETIC GRAFTS The most common cause of failure of synthetic grafts was the fiber abrasion due to bending forces

Why Synthetic Grafts Failed over the edge of the bony tunnels (Fig. 11-1). In order to avoid this problem, the Gore-Tex graft was placed over the top of the femur. This nonanatomical position eventually led to graft failure. Carson et al2 have stated that approximately 50% of the failures of ACL reconstruction are due to technical error, and the anterior femoral tunnel placement is one of the most common errors. It is likely that many of the failures of synthetic grafts were due to the same causes. The literature has numerous articles reporting the unacceptable failure rate after synthetic ACL reconstruction. Kumar and Maffuli3 reported on the stress shielding caused by the use of the LAD. Riel4 reported numerous complications following the use of the LAD and concluded that there was no indication for its use. Muren et al5 published results that showed no advantage to augmenting the patellar tendon graft with the LAD device. Guidoin et al6 reviewed 69 failed synthetic fiber ligament grafts and found that they all failed by fiber abrasion of the textile fiber around the bony tunnel edge. Kock et al7 stated that the Trevira ligament failed due to fiber abrasion and the nonanatomical position of the graft. Wredmark and Engstrom8 reviewed the results of the Stryker Dacron graft and found an 80% failure rate. Engstrom et al9 also compared the Leeds-Keio with an autogenous patellar tendon graft and found the failure rate of the synthetic to be unacceptable. Andersen et al10 reported unsatisfactory results with the Dacron synthetic graft. Bowyer and Matthews11 reported an unacceptable failure rate with the Gore-Tex ligament graft. Indelicato et al12 reported on the sterile effusions that were foreign body reactions to the synthetic graft. Woods et al13 published the deteriorating results of the Gore-Tex graft with longer follow-up from 2 to 3 years. Barrett et al14 also reported on the high failure rate (47%) with the Dacron synthetic ligament. This ligament had been placed in a nonanatomical, over-the-top position. Paulos et al15 reported 13% fair and 42% poor results with the Gore-Tex graft. Looseness and failure of the graft occurred in 30% of the cases with this graft placed in the over-the-top position. The 2.7% infection rate was higher than that reported with autogenous grafts.

FIG. 11-1 The Gore-Tex ligament failure at the tunnel entrance.

11

OTHER PROBLEMS WITH SYNTHETIC GRAFTS The problem of synthetic grafts is not only that they failed, but that there were other significant issues such as biocompatibility. The carbon fiber grafts produced a black synovitis in the joint. The regional lymph nodes also became enlarged with the carbon fiber debris. The Gore-Tex ligament often produced a very severe sterile synovitis that resembled a septic arthritis (Fig. 11-2). This prompted many patients to undergo a repeat arthroscopy to irrigate the joint. Biopsy of the synovium showed a foreign body reaction. The Gore-Tex ligament would occasionally produce a ganglion-type reaction at the tibial tunnel that required excision (Fig. 11-3). The bony tunnels would often become extremely large, requiring removal of the graft and bony grafting of the tunnels (Fig. 11-4). The revision ACL reconstruction would be staged some months later, when the bony tunnels had healed.

THE FUTURE There is still considerable interest and investigation into some form of synthetic bioabsorbable scaffold to implant into the stump of the ACL after injury to the ligament.16 In fact, a type of scaffold that is augmented with growth factors holds the most promise for the future. This minimally invasive approach to ACL repair would be an improvement over the relatively barbaric procedure of harvesting of the hamstring tendons to reconstruct the ACL.

FIG. 11-2 The severe foreign body reaction to the Gore-Tex ligament.

89

Anterior Cruciate Ligament Reconstruction

FIG. 11-3 A large ganglion type of foreign body reaction at the tibial tunnel entrance.

References 1. West RV, Harner CD. Graft selection in anterior cruciate ligament reconstruction. J Am Acad Orthop Surg 2005;13:197–207. 2. Carson EW, Anisko EM, Restrepo C, et al. Revision anterior cruciate ligament reconstruction: etiology of failures and clinical results. J Knee Surg 2004;17:127–132. 3. Kumar K, Maffullli N. The ligament augmentation device: an historical perspective. Arthroscopy 1999;15:422–432. 4. Riel KA. [Augmented anterior cruciate ligament replacement with the Kennedy-LAD (ligament augmentation device)—long term outcome]. Zentralbl Chir 1998;123:1014–1018. 5. Muren O, Dahlstedt L, Dalen N. Reconstruction of acute anterior cruciate ligament injuries: a prospective, randomised study of 40 patients with 7-year follow-up. No advantage of synthetic augmentation compared to a traditional patellar tendon graft. Arch Orthop Trauma Surg 2003;123:144–147. 6. Guidoin MF, Marois Y, Bejui J, et al. Analysis of retrieved polymer fiber based replacements for the ACL. Biomaterials 2000;21:2461–2474. 7. Kock HJ, Sturmer KM, Letsch R, et al. Interface and biocompatibility of polyethylene terephthalate knee ligament prostheses. A histological and ultrastructural device retrieval analysis in failed synthetic implants used for surgical repair of anterior cruciate ligaments. Arch Orthop Trauma Surg 1994;114:1–7. 8. Wredmark T, Engstrom B. Five-year results of anterior cruciate ligament reconstruction with the Stryker Dacron high-strength ligament. Knee Surg Sports Traumatol Arthrosc 1993;1:71–75. 9. Engstrom B, Wredmark T, Westblad P. Patellar tendon or Leeds-Keio graft in the surgical treatment of anterior cruciate ligament ruptures. Intermediate results. Clin Orthop Relat Res 1993;6:190–197.

90

FIG. 11-4 The tunnel enlargement (arrows) after a Gore-Tex ligament implantation.

10. Andersen HN, Bruun C, Sondergard-Petersen PE. Reconstruction of chronic insufficient anterior cruciate ligament in the knee using a synthetic Dacron prosthesis. A prospective study of 57 cases. Am J Sports Med 1992;20:20–23. 11. Bowyer GW, Matthews SJ. Anterior cruciate ligament reconstruction using the Gore-Tex ligament. J R Army Med Corps 1991;137:69–75. 12. Indelicato PA, Pascale MS, Huegel MO. Early experience with the GORE-TEX polytetrafluoroethylene anterior cruciate ligament prosthesis. Am J Sports Med 1989;17:55–62. 13. Woods GA, Indelicato PA, Prevot TJ. The Gore-Tex anterior cruciate ligament prosthesis. Two versus three year results. Am J Sports Med 1991;19:48–55. 14. Barrett GR, Line LL Jr, Shelton WR, et al. The Dacron ligament prosthesis in anterior cruciate ligament reconstruction. A four-year review. Am J Sports Med 1993;21:367–373. 15. Paulos LE, Rosenberg TD, Grewe SR, et al. The GORE-TEX anterior cruciate ligament prosthesis. A long-term followup. Am J Sports Med 1992;20:246–252. 16. Bourke SL, Kohn J, Dunn MG. Preliminary development of a novel resorbable synthetic polymer fiber scaffold for anterior cruciate ligament reconstruction. Tissue Eng 2004;10:43–52.

PART B AUTOGRAFT HARVEST TECHNIQUES

Hamstring Harvest Technique for Anterior Cruciate Ligament Reconstruction ABSTRACT The use of the hamstring tendons for anterior cruciate ligament (ACL) reconstruction has gained in popularity over the past several years. For those unfamiliar with the harvest technique of the hamstring tendons, this is often the most difficult part of the procedure. Several important steps in the procedure are described to avoid the common complication of cutting the grafts short.

TECHNIQUE OF HAMSTRING GRAFT HARVEST The graft harvest can be the most difficult aspect of this operation. Videotapes of this technique by Fowler, Prodromos, and Fox are available from the AAOS library.1 The anatomy of the hamstrings has been described in the literature by Ferrari and Ferrari.2 The strength of the hamstrings after harvest of the tendons was initially reported by Lipscomb et al3 to be the same as the opposite side. Since then, weakness of knee flexion above 90 degrees of knee flexion has been reported.4 Based on these reports, one should be cautious in recom­ mending hamstring grafts for sprinters, who require full, active knee flexion strength. Yasuda et al5 have described the harvest site morbidity as minimal. Gobbi et al6 recommend preser­ vation of the gracilis to prevent postoperative knee flexion weakness. The regeneration of the

hamstring tendons after the harvest was described by Cross et al.7

12 CHAPTER

Don Johnson

SKIN INCISION The skin incision for hamstring harvest should be made with the knee flexed in the figure-four position (Fig. 12-1). An oblique, 3-cm skin incision is made 5 cm below the joint line over the proximal edge of the pes anserine. The inci­ sion should start 1 cm medial to the tibial tuber­ cle and then continue posteromedially. The oblique incision is preferable to the vertical inci­ sion for two reasons: It gives a greater exposure to the top of the pes anserine, and it also has less potential to injure the infrapatellar branch of the saphenous nerve. Plan to harvest the graft and drill the tibial tunnel through this incision. Incise the subcutaneous fat, and strip the fat off the pes anserine with a sponge.

EXPOSURE OF THE TENDON Identify the superior border of the pes by pal­ pating the superior edge with your finger. Lift up this superior border, and incise the fascia. Identify the bursa between the pes and the medial collateral ligament by placing the tip of the scissors in the space. With the scissors, continue the incision medially down the tibia, in an L-shaped fashion, removing the tendons distally. Use a Kocher to apply traction to this

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TENDON RELEASE Free the distal end of the tendon with the scissors. Make sure you get the full length distally. Grasp it with a Kocher, and pull it firmly into the incision. Many of the bands can be released with the traction and by blunt finger dissection. The main band that goes to the medial head of the gastrocne­ mius will usually have to be cut with the scissors (Fig. 12-3). Pull firmly on the tendon, and cut away from the tendon (to avoid cutting the tendon with the scissors) (Fig. 12-4). The tendon should not retract proximally if all the bands are cut. When the tendon is pulled distally, there is no dimpling posteriorly over the gastrocnemius.

STRIPPING OF THE TENDON FIG.12-1 The oblique anteromedial incision for hamstring harvest.

Advance the tendon stripper up over the tendon to free it from the muscle proximally (Fig. 12-5). The key to a successful

top corner. Turn the pes down to look on the underside for the most inferior tendon, the semitendinosus (Fig. 12-2). Lift the tendon up with the tip of the scissors, and grasp it with a Kocher. Lift up the gracilis, and grasp it in a similar fashion with a Kocher. Divide the conjoined tendon between the semitendinosus and the gracilis.

FIG. 12-3 The bands from the tendon to the gastrocnemius are identified and cut.

FIG. 12-2 The pes is turned down to visualize the tendons on the underside.

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FIG. 12-4 The scissors are used to cut the bands to the gastrocnemius.

Hamstring Harvest Technique for Anterior Cruciate Ligament Reconstruction

12

FIG. 12-7 The two tendons are looped over a suture. FIG. 12-5 The tendon stripper is pushed up the tendon to remove it proximally from the muscle.

harvest is to keep tension on the distal end. This will prevent the tendon from folding over and being cut off short (Fig. 12-6). Make sure that the tendon stripper is heading up the thigh in the same direction as the tendon. There is often resistance at the muscle tendon junction, and the stripper should be rotated to slip it up along the surface of the muscle. This gives extra length. The total length is usually 28 to 30 cm. Strip the gracilis tendon in a similar fashion.

PREPARATION OF THE GRAFT Preparation of the Four-Bundle Semitendinosus and Gracilis Graft Take the graft to the graft master on the back table. Lay out, measure, and cut the graft to 22 cm. Remove the muscle with the periosteal elevator. Loop the two tendons over a

FIG. 12-6 One small band may kink the tendon, and the stripper will cut the tendon off short.

#5 braided nonabsorbable suture to produce an 11-cm graft (Fig. 12-7). With this length, 2.5 cm is in the femur, 2.5 cm is intraarticular, and 5 cm is in the tibial tunnel. This ensures a small portion of the graft is at the cortex of the tibia for fixation with the screw. Whipstitch the individual ends of the tendons with a #2 nonabsorbable suture for a distance of 4 cm (Fig. 12-8). Make sure that each tendon has a suture in it. This allows you to tension each bundle of the composite graft. The completed four-bundle graft should be 11 cm in length. This four-bundle graft will be three times the strength of a single strand of semitendi­ nosus, assuming all bundles are equally tensioned.8 Incor­ porate the graft into the bone tunnel by Sharpey fibers.9 This will take about 10 to 12 weeks to heal. This graft will have at least 2.5 cm of graft in each tunnel. The depth of graft in the tunnel can be determined by the suture marks at each end.

Graft Sizing Measure the size of the composite graft to the nearest half centimeter (7.5 mm and 8 mm are the most common sizes) (Fig. 12-9). Drill the tunnels according to the size of the tendon.

FIG. 12-8 The tendon ends are whipstitched individually.

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Anterior Cruciate Ligament Reconstruction the tendons into the wound to avoid pushing the scissors proximally and injuring the saphenous nerve.

� After the bands have been divided and there is no dimpling of the skin when the tendon is tugged, you can proceed to use the stripper to remove 22 to 25 cm of tendon. FIG. 12-9 Sizing of the graft.

TIPS FOR HARVESTING THE HAMSTRING GRAFTS TO AVOID COMPLICATIONS � Make sure that the incision is in the correct position to easily access the tendons. The landmarks are found with the knee in the figure-four position. The incision should be oblique, running from 2 cm medial to the tibial tubercle and 5 cm below the joint line (3 fingerbreadths) and directly along the course of the tendons.

� After making the skin incision and stripping the fat off the fascia, palpate the tendons and incise the fascia on the superior surface.

� Use the tip of the Metz to fall into the pes bursa. This ensures that you are in the correct plane and will not dissect under the medial collateral ligament.

� Use the scissors or knife to remove the tendon attachment to the tibia. Turn this flap over to visualize the two tendons. Split the conjoined tendon distally.

� Now pull the tendon into the wound to show the bands that attach to the gastrocnemius. It is preferable to pull

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References 1. www.aaos.org. 2. Ferrari JD, Ferrari DA. The semitendinosus: anatomic considerations in tendon harvesting. Orthop Rev 1991;20:1085–1088. 3. Lipscomb AB, Johnston RK, Snyder RB, et al. Evaluation of hamstring strength following use of semitendinosus and gracilis tendons to reconstruct the anterior cruciate ligament. Am J Sports Med 1982;10:340–342. 4. Tashiro T, Kurosawa H, Kawakami A, et al. Influence of medial hamstring tendon harvest on knee flexor strength after anterior cruciate ligament reconstruction. A detailed evaluation with comparison of single- and double-tendon harvest. Am J Sports Med 2003;31:522–529. 5. Yasuda K, Tsujino J, Ohkoshi Y, et al. Graft site morbidity with autogenous semitendinosus and gracilis tendons. Am J Sports Med 1995;23:706–714. 6. Gobbi A, Domzalski M, Pascual J, et al. Hamstring anterior cruciate ligament reconstruction: is it necessary to sacrifice the gracilis? Arthros­ copy 2005;21:275–280. 7. Cross MJ, Roger G, Kujawa P, et al. Regeneration of the semitendino­ sus and gracilis tendons following their transection for repair of the anterior cruciate ligament. Am J Sports Med 1992;20:221–223. 8. Hamner DLB, Steiner CH Jr, Hecker ME, et al. Hamstring tendon grafts for reconstruction of the anterior cruciate ligament: biomechani­ cal evaluation of the use of multiple strands and tensioning techniques. J Bone Joint Surg Am 1999;81:549–557. 9. Weiler A, Hoffmann RF, Bail HJ, et al. Tendon healing in a bone tun­ nel. Part II: histologic analysis after biodegradable interference fit fixa­ tion in a model of anterior cruciate ligament reconstruction in sheep. Arthroscopy 2002;18:124–135.

Posterior Mini-Incision Hamstring Harvest Approach for Anterior Cruciate Ligament Reconstruction* OVERVIEW Hamstring (HS) use for anterior cruciate ligament reconstruction (ACLR) has increased greatly in the past 5 years as improved fixation techniques have allowed stability rates to meet or exceed those of bone–patellar tendon–bone (BPTB) grafts.1 It has been said that the harvest is the most difficult part of HS ACLR2 and may require a learning curve of roughly 50 procedures.3 The primary difficulty is that the intertendinous cross-connections of the semitendinosus (ST) and gracilis (Gr) must be sectioned before the tendon stripper is used to harvest the tendons. If they are not, the tendons can be cut too short to use, necessitating an unplanned switch to a different graft. These crossconnections, however, are significantly posterior to the traditional anterior harvest incision, requiring often-difficult retraction and dissection to reach. The primary benefit of the posterior approach is that it puts the incision in the area of the cross-connections, thus facilitating their visualization and sectioning. The second benefit of the technique is that it allows easier location and identification of the ST and Gr in the posterior incision, where they are separate from each other and easy to find. In the area of the traditional anterior approach, the tendons exist as a single insertional structure, which requires posterior dissection for positive *

The principles and technique described in this chapter are presented in greater detail in the DVD that accompanies this textbook.

identification of individual tendons. This is made more difficult by the close apposition of the superficial fascial sheath anteriorly, whereas posteriorly the fascia is separated from the tendons by fat. The anterior incision, when used in conjunction with the posterior mini-incision, is then used only for tibial tunnel drilling and tibial fixation. It can thus be made much smaller than in the traditional anterior technique, only about 1 inch in length. The author has used this technique continuously without problem for 15 years since devising it after 6 years of experience with the traditional anterior approach.

13 CHAPTER

Chadwick C. Prodromos

ANATOMY The accessory ST tendon is the primary structure leading to premature amputation of the ST tendon after tendon harvesting. This structure is not described in any standard anatomy texts. However, several papers have described it.4–6 It is present in about 70% of patients. Other crossconnections exist variably from the ST and Gr tendons. In some patients they are thin and will be easily cut with a tendon stripper. However, the accessory ST in particular can be almost as thick as the main trunk of the ST. Especially in these cases, the tendon stripper can easily sever the main trunk of the ST, rendering it too short to use. The variability of the anatomy is such that it is difficult to devise a consistent plan for freeing the tendon using the traditional approach, except to run a scissors along both sides of both tendons. 95

Anterior Cruciate Ligament Reconstruction Branches of the saphenous nerve, and indeed its main trunk, are very close by, and saphenous neurapraxia is very common after these dissections. The takeoff of the accessory ST was shown in our studies to be an average of 5 to 6 cm posterior to the tibial crest. Although orthopaedic surgeons rarely operate posteriorly and may be apprehensive about a posterior approach, the posterior approach does not subject neurovascular structures to significant risk. Our cadaver studies showed that the closest neurovascular structure was the popliteal artery, but in eight specimens it was always at least 2.9 cm away from the ST tendon. It was also shielded from the ST tendon by the semimembranosus muscle.

SURGICAL TECHNIQUE

to see posteromedially. The incision should be made directly over it in the popliteal fossa, shading slightly anteromedially (Fig. 13-1). If the ST cannot be felt, the incision can be put into the soft spot in the skin just medial to the midline. The location of this incision is not critical because the tendon can always be found by moving the highly mobile skin in this area. The incision should be made 3 cm in length initially but need only be 2 cm in length once experience is gained. It should be put within or parallel to a skin crease. After the dermis is incised with a #15 blade, the subcutaneous tissue is opened by spreading with Metzenbaum scissors.

Finding the Semitendinosus

The patient is positioned supine. We use a lateral post rather than a circumferential leg holder, but the latter can be used if the surgeon desires.

An index finger should probe the incision, fishing the tendon out bluntly. If it is not easily found in this manner, two Senne retractors can be used to open the incision, and the tendon can be found under direct visualization. Once the tendon is identified, a right-angle clamp is passed around it. A ¼-inch Penrose drain then captures it and is loosely clamped (Fig. 13-2).

Making the Posterior Skin Incision

Finding the Semitendinosus Insertion

The ST is the most prominent tendinous structure in the popliteal fossa and runs just medially to the midline. The affected lower extremity is externally rotated, and the knee is flexed about 30 degrees. The surgeon bends over the leg

Once the tendon is identified, the surgeon runs his or her index finger under it to its tibial insertion. This may necessitate opening the fascia posteriorly slightly with Metzenbaum scissors. At the insertion the surgeon can verify that he or

Patient Positioning

Sartorius Semitendinosus Semimembranosus Gracilis Mini-incision

Tibial nerve Popliteal vein Popliteal artery

FIG. 13-1 The semitendinosus (ST) and gracilis (Gr) tendons are shown posteriorly, where they are separate from each other and easy to identify.

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Posterior Mini-Incision Hamstring Harvest Approach for Anterior Cruciate Ligament Reconstruction

FIG. 13-2 The semitendinosus (ST) tendon is isolated in the posterior mini-incision.

13

FIG. 13-3 The semitendinosus (ST) is isolated in the anterior mini-incision.

she indeed has the ST and not the Gr, which is sometimes found first. The ST is the most distal tendinous insertion in the pes. If the Gr is found first, the surgeon can find the insertion of the ST adjacent to the insertion of the Gr. The surgeon can then pull his or her finger back to the posterior incision to find the ST there.

Making the Anterior Incision The skin is tented just anterior to the posteromedial tibial border by the index finger inserted in the posterior incision under the ST. The surgeon makes a 2-cm longitudinal incision here with a #15 blade. This area is then opened with Metz scissors, and the superficial fascia is incised carefully to avoid scoring the tendons.

FIG. 13-4 The gracilis (arrow) is isolated in the anterior mini-incision.

Identifying the Semitendinosus in the Anterior Incision

Harvesting the Semitendinosus and Sectioning the Accessory Semitendinosus

A right-angle clamp is inserted in the anterior incision and passed around the ST tendon to grasp a ¼-inch Penrose drain (Fig. 13-3). The surgeon's other index finger is still under the tendon and guides the clamp. The surgeon may insert the short end of an Army-Navy retractor and identify the tendon by direct visualization. A ¼-inch Penrose is then passed around the tendon and clamped with a right angle.

A small, closed corkscrew tendon stripper is passed around the ST near its common insertion with the Gr without disrupting it. It is gently but firmly passed proximally with a firm rotary, back-and-forth motion. Resistance will be felt when the stripper encounters the accessory ST (Fig. 13-5). At this point the stripper should be carefully advanced another 1 or 2 cm, taking care not to apply excessive force. Two Senne rakes are then placed in the posterior incision, and the mobile skin is moved anteriorly over the head and neck of the tendon stripper to expose them while maintaining firm pressure on the stripper. The surgeon uses a forceps and Metz scissors to dissect the filmy tissue off the stripper neck. Sitting directly on the neck of the tendon stripper will be the accessory ST, with the main trunk of the tendon extending outward from the corkscrew (Fig. 13-6). This accessory ST should be cut with either a Metz scissors or a #15 blade. The stripper will now slide freely

Identifying the Gracilis Using the ST as a guide, the Gr can be found either in the posterior or anterior incision (Fig. 13-4) either before or after the ST is stripped proximally. If the ST is 30 cm or longer, we do not harvest the Gr but rather use a four-strand ST graft.

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Anterior Cruciate Ligament Reconstruction

Sartorius Gracilis Semimembranosus sling Main semitendinosus

Incision Incision

Accessory semitendinosus

FIG. 13-5 The tendon stripper is shown as it is about to deliver the accessory semitendinosus crossconnection out of the posterior miniincision.

need only slide his or her index finger along the tendon with the tendon stripper via the posterior incision. The surgeon can guide it so that it does not get caught up on fascia but rather glides along the tendon. The surgeon can also effectively dilate the path the tendon stripper takes proximally, allowing it to pass further until the full length of the tendon is harvested.

Freeing the Tendon Distally

FIG. 13-6 The accessory semitendinosus (ST) sits on the neck of the tendon stripper outside of the posterior incision, where it can be easily sectioned under clear visualization.

toward the proximal. It should be pushed until the tendon is freed proximally while countertension is maintained with a ¼-inch Penrose or index finger near its insertion. Once freed, the ST is delivered out the anterior incision.

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With the two (or one) tendons delivered out the anterior incision, the periosteum is scored parallel and to the deep side of the tendon(s) (Fig. 13-7). An additional 2 cm of periosteum can then be harvested in line with the insertion, essentially prolonging it with tough tissue that also has the benefit of the growth factors found on its cambium layer for intratunnel fixation and ingrowth.

Graft Preparation The tendon(s) is given to the assistant at the back table for cleaning and measuring.

What if the Tendon Stripper Gets Caught in the Thigh?

Time of Harvest

This can happen at the semimembranosus sling or at the fanning-out of the ST. If firm resistance is met, the surgeon

The harvest can usually be accomplished in less than 10 minutes. However, occasionally the harvest will be a little

Posterior Mini-Incision Hamstring Harvest Approach for Anterior Cruciate Ligament Reconstruction

13

Problem 2: Tendon Identification When only an anterior incision is used, its location must be estimated from the tibial tubercle. When the fascia is lifted, it can be difficult to clearly identify which pes tendon is which or even where the tendon starts and the fascia ends—particularly in large patients—because the ST and Gr insert as a common tendon. As they course distally, they cease being separate structures at roughly the posteromedial tibial border. Definite verification involves posterior dissection to this point or beyond where the anatomy is clearer. This can be time consuming and also increases the risk of saphenous neurapraxia. FIG. 13-7 The harvested semitendinosus/gracilis (ST/Gr) tendon is seen with periosteum extending the common insertion onto the tibia.

more difficult. In these cases the surgeon should take time to find and free the tendons safely. The greatest virtue of this technique is that the bi-incisional access allows the surgeon to accomplish even the most difficult harvests safely. However, patience and more time are required for some harvests, and the surgeon should not be in a rush if the harvest is problematic. It is still possible to cut the tendon short if the surgeon attempts to force rather than finesse a difficult harvest.

HARVEST PROBLEMS WITH THE TRADITIONAL APPROACH AND SOLUTIONS USING THE COMBINED POSTERIOR/ANTERIOR MINI-INCISION APPROACH Problem 1: Premature Tendon Amputation The chief danger in the harvest is that the intertendinous cross-connections, which variably occur, will not be adequately sectioned prior to harvesting with the tendon stripper as described earlier, resulting in premature tendon amputation. These cross-connections can be difficult to visualize from the anterior approach.

Solution The posterior mini-incision facilitates identification of the intertendinous cross-connections by putting the incision where these structures exist—posteromedially. The tendon stripper delivers the cross-connections out of this incision, where they can be sectioned under direct vision, instead of in the depths of the anterior incision, where both they and neurovascular structures are difficult to see.

Solution The pes tendons exist as separate structures roughly 1.5 cm apart posteriorly. The ST can usually be easily palpated posteriorly, which is not the case anteriorly. A small posterior incision placed directly over the ST and slightly anteromedial to it allows ready identification of the ST. Running an index finger under this tendon precisely allows placement of the anterior incision over the tendon insertion by tenting the skin at this point.

Problem 3: Hang-Up of the Tendon Stripper in the Distal Thigh at the Fanning-Out of the Semitendinosus or Semimembranosus Sling Even if the cross-connections are cut, the tendon stripper can still cut the tendon short at this point. This point is too high up in the thigh to be reached from a traditional anterior approach.

Solution If marked resistance to the tendon stripper is met in the thigh, an index finger can be inserted up the thigh through the posterior incision to free it, after which the stripper will easily pass.

Problem 4: Saphenous Nerve Trauma and Numbness Numbness has been shown to occur in more than half of patients after ACL surgery.7,8 Most of the time it is not significantly bothersome to the patient. However, it is bothersome to occasional patients. In addition, there is evidence that stiffness and complex regional pain syndrome (formerly reflex sympathetic dystrophy) are more common with significant nerve trauma after knee surgery.

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Anterior Cruciate Ligament Reconstruction

Solution The posterior mini-incision diminishes saphenous nerve trauma in three ways. First, the posterior mini-incision is posterior to the saphenous nerve, where there is no danger of trauma to it or its branches. Second, the anterior incision is made much smaller because the posterior incision allows it to be precisely placed. This decreases the chances that a saphenous branch such as the infrapatellar branch will be cut. Third, because the tendon stripper delivers the crossconnections externally out of the posterior incision, there is no need to dissect and retract anteriorly. This diminishes trauma to the saphenous nerve and its branches from retraction and dissection. We have found that if only the short end of an Army-Navy is used for retraction, and if very little retraction is done, the incidence of numbness is much less than if longer retractors are used or vigorous retraction is performed.

Problem 5: Cosmesis Cosmesis is not generally a significant problem, but our studies have shown4 that cosmesis does matter to many patients, especially to females.

Solution The posterior incision is hidden and becomes essentially invisible. The anterior incision is much smaller, usually only 1 inch or smaller, and it is the only incision the patient sees. It also becomes very hard to detect by 1 year after surgery.

Problem 6: Harvest in Large Patients It has been suggested that allografts are a better choice than HS in large or obese patients because of the difficulty of the harvest.

Solution The presence of a posterior incision removes the difficulty in finding, identifying, and freeing the tendon. It is more difficult than in a slender person but can always be accomplished. The usually 1-inch incisions should be made a little larger, but no other technical modifications are necessary.

CLINICAL EXPERIENCE We have used this technique continuously and exclusively since 1991. Harvested ST tendons tend to vary between 24 and 34 cm in length. Depending on ST length, we will either perform a 4ST or 2ST/2Gr graft. Roughly 85% of our grafts are 2ST/2Gr. We have never had tendons cut

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too short to produce a four-strand graft. We have had no complications referable to this approach, neurovascular or otherwise. In addition to essentially eliminating the risk of cutting tendons short, use of this approach has also reduced harvest time. Numbness was reduced initially with the short incision and has now been almost completely eliminated by the minimal retraction technique. Cosmesis and patient satisfaction have been excellent.

WHO SHOULD USE THIS TECHNIQUE? This technique is particularly desirable for the new or occasional HS harvester and has proven valuable to those in training programs. However, it will also facilitate the harvest and improve cosmesis for most experienced HS surgeons who now use the traditional approach—as it did for the author, who began to use it after fellowship training in hamstring ACLR and 6 years of practice performing the standard technique. Initially the incisions can be made larger. Cosmesis will still be better than with the traditional approach. The incisions can be reduced with experience if the surgeon wishes. 4HS grafts have now been shown to have excellent stability rates1 (see Chapter 69), and the harvest has been shown to be the chief obstacle to use of the technique. With this approach the surgeon can accomplish the harvest safely and reliably so that harvesting is no longer a significant factor in graft choice.

References 1. Prodromos CC, Joyce BT, Shi KS, et al. A meta-analysis of stability after anterior cruciate ligament reconstruction as a function of hamstring versus patellar tendon graft and fixation type. Arthroscopy 2005;21:1202–1208. 2. Williams RJ, III, Hyman J, Petrigliano F, et al. Anterior cruciate ligament reconstruction with a four-strand hamstring tendon autograft. J Bone Joint Surg Am 2004;86A:225–232. 3. Howell SM. Principles of hamstring fixation. In: ACL reconstruction: from graft choices and fixation to single and dual tunnel techniques. Instruction course presented at the meeting of the Arthroscopy Association of North America, Vancouver, BC, Canada, May 2005. 4. Prodromos CC, Han YS, Keller BL, et al. Posterior mini-incision technique for hamstring anterior cruciate ligament reconstruction graft harvest. Arthroscopy 2005;21:130–137. 5. Ferrari JD, Ferrari DA. The semitendinosus: anatomic considerations in tendon harvesting. Orthop Rev 1991;20:1085–1088. 6. Pagnani MJ, Warner JJ, O'Brien SJ, et al. Anatomic considerations in harvesting the semitendinosus and gracilis tendons and a technique of harvest. Am J Sports Med 1993;21:565–571. 7. Portland GH, Martin D, Keene G, et al. Injury to the infrapatellar branch of the saphenous nerve in anterior cruciate ligament reconstruction: comparison of horizontal versus vertical harvest site incisions. Arthroscopy 2005;21:281–285. 8. Spicer DDM, Blagg SE, Unwin AJ, et al. Anterior knee symptoms after four-strand hamstring tendon anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2000;8:286–289.

Technique for Harvesting a Mid-Third Patella Tendon Graft for Anterior Cruciate Ligament Reconstruction INTRODUCTION The middle third of the patella tendon (bone– tendon–bone) is frequently used as a graft to replace a torn anterior cruciate ligament (ACL). A segment of bone is taken from the tibial tuber­ cle. It is left attached to the distal end of the patella tendon. A segment of bone is taken from the inferior pole of the patella. It is left attached to the proximal end of the tendon. The graft is reversed and is pulled upward through the tibial tunnel, across the joint, and into the femoral tun­ nel. The leading end of the graft (the bone plug that was taken from the tibia) is fixed to the femur using an interference screw. The trailing end of the graft (the patella portion) is fixed in the tibial tunnel using an interference screw. Extra pieces of bone that were trimmed from the bone plugs are placed in the patella defect. The edges of the patella tendon are closed.

SKIN INCISION A vertical skin incision is made medial to the tib­ ial tubercle approximately 0.5 cm medial to the medial edge of the patella tendon (Fig. 14-1). The upper end of the incision begins near the level of the joint line. The incision is extended distally to the level of the lower end of the tibial tubercle, approximately 6 to 8 cm below the joint line. Do not place this vertical incision in the midline of the knee: this leaves an unsightly scar, and it is difficult to reach the tibial tunnel from this midline position. This anteromedial

incision is placed distally, which is necessary to allow positioning of the tibial guide and drilling of the tibial tunnel (Fig. 14-2). It is not necessary to extend the incision very far proximally beyond the level of the joint; when the knee is extended and a single spike retractor is placed at the superior pole of the patella, the patella is pushed distally. The patella can thus be reached through this short, distally placed incision. Bupivacaine 0.5% with epinephrine 1:200,000 is infiltrated subcutaneously along the edges of the incision. Dissection is carried out through the superficial fascial layer to reach the deep fascial layer.

14 CHAPTER

Bertram Zarins

EXPOSURE Incise the deep fascial layer lengthwise over the center of the underlying patella tendon. This deep fascial layer is thin but becomes even thinner over the tibial tubercle. Divide the deep fascial layer proximally to the level of the upper portion of the patella (Fig. 14-3). This exposes the under­ lying patella, patella tendon, and tibial tuberosity. Enlarge the prepatella bursa to gain access to the patella.

TAKING THE GRAFT The average width of the patella tendon is about 30 mm. An approximately 10-cm width of ten­ don, or one-third, is taken as a graft. A ⅜-inch osteotome (which is about 9 mm wide) can be 101

Anterior Cruciate Ligament Reconstruction

FIG. 14-1 The skin incision is made on the medial aspect of the right knee. The incision begins at the joint line and extends distally about 6 to 8 cm. Do not place the incision over the center of the tibial tubercle.

FIG. 14-3 The deep fascia is incised over the center of the tibial tubercle, patella tendon, and patella.

FIG. 14-2 The skin incision has been placed distally and medially to allow proper placement of the tibial drill guide.

used as a template for judging the width of the graft and bone plugs. An osteotome 3 cm in length is used to make two par­ allel vertical cuts in the tibial tubercle to fashion a 9-cm-wide bone plug (Fig. 14-4). The ⅜-inch osteotome is used to make a transverse cut in the bone at the level of the distal end of the graft. The resulting bone plug is about 30 mm in length. Use the wide osteotome to extend the cuts in the tibial tubercle proximal to the tibial tubercle almost to the level of the joint; otherwise, the plug might crack proximally near the tendon-bone junction. Drill a single small hole in the distal end of the tibial bone plug, slightly less than 1 cm from 102

FIG. 14-4 A 3-cm-wide osteotome is used to make two parallel cuts in the tibial tubercle to fashion a 9-mm-wide bone plug.

the end of the tibial bone plug (Fig. 14-5). Pass a single suture of #5 Fiberwire through the tibial bone plug. Apply traction to the tibial bone plug, and slightly incise the superficial surface of the patellar tendon in line with the tibial tubercle bone plug. Use your finger to sepa­ rate the edges of the patella tendon graft from the adjacent patella tendon (Fig. 14-6). This blunt dissection avoids cutting fibers of the patella tendon graft.

Technique for Harvesting a Mid-Third Patella Tendon Graft for Anterior Cruciate Ligament Reconstruction

14

FIG. 14-7 The single spike retractor has been placed at the superior pole of the patella and is used to lever the patella distally. The cutting current of the electrocoagulation devices is used to mark the proposed bone cut. FIG. 14-5 A hole is drilled in the bone plug that was taken from the tibial tubercle.

proposed cuts in the patella using electrocautery, which will achieve an 11-mm-wide plug that will be about 30 mm long (Fig. 14-8). Drill the corners of the graft to create round stress risers. Drill two small holes in the patella bone plug for later passage of sutures. Make the remaining cuts in the patella using the fine reciprocating saw to a depth of 1 cm (Fig. 14-9). To loosen the bone plug from the patella, use a ¼­ inch-wide curved osteotome inserted into the kerf at the superior end of the plug (Fig. 14-10). Never insert the osteotome into the medial or lateral kerfs along the edges of the patella bone plug, which will likely fracture the patella. Apply tension to the distal end of the graft, and

FIG. 14-6 The patella tendon is split in line with its fibers using a finger.

Insert a single spike retractor under the proximal edge of the skin incision. The prepatella bursa provides space to reach the superior pole of the patella. The spike of the retractor is set into the quadriceps tendon at the superior pole of the patella and is used to lever the patella distally (Fig. 14-7). Using the cutting current of the cautery device, mark the line of the proposed first cut in the patella (see Fig. 14-7). Use a fine reciprocating saw to cut a slot in the patella for a length of about 25 mm and to a depth of 1 cm. Insert a metal ruler into this kerf (the cut made by a saw) and use it as a guide from which to measure. Using the ⅜-inch-wide osteotome as a template, mark the

FIG. 14-8 A ruler has been placed in the kerf. A ⅜-inch-wide osteotome is used as a template, and electrocautery is used to mark out a bone plug 11 mm wide and 25 mm long.

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Anterior Cruciate Ligament Reconstruction

FIG. 14-9 After the corners of the graft have been drilled, a fine reciprocating saw is used to make superior and then lateral cuts in the bone plug.

FIG. 14-11 A ¼-inch curved osteotome is used from below to create a 1­ cm-thick bone plug from the patella.

FIG. 14-12 A sizer is used to fashion an 11-mm-diameter bone plug that was taken from the patella (the trailing end of the graft). FIG. 14-10 A ¼-inch curved osteotome loosens the upper end of the bone plug. Never put the osteotome into the medial or lateral kerfs to prevent fracturing the patella.

use the ¼-inch-wide curved osteotome from below (starting at the inferior pole of the patella) to lift the patella bone plug from its bed (Fig. 14-11).

FASHIONING THE GRAFT Use a bone cutter or rongeur to remove excess bone from both bone plugs to fashion a 9-mm-diameter bone plug from the tibial tubercle and an 11-mm-diameter bone plug from the patella (Fig. 14-12). Use a bone sizer to com­ press any excess cancellous bone. Do not use the bone sizer to compress cortical bone; doing so may fracture the patella. Place the extra pieces of bone into the defect in 104

the patella. Close the deep fascial layer over the patella to prevent the bone pieces from falling out. Leave the edges of the patella tendon defect open for the time being. At a side table, fashion the graft. To prevent dropping the graft, keep the suture that is attached to the graft wrapped around your little finger. Pass #5 Fiberwire sutures through each of the two holes and clamp the ends of the sutures. Use a 2–0 Vicryl running suture to tubularize the tendon at the end attached to the tibial bone plug (which will become the leading end of the graft) (Fig. 14-13). This will make it easier to place the interference screw into the femoral tunnel. Measure the total length of the graft and the lengths of the bone plugs. Use a colored marker pen to mark the bone-tendon junctions of the graft. Also mark the tendon side of the trailing end of the patella bone plug; this will aid in positioning the tibial interference screw on the opposite (cancellous) side of the plug (Fig. 14-14).

Technique for Harvesting a Mid-Third Patella Tendon Graft for Anterior Cruciate Ligament Reconstruction

14

FIG. 14-14 The mid-third patella tendon graft is about 10 cm long. The graft incorporates (in continuity) segments of bone from the inferior pole of the patella (9 � 30 mm) and from the tibial tubercle (11 � 25 mm). The bone-tendon junctions have been marked. The trailing end of the graft (tendon side) is marked. FIG. 14-13 The tendon of the leading edge of the graft is tubularized to allow easy placement of the interference screw in the femoral tunnel.

The final length of the graft is about 10 cm long. The leading end of the graft (taken from the tibial tubercle) is 9 mm in diameter and about 30 mm long. The trailing end of the graft (formerly patella) is 11 mm in diameter and about 25 mm long.

CLOSURE After the graft has been fixed, flex the knee to 90 degrees to achieve equal tension on the medial and lateral thirds of the patella tendon. Close the defect in the patella tendon using interrupted #0 Vicryl figure-eight sutures. Close the deep fascial layer.

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15

The Central Quadriceps Free Tendon for Anterior Cruciate Ligament Reconstruction

John P. Fulkerson

INTRODUCTION

CHAPTER

The central quadriceps has been used for anterior cruciate ligament reconstruction (ACLR) for more than 25 years.1,2 Stability results are similar to those with other autograft alternatives, but patients experience less pain and reach rehabilitation landmarks sooner.3 Staubli et al4,5 have studied the anatomy and biomechanical properties of the quadriceps tendon. We became interested in this ACL graft in the early 1990s, first using it with bone6 but later discovering that it is a desirable free tendon graft option7 for ACLR. We wanted to avoid the risk of postoperative problems noted with bone–tendon–bone–patella tendon graft harvest,8,9 were concerned about subtle weakness after taking out the medial hamstring tendons for ACLR in young athletes,10 and continue to worry about the possibility of prions in allograft tissue. We wanted to avoid these risks by using the central quadriceps free tendon (CQFT) for our ACLR. We confirmed and later reported the strength of the quadriceps tendon after harvesting the graft.11 Our experience has remained very positive as we begin our 10th year with the CQFT graft. Also, patients frequently come into our office impressed with how little postoperative pain and difficulty they have compared with bone–tendon–bone and hamstring ACLR patients they encounter in physical therapy, as noted by Joseph et al3 in their short-term recovery study of ACLR patients.

106

TECHNIQUE We use the CQFT graft in all patients except those who specifically request another graft type, usually an allograft. To harvest the CQFT, make a short 1.5- to 2-inch incision from the mid proximal patella upward (Fig. 15-1), and retract to view the quadriceps tendon. Retract slightly medially and note the vastus medialis obliquus (VMO). The graft should be taken preferentially from the thicker medial part of the quadriceps tendon but started proximally by retracting upward to the proximal VMO where the first incision is placed. Use a #10 scalpel blade and draw it distally at a 6- to 7-mm depth (just slightly less than the breadth of a #10 blade). The medial border of the graft then will usually be about 5 to 8 mm from the VMO at the level of the proximal patella. Place the second incision 9 to 11 mm lateral to the first at the level of the proximal patella and extend it proximally, keeping the blade at 90 degrees to the quadriceps tendon and at a 6- to 7-mm depth (the quadriceps tendon is about 9 mm thick). After placing these incisions, place the tip of a hemostat at the desired depth beneath the CQFT, and spread the hemostat to separate the CQFT posterior fibers within the substance of the quadriceps tendon. This leaves a thin 1 mm of posterior quadriceps tendon attached to the synovium of the suprapatellar pouch. If the joint has been entered, the defect is then easily closed with this remaining tissue and synovium.

The Central Quadriceps Free Tendon for Anterior Cruciate Ligament Reconstruction

FIG. 15-1 Exposure for quadriceps tendon graft harvest.

FIG. 15-2 Release of the proximal end of the quadriceps tendon graft.

Properly done, you now have a piece of tendon that is about 6 to 7 mm thick and includes portions of the rectus and intermedius tendons. Note that there is a cleavage plane between these two components of the quadriceps tendon. Keep spreading at the desired depth, and then dissect the tip of the graft at its insertion into the patella and release it without cutting any of the surrounding quadriceps tendon. Grasp the released end of the quadriceps tendon with a uterine T clamp, and further dissect it proximally using a combination of blunt stripping and careful sharp dissection. We usually place two whipstitches12 with at least one Fiberwire (Arthrex, Naples, FL) in the released end and use this for traction during the dissection. Release the CQFT graft proximally at 7 to 8 cm from the distal end. May scissors work best in our hands (Fig. 15-2).

the pouch—you have a good 7 mm of tendon thickness to work with in almost every patient, but do not cut any deeper. If you do, cut all water flow, finish the harvest leaving the posterior fibers of quadriceps tendon, and run a continuous Vicryl suture along the synovium to close the defect before resuming arthroscopy. Releasing the graft distally is easiest with a #15 scalpel blade. While retracting with the hemostat, you can define the insertion point of the graft on the patella nicely and release only the graft portion of the quadriceps tendon from the top of the patella. A hemostat works well for defining the posterior border of the graft spread generously. If you do not obtain a thick-enough graft depth initially, place the hemostat a little deeper and define a larger, thicker graft as needed. The author prefers to use almost entirely blunt dissection after defining the borders, but a few careful clips with Metzenbaum scissors to aid the graft removal is usually helpful. Visualize all sides of the graft while stripping it out. Keep the knee flexed to 90 degrees, with tension on the quadriceps tendon, during the entire harvest. Use a uterine T clamp to grasp the end of the graft and then put #5 whipstitches in the free end, before stripping the graft proximally, to apply tension for the stripping. Use Mayo scissors to release the graft proximally under direct vision while retracting skin proximally and pulling the graft distally. As you release it, be careful not to flip the graft back into your face mask with the tension. Take the graft to the back table and keep it under tension for whipstitching the other end, sizing it, and preparing it for placement in the knee.

TROUBLESHOOTING CENTRAL QUADRICEPS FREE TENDON HARVEST At first, harvesting the CQFT graft can seem a bit daunting until the surgeon becomes familiar with the anatomy, depth, and extent of the tendon. It is a very large, thick, and forgiving graft source. The quadriceps tendon is thickest near the VMO, so the harvest should be as close to the VMO as possible while avoiding all but the proximal muscle fibers of the VMO. Thus, think of the harvest as midline, starting at the proximal central aspect of the quadriceps tendon but 1 or 2 mm medially. When first harvesting the graft, be sure to make an adequate incision. The incision gets smaller with experience. Define the graft borders carefully and try to avoid entering

15

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Anterior Cruciate Ligament Reconstruction

FIG. 15-3 Sizing of the quadriceps tendon graft.

FIXATION OF THE CENTRAL QUADRICEPS FREE TENDON GRAFT We take the CQFT graft to the back table and place two sets of #5 whipstitches in each end using a combination of Ethibond or Ticron and Fiberwire. McKeon et al have shown that it is not necessary to place more than two whipstitch throws in each side of the tendon.12 Use sizing cannulas (Fig. 15-3) to determine the size of the graft and the tunnels you will drill in the tibia and femur. In most cases, the graft will fit snugly into 8- or 9-mm tunnels. Next, place a circumferential mark on the graft at the point where it will exit the femoral socket (we like 2 cm of CQFT in the femoral socket). We prefer an Endobutton on the femoral end (Fig. 15-4), tying the #5 sutures (four strands off the end of the graft) after measuring the depth

FIG. 15-5 Bottom view of the central quadriceps free tendon (CQFT) graft in the tibial tunnel.

of the femoral tunnel such that the distance from the Endobutton to the marked femoral socket exit point on the graft is the same as the tunnel length, measured with the Endobutton depth gauge. Tie the sutures together (we use a Graftmaster to hold the graft and Endobutton during this process) with the knot just adjacent to the tendon graft (tying it elsewhere may cause problems in full deployment of the Endobutton). We pull the graft into the tunnels and deploy the Endobutton in the usual fashion, using a #5 suture and then a #2 in the other end to flip the Endobutton after it is through the lateral femur.

Femoral socket

#5 leading suture

#2 trailing suture

⭓7 cm

Tibial tunnel/socket screw/washer FIG. 15-4 Quadriceps tendon with Endobutton.

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Knot close to the graft to avoid problem with Endobutton

The Central Quadriceps Free Tendon for Anterior Cruciate Ligament Reconstruction

15

We use a biointerference screw that is one size larger than the tunnel size for tibial side fixation. After thoroughly cycling the graft in the knee and while maintaining tension on the graft, flex the knee 20 degrees and insert the biointerference screw over a guidewire that is held in place just anterior to the graft in the tibial tunnel. Be sure not to push the screw and graft, but rather advance it by turning only after seating the screw. We prefer to have the tip of the screw 5 to 8 mm back from the intercondylar notch and recommend viewing the screw/graft construct from below to confirm proper placement (Fig. 15-5). A button may be tied over the tibial tunnel for added fixation if desired.13 We have been pleased with these fixation methods (Figs. 15-6 and 15-7).

FIG. 15-7 Quadriceps tendon with bone or biointerference disk and screw.

References

FIG. 15-6 Central quadriceps free tendon ACL reconstrution.

1. Marshall JL, Warren RF, Wickiewicz TL, et al: The anterior cruciate ligament: a technique of repair and reconstruction. Clin Orthop Relat Res 1979;Sep:97–106. 2. Blauth W: Die zweizugelige Ersatzplastik des Vorderen Kreuzband der Quadricepssehne. Unfallheilkunde 1984;87:45–51. 3. Joseph M, Fulkerson J, Nissen C, et al: Short-term recovery after anterior cruciate ligament reconstruction: a prospective comparison after three autografts. Orthopedics 2006;29:243–248. 4. Staubli HU, Schatzmann L, Brunner P, et al: Quadriceps tendon and patellar ligament: cryosectional anatomy and structural properties in young adults. Knee Surg Sports Traumatol Arthrosc 1996;4:100–110. 5. Staubli HU, Schatzmann L, Brunner P, et al: Mechanical tensile properties of the quadriceps tendon and patellar ligament in young adults. Am J Sports Med 1999;27:27–34. 6. Fulkerson JP, Langeland R: An alternative cruciate reconstruction graft: the central quadriceps tendon. Arthroscopy 1995;11:252–254. 7. Fulkerson J: Central quadriceps free tendon for anterior cruciate ligament reconstruction. Oper Tech Sports Med 1999;7:195–200. 8. Viola R, Vianello R: Three cases of patella fracture in 1320 anterior cruciate ligament reconstructions with bone-patellar tendon-bone autograft. Arthroscopy 1999;15:93–97. 9. Sachs RA, Daniel DM, Stone ML, et al: Patellofemoral problems after anterior cruciate ligament reconstruction. Am J Sports Med 1989;17:760–765. 10. Marder RA, Raskind JR, Carroll M: Prospective evaluation of arthroscopically assisted anterior cruciate ligament reconstruction. Patellar tendon versus semitendinosus and gracilis tendons. Am J Sports Med 1991;19:478–484. 11. Adams D, Mazzocca A, Fulkerson J: Residual strength of the quadriceps versus patellar tendon after harvesting a central free tendon graft. Arthroscopy 2006;22:76–79. 12. McKeon B, Heming J, Fulkerson J, et al: The Krackow whipstitch: a biomechanical evaluation of changing the number of loops versus the number of sutures. Arthroscopy 2006;22:33–37. 13. Nagarkatti DG, McKeon BP, Donahue BS, et al: Mechanical evaluation of a soft tissue interference screw in free tendon anterior cruciate ligament graft fixation. Am J Sports Med 2001;29:67–71.

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16 CHAPTER

Alberto Gobbi Ramces Francisco

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PART C HAMSTRING GRAFT CONFIGURATIONS

Hamstring Anterior Cruciate Ligament Reconstruction with a Quadrupled or Tripled Semitendinosus Tendon Graft INTRODUCTION A wide variety of techniques and graft types are now available for the reconstruction of the anterior cruciate ligament (ACL). Years of clinical and surgical experiences gained by surgeons together with the development and modification of the various instrumentations have greatly contributed to the better results currently reported in literature. However, disagreement persists among experts with regard to the ideal technique and graft type most suitable for reconstruction. Currently, most surgeons use either the hamstring graft or the bone–patellar tendon– bone (BPTB) graft for ACL reconstruction. Previous studies have demonstrated the advantages and disadvantages of using one type of graft over the other. However, recent investigations have confirmed that comparable outcomes can be achieved with either of these two graft types.1–3 Inherent advantages cited with the use of hamstring grafts include its strength, decreased incidence of donor site morbidity, easier rehabilitation, smaller incisions, and better cosmesis.1,2,4 With BPTB graft, the strong bone-to-bone fixation and the faster healing achieved with the bone plugs at the graft’s end1,5 remain important advantages. In this chapter, we describe the technique of using a quadrupled semitendinosus tendon graft harvested with a bone block for the reconstruction of a torn ACL.

Studies have demonstrated that this type of graft configuration is capable of producing a clinically stable construct that allows recovery of normal limb strength and early return to active sports and results in low donor site morbidity.

SCIENTIFIC RATIONALE FOR A QUADRUPLED CONSTRUCT Hamstring grafts have gained popularity among surgeons due to the well-documented higher donor site morbidity when patellar tendon graft is used.6–8 Although prospective randomized studies comparing patellar tendon and hamstring grafts demonstrated no significant difference in final outcome, the apparent advantages offered by hamstring grafts remain appealing to surgeons. Previous concerns related to the hamstring tendon’s viability have long been dismissed, and studies comparing different graft types and configurations have demonstrated that failure load and stiffness values for four-stranded hamstring tendon grafts are higher than values reported for the natural ACL (2160N, 242 N/mm), 10-mm-wide patellar tendon grafts (2977N, 455 N/mm), and 10-mm-wide quadriceps tendon grafts (2353N, 326 N/mm).9,10 On the other hand, concerns related to hamstring graft incorporation within the tunnel was addressed with Morgan’s11 introduction of an “all inside” technique using bone–hamstring– bone composite graft. Therefore to address the

Hamstring Anterior Cruciate Ligament Reconstruction with a Quadrupled or Tripled Semitendinosus Tendon Graft concerns related to morbidity and delayed graft incorporation, we developed a technique that combines the advantages of a decreased donor site morbidity by using only one hamstring tendon (semitendinosus) with the possibility of achieving faster graft–tunnel incorporation by including a bone block with the distal limb of the semitendinosus tendon during harvest.1,12,13

SURGICAL TECHNIQUE The surgery can be performed under spinal anesthesia or general anesthesia. The patient is positioned supine on the operating table, and the tourniquet is placed as high as possible on the thigh to allow sufficient distance from the exit point of the Beath needles in the lateral thigh. The tourniquet is inflated only during graft harvest. A thigh support is placed at the level of the tourniquet cuff while a foot bar is positioned at the end of the table to enable the knee to be fixed at 90 degrees of flexion during surgery while at the same time still allowing free range of motion. A 3-cm vertical incision centered approximately 5 cm below the medial joint line, midway between the tibial tubercle and the posteromedial aspect of the tibia, is performed. The sartorial fascia is incised, and the semitendinosus tendon is dissected and detached proximally with a tendon stripper. The distal limb of the tendon is detached along with a tibial bone plug and periosteum with the use of an osteotome. To achieve the desired 7-cm quadrupled graft construct (2 cm inserted in the femoral tunnel, 3 cm intraarticular, and 2 cm inserted in the tibial tunnel), the required minimum tendon length would be 28 cm (range 28–30 cm) (Fig. 16-1). Alternatively, semitendinosus tendons that are shorter than 28 cm can be prepared in a tripled configuration.

Graft Preparation Quadrupled Semitendinosus Graft At the back table, all the muscle tissues attached to the tendon are removed with the use of a curette. Once devoid of excess tissues, the tendon is folded in a quadrupled fashion with the bone plug tied outside. Prior to suture placement on the tendon construct, the depth of the femoral tunnel is measured to determine the appropriate size of the Endobutton-CL

FIG. 16-1 The semitendinosus tendon harvested with a bone block attached on one end. The ideal length for the graft should be at least 28 cm to allow the preparation of a quadrupled construct.

16

(Smith & Nephew, Endoscopy, Andover, MA) to be used. Once the proper size is chosen, the Endobutton is then positioned in the quadrupled construct’s end where the bone block is located. Both ends of the graft are then whipstitched using #5 nonabsorbable sutures. A polyester tape is then knotted at the other end of the graft (Fig. 16-2, A, B). Measurement of the graft diameter follows, using 0.5-mm increment sizers to match this with the diameter of the femoral and tibial tunnels. Once in place, the grafts are pretensioned and preconditioned prior to fixation with cyclical flexion and extension of the knee under maximum manual tension.1,6

Tripled Semitendinosus Graft (Alternative Option for Short Semitendinosus Grafts) Harvested semitendinosus tendons with a total length of less than 28 cm can be prepared in a tripled configuration. Once the excess tissues are removed, both ends of the semitendinosus tendon are whipstitched using #5 nonabsorbable sutures (Fig. 16-3, A). The tendon is then folded in three parts (three limbs) to determine the graft’s length and to approximate the size of the Endobutton-CL to be used. In general, we usually use either a 20- or 25-mm EndobuttonCL, considering that we have a tunnel length of about 40 to 45 mm. On the end of the graft where the bone plug is located, the free ends of the suture are used to tie a knot around the Endobutton-CL so that it becomes attached to the graft (Fig. 16-3, B). The other end of the graft is then passed through the loop of the EndobuttonCL as the tendon is folded in three parts. After passing through the Endobutton-CL, the suture at the free end of the graft is separated and positioned in such a way that it would catch the looped tendon at the opposite end (Fig. 16-3, C). With this configuration the diameter of this tripled semitendinosus is measured to make sure that it corresponds with the femoral and tibial tunnels. Prior to the final fixation, routine pretensioning and preconditioning of the graft are performed.

Arthroscopic Anterior Cruciate Ligament Reconstruction A standard anterolateral portal is created through which the arthroscope is inserted followed by an anteromedial portal where instruments can be introduced. While the graft is being prepared at the back table, tunnel preparations are completed. The tibial tunnel is prepared with the Acufex aimer set at 45 degrees with 70 degrees of inclination from the sagittal plane. During tibial tunnel reaming, a bone plug is obtained through the coring system used. On the other hand, the femoral tunnel is drilled in the 10:30 position for the right knee. Femoral fixation is achieved with the Endobutton connected to the graft while tibial fixation is obtained with an 8-mm titanium Fastlok device 111

Anterior Cruciate Ligament Reconstruction Endobutton

Bone plug 9–10 mm

BONE Quadrupled semitendinosus autograft

A

FIG. 16-2 Diagram (A) and actual quadrupled semitendinosus construct with Endobutton on one end and polyester tape in the other end (B). The bone block is positioned and stitched outside the graft.

Bone plug

Semitendinosus autograft

A Endobutton

Bone plug

Semitendinosus autograft

B Endobutton

Bone plug

Tripled semitendinosus autograft

C FIG. 16-3 A, Diagram of the semitendinosus tendon with both ends sutured. B, Endobutton-CL is knotted on the end where the bone plug is located; the free end of the graft is then passed through the Endobutton-CL to form the three limbs. C, The free ends of the suture are separated and hooked around the opposite loop to complete the configuration.

(Neoligaments, Leeds, United Kingdom), which is also connected to the graft with a quadrupled polyester tape. Finally, the bone block previously obtained from reaming the tibia is press-fitted in the tibial tunnel (Fig. 16-4). Postoperatively, rehabilitation is commenced according to the protocol described by Rosenberg and Pazik.14 112

Clinical Results In a previous study10 of 100 patients who underwent ACL reconstruction using this technique, it was demonstrated that the average postoperative VAS pain score was 5 (range 2–7), with 90% of the patients discharged within 24 hours

Hamstring Anterior Cruciate Ligament Reconstruction with a Quadrupled or Tripled Semitendinosus Tendon Graft

Endobutton-CL Bone block attached to ST Quadrupled semitendinosus Bone block Polyester tape Fastlok tibial fixation

FIG. 16-4 Diagram of quadrupled semitendinosus with bone (QSTB) anterior cruciate ligament reconstruction. Femoral fixation was achieved with a continuous loop Endobutton while tibial fixation was carried out with a Fastlok device augmented by a bone block impacted in the tibial tunnel.

following the procedure. This finding was consistent with the subjective IKDC scores in which an average rating of 80% was obtained. Six months following the procedure, 10% of patients had noted pain over the tibial hardware with associated hypoesthesia over the surgical incision. Clinical examination at final evaluation demonstrated 90 patients with less than 1 cm difference in thigh circumference, two patients with extension lag of 6 degrees, and another two patients with flexion loss of 10 degrees. Kneeling test was positive only in 7% of these patients, while the postoperative Lachman test was negative in 90% (þ1 in nine cases and þ2 in one case). Sensory changes were evident in 30% of patients at 3 months with only 10% having localized hypoesthesia at the proximal third of the tibia at final evaluation. Subsequent radiographs and magnetic resonance imaging (MRI) revealed that only three tibial tunnels and four femoral tunnels were widened more than 25% from the original diameter. However, all these cases retained an anterior laxity that was less than 3 mm and subjectively rated their knees above 80%. MRI studies using T1- and T2-weighted transaxial sequences in 30 patients at 3 and 6 months demonstrated graft incorporation in the tunnels with evidence of viability. Computerized analysis of knee laxity at final followup showed 90 cases to have a side-to-side difference of less than 3 mm, nine cases with 3 to 5 mm of difference, and one case with more than 5 mm of difference. The mean side-toside difference was 1.9 mm (1.7 mm in males and 2.3 mm in females).

16

Isokinetic tests were not significantly different between 6 and 12 months (P ¼ 0.6526). The hamstring/quadriceps ratio was slightly lower in the operated limbs compared with the normal limbs at all test intervals and speed settings but was not statistically significant (P ¼ 0.9576). Neither external (P ¼ 0.6181) nor internal rotation strength (P ¼ 0.3681) demonstrated significant deficits at 6 and 12 months postreconstruction when compared with the normal limb. Knee evaluation scores demonstrated the following: IKDC (A, 66%; B, 24%; C, 9%; D, 1%); Noyes, 87.9 (range 65–100); Lysholm, 93 (range 70–100); and preinjury and postoperative Tegner, 6.1 and 6.0, respectively.

Complications A few patients noted pain on incidental contact at the tibial side, which eventually required removal of the Fastlok device. In five cases, on second-look arthroscopy the grafts remained viable and functional. In addition, two cases had transient superficial wound infection that resolved with antibiotic treatment. In one case, a deep streptococcal infection was documented, which required arthroscopic lavage and débridement. Further evaluation demonstrated chondral damage with loss of motion.

CONCLUSION The technique of using a quadrupled bone-semitendinosus graft construct for ACL reconstruction has results comparable to other techniques in terms of restoration of knee stability, recovery of normal limb strength, and patient satisfaction. This technique effectively combines the biological principles of healing with bone-to-bone contact and high cross-sectional graft area. It provides a viable alternative to other graft types, particularly in patients with preexisting patellar or extensor apparatus problems.

References 1. Gobbi A, Zanazzo M, Tuy B, et al. Patellar tendon versus quadrupled bone semitendinosus ACL reconstruction: a prospective investigation in athletes. Arthroscopy 2003;19:592–601. 2. Aune AK, Holm I, Risberg MA, et al. Four-strand hamstring tendon autograft compared with patellar tendon autograft for anterior cruciate ligament reconstruction: a randomized study with two year follow-up. Am J Sports Med 2001;29:722–728. 3. Prodromos CC, Han YS, Keller BL, et al. Stability results of hamstring anterior cruciate ligament reconstruction at 2- to 8-year follow-up. Arthroscopy 2005;21:138–146. 4. Shelbourne KD. Donor site problems after anterior cruciate ligament reconstruction using the patellar tendon graft. J Sports Traumatol Rel Res 1995;17:120–128. 5. Pinczewski LA, Clingeleffer AJ, Otto BD, et al. Case report: integration of hamstring tendon graft with bone in reconstruction of the anterior cruciate ligament. Arthroscopy 1997;13:641–643.

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Anterior Cruciate Ligament Reconstruction 6. Cooley VJ, Deffner KT, Rosenberg TD. Quadrupled semitendinosus anterior cruciate ligament reconstruction: 5 year results in patients without meniscus loss. Arthroscopy 2001;17:795–800. 7. Corry IS, Webb JM, Clingeleffer AJ, et al. Arthroscopic reconstruction of the anterior cruciate ligament. A comparison of patellar tendon autograft and four-strand hamstring tendon autograft. Am J Sports Med 1999;27:444–454. 8. Maeda A, Shino K, Horibe S. Anterior cruciate ligament reconstruction with multi stranded autogenous semitendonosus tendon. Am J Sports Med 1996;24:504–509. 9. Brown CH Jr, Sklar JH. Endoscopic anterior cruciate ligament reconstruction using quadrupled hamstring tendons and Endobutton femoral fixation. Tech Orthop 1998;13:281–298. 10. Weiler A, Scheffler S, Gockenjau A, et al. Different hamstring tendon graft fixation techniques under incremental loading conditions (abstract). Arthroscopy 1998;14:425–426.

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11. Morgan C. The bone-hamstring-bone composite autograft for ACL reconstruction. Presented at the AAOS, New Orleans, Month, 1994. 12. Gobbi A, Panuncialman I. Quadrupled bone-semitendinosus ACL reconstruction: a prospective clinical investigation in 100 patients. J Orthopaed Traumatol 2003;3:120–125. 13. Gobbi A, Domzalski M, Pascual J, et al. Hamstring anterior cruciate ligament reconstruction: is it necessary to sacrifice the gracilis? Arthroscopy 2005;21:275–280. 14. Rosenberg TD, Pazik JT. Anterior cruciate ligament reconstruction with quadrupled semitendinosus autograft. In Parisen JS (ed). Current techniques in arthroscopy. Current medicine. Philadelphia, 1996, Churchill Livingstone, pp 77–78.

2ST/2Gr, 4ST, and 3ST/2Gr Techniques: Deciding Which Hamstring Configuration to Use INTRODUCTION Use of the four-strand hamstring (4HS) graft using the semitendinosus (ST) with or without the gracilis (Gr) has increased dramatically in the past 5 years. This graft has long been considered to have lower morbidity than bone–patellar tendon–bone (BPTB) grafts. After reports showed its clinical stability results to meet or exceed those of the BPTB,1–7 its use began to significantly increase. 2ST/2Gr is the most commonly used hamstring graft, followed by 4ST. However, a total of six different multistrand hamstring graft configurations have been reported and are in current use. This chapter will describe the advantages of each configuration according to the five parameters involved in decision making. Graft preparation techniques will also be described.

THE PARAMETERS FOR CHOOSING A HAMSTRING GRAFT CONFIGURATION Five parameters (Table 17-1 and see later discussion) will drive decision making regarding which HS graft, or soft tissue graft in general, will be used. The first three parameters are available graft length in the tunnel, the type of fixation that can be used, and whether the gracilis must be sacrificed. These are generally themost important considerations to most orthopaedic surgeons. The last two parameters, relative graft strengths and whether it is double-bundle compatible, are important to some.

1. Is the Graft Long Enough to Allow Adequate Tunnel Healing?

17 CHAPTER

Chadwick C. Prodromos

In our experience, ST harvests range in length from 24 to 34 cm, with most being between 26 and 30 cm in usable length. Intraarticular anterior cruciate ligament (ACL) length is 3 to 3.5 cm.8 Roughly 1 cm of shortening occurs as a result of whipstitch implantation. Thus, for example, a 27-cm graft will be 26 cm after suturing. When quadrupled, this length is 6.5 cm. Subtracting 3 cm for the intraarticular portion leaves 3.5 cm of graft for both tunnels, or about 1.75 cm or 17.5 mm for each tunnel. If the ST is only doubled and not quadrupled, the resultant 12 cm or longer graft can provide 4 cm or more of graft length in each tunnel. Some surgeons9 will use 4ST if the ST is 30 cm or longer and 2ST/2Gr if the ST harvest is less than 30 cm.

The Argument for Greater Length Being Necessary Many surgeons are not comfortable with graft lengths of less than 2 cm in each tunnel. The principal argument in favor of this is the study by Greis et al10 that shows greater pull-out strength as graft length increases.

The Argument for Less Length Being Sufficient However, there is a significant body of data indicating that 15 mm or even less graft in a tunnel is acceptable. A recent study by Zantop et al in goats using Endobutton fixation showed 115

Anterior Cruciate Ligament Reconstruction TABLE 17-1 Advantages and Disadvantages of Various Graft Configurations Strength

Sacrifice Gracilis

Interference Screw Compatible

Graft Length in Tunnel

Two-Bundle Compatible

2ST/2Gr

High

Yes

Yes

Long

No

3ST

Moderate

No

No

Medium

No

3ST/2Gr

High

Yes

No

Medium

Yes

3ST/3Gr

High

Yes

No

Medium

Yes

4ST

High

No

No

Short

Yes (?)

4ST/4Gr

High

Yes

No

Short

Yes

Gr, Gracilis; ST, semitendinosus.

no difference in load to failure between 15 mm and 25 mm of graft in the tunnel.11 A study by Yamazaki et al in dogs using whipstitch cortical screw post fixation showed no difference between 5 mm and 15 mm.12 Equally persuasive in favor of shorter lengths being acceptable is the clinical experience of a number of experienced surgeons such as Rosenberg and Cooley2 and Paulos13 who have had excellent results using 15-mm grafts. We have also used 15 mm as a minimum without a graft failure.

2. Is the Graft Long Enough to Allow Direct Tibial Fixation or Only Indirect? Direct fixation includes all interference screw and interference screw–based techniques such as Intrafix and techniques that rely on direct friction with the graft, such as the WasherLoc. Indirect fixation uses a fabric interface with the graft such as the whipstitch post technique or Fastlok. As seen in Table 17-1, use of the Gr as well as the ST is necessary to be certain of a long-enough graft to ensure the use of direct fixation techniques.

3. Is the Gracilis Sacrificed? The Gracilis Is not Really a Hamstring One argument against the 2ST/2Gr graft is that it disables not one but two hamstring muscles because the Gr is also harvested in addition to the ST. However, the Gr is not really a hamstring. Gray’s Anatomy14 lists only three hamstring muscles: the biceps femoris, semimembranosus, and ST. All are innervated by the sciatic nerve; all flex the knee. The Gr is not listed as a hamstring. Rather, the Gr is listed with the adductors longus, brevis, and magnus as “medial femoral muscles.” All of these muscles, including the Gr, are innervated by the obturator nerve. The gracilis’ action is listed as “adducts the thigh.” Thus, the loss of the Gr is not the loss of a second hamstring. Rather, it is 116

the loss of an accessory adductor, much as the loss of the ST is the loss of an accessory hamstring.

What Is Lost by Harvesting the Gracilis in Addition to the Semitendinosus? Chapter 67 reviews strength after hamstring harvest. Hamstring strength can be restored in virtually 100% of patients in our experience. Specific testing has noted a small decrease in peak flexion torque at high flexion angles and decreased tibial internal rotation strength in flexion; however, no clinical deficit has ever been reported in function as a result of the addition of Gr harvest relative to ST alone. On theoretical grounds, some have avoided Gr harvest in sprinters and soccer players.15 However, performance deficits or subjective complaints have not been reported in this group. Anecdotally, we have performed bilateral 2ST/2Gr in a professional soccer player with excellent subsequent performance.

4. How Strong Is the Graft? Using the data from the classic study of Noyes et al16 in which the ST was 70% of the strength of the native ACL and the Gr was 49% of the strength, extrapolated hamstring graft strengths can be estimated. The 4ST would be 280%, the 2ST/2Gr would be 238%, the 3ST would be 210%, and the 2ST would be 140%. The 4ST and 2ST/ 2Gr have produced very high stability rates in clinical series.2–7 The 2ST has been associated with low rates, although this may well be largely due to the outmoded fixation that was used when those studies were done.17–19 Regardless of whether this is true, few surgeons today are comfortable with only a 2ST graft. The 3ST graft has produced high stability in some20 but not all21 series. This mixed clinical performance and the lower strength of the graft coupled with the increased complexity of using an odd-stranded graft in the femur has resulted in this graft being seldom used.

2ST/2Gr, 4ST, and 3ST/2Gr Techniques: Deciding Which Hamstring Configuration to Use

5. Is the Graft Double-Bundle Compatible? Yasuda et al22 have reported a six-strand, double-bundle technique with 3ST/3Gr, as described in Chapter 22. Christel uses a 2ST anteromedial (AM) bundle and either a 2Gr or 3Gr (if the Gr is small) posterolateral (PL) bundle, as described in Chapter 23. Zhao et al have reported a 4ST AM and 4Gr PL bundle eight-strand technique.23 Generally, excellent stability has been reported with these techniques. As with the later-described 5HS single-bundle technique, 6HS and 8HS techniques have not seemed to have the problems associated with the large size of these grafts, which are significantly larger than the native ACL. 2ST/2Gr has generally not been used in a double-bundle configuration. Single-bundle techniques use primarily AM bundle positioning. This has produced high success rates. The argument for double-bundle techniques supposes that the addition of a PL bundle can only help stability. However, PL bundle techniques are new and questionable to many. If the AM bundle is significantly weakened to provide a graft for the PL bundle, then the entire graft may be too weak if the PL technique is indeed not providing significant additional strength. Taking the Gr away from the AM bundle would leave only a 2ST graft, which alone has performed poorly in the literature in the past. It would seem safer to leave a stronger AM bundle, at least a 3ST graft, which would then be augmented by the PL bundle. Gobbi has reported excellent success with a 2ST AM bundle, but he has used the stronger 2ST graft rather than 2Gr for a PL bundle (see Chapter 24).

GRAFT PREPARATION TECHNIQUES 2ST/2Gr Graft Preparation Technique Using Endobutton Femoral and Whipstitch Posttibial Fixation

A sizer is slipped down the over the loop of the quadrupled graft for a distance of about 3 cm to ascertain the size of this femoral end separately from the tibial. We then add 0.5 to 1 mm of size to the tibial measurement to account for the greater bulk that will result from the second whipstitch when it is put into the paired proximal ends of the tendons after their length is determined. The tibial and femoral tunnels are then drilled using these tendon girth measurements.

Calculating the Optimal Length for the Graft If sufficient length exists, we will try to obtain 2.5 to 3 cm of graft in the femoral socket but will accept as little as 15 mm as described. Approximately 3.5 cm of intraarticular length and 3 cm of tibial length are then added to the calculation so that the usual graft will be about 9.5 cm in length. The graft is then cut to the necessary length. In this example the graft would be cut at 20 cm in length because 0.5 cm of shortening usually occurs between the insertion of the second whipstitch and the folding of the graft in the Endobutton. Thus, this 20-cm graft when doubled will be 10 cm in theory but closer to 9.5 cm in practice. However, if the femoral tunnel is shorter we will make the graft correspondingly shorter as well. In this example, if the femoral socket were 1.5 cm we would add 3.5 cm intraarticular and 3 cm tibial for a length of 8 cm. In theory this would require a 16-mm graft, but again we would add 1 cm to make it 17 mm in length. We restrict the graft length so that the graft will not have excessive length and abut the cortical screw post we use, resulting in an inability to create tension in the graft. In making these calculations, one can always assume the tibial tunnel to be at least 3 cm in length, and usually it is 4 to 5 cm in length. If any question exists in the surgeon’s mind, the intraarticular length and tibial tunnel length can be easily directly measured using the longdepth gauge in the Endobutton system or by other means.

Cleaning and First Whipstitch Implantation

Second Whipstitch Implantation and Trimming

After harvest the tendons should be cleaned of muscle tissue. We place whipstitches (see Chapter 42) in the combined tibial attachment of #5 braided nonabsorbable or #2 braided high-strength nonabsorbable suture such as Fiberwire (Arthrex, Naples, FL) or ultra-braid (Smith & Nephew, Andover, MA). We do not cut the graft at this point and do not whipstitch the other end. It is better to determine length once tunnel lengths have been determined.

Once the appropriate length has been determined, the two free proximal ends of the graft are doubled and a hemostat is clamped just beyond the desired length. The extra graft is cut off with a 15 blade scalpel, with the hemostat left in place on the doubled ends of the graft. The other whipstitch is then woven into the graft. The hemostat is removed after the second suture pass. Excess graft is carefully then trimmed from both ends. Removing “dog ears” will facilitate smooth graft passage. A snug fit is desirable, but do not try for too tight a fit or the graft will be traumatized during passage or may not pass at all. The graft is now ready for passage and fixation.

Sizing the Graft The graft is then sized. Usually the femoral end where the graft is looped will be about 1 mm thinner than the tibial end.

17

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Anterior Cruciate Ligament Reconstruction

TROUBLESHOOTING What if Either the ST or Gr Is Cut Too Short to Double? We have not had this occur using the posterior mini-incision harvest technique (see Chapter 13). However, if graft length is questionable, the first step should be to precisely measure the intraarticular length. The minimum graft we have used is this length plus 15 mm for each of the tibial and femoral tunnels. Thus, a 30-mm intraarticular length would allow a 30 þ 15 þ 15 ¼ 60 mm total graft. Six centimeters doubled is 12 cm. Adding 1 cm for shortening yields a 13-cm graft. Thus, all that should be necessary for most knees for a 4ST/Gr graft is a total length of 13 cm or 14 cm, allowing for measurement error. If the surgeon has this length, then he or she should be fine to proceed. If either the ST or Gr is shorter than this length, then the surgeon should plan to triple the other tendon to add to the single short limb of the short tendon. The two possibilities would thus be either 3ST/1Gr (stronger than 2ST/2Gr) or 1 ST/3Gr (not as strong as 2ST/2Gr but more than sufficiently strong). We would then implant whipstitches in the free ends. Whipstitch post fixation or Endobutton could then be used for femoral fixation. Cross-pin fixation would generally be difficult without the ability to loop each graft.

What if the Graft Is Too Big to Pass? The easiest first step is to trim the graft at the edges or elsewhere and try again. If it still will not pass, then the tunnel or tunnels must be enlarged slightly.

FIVE STRAND USING 3ST/2Gr Surgical Technique The ST and Gr are harvested in the usual fashion. The ST is measured and, provided that it is at least 22.5 cm in length, the proximal one-third is sectioned from the distal two-thirds. For example, a 24-cm ST would be cut to leave 16 cm intact with its insertion, and the proximal 8 cm would be cut off to use as a single limb. This tissue would otherwise be discarded. In our experience the ST is always at least 24 cm in length, and no more than 15 cm is ever required for 2ST/2Gr. Thus, there is almost always a third (if not a fourth) limb of ST that would otherwise be discarded. Number 2 whipstitches are placed in each end of this extra graft limb. The whipstitches from one end are tied one to one around the fabric loop of the Endobutton loop (Fig. 17-1). The sutures from the other end are tied one to one around the tibial cortical screw. 118

FIG. 17-1 The fifth limb of the graft is shown as elevated above the remaining 2ST/2Gr graft. Whipstitches are tied around the Endobutton loop.

Results We recently presented an 8- to 9-year follow-up of a fivestrand technique using whipstitch post fixation on both the tibia and femur24 in 20 consecutive patients. This was the first report of a greater than four-strand HS graft using a single-bundle technique. No graft failures were found, and 89% of the grafts were within 1 mm of the opposite knee. The mean side-to-side KT-1000 difference of 0.44 mm is the lowest reported for an ST/Gr graft. We compared this group with a previously reported high-stability 2ST/2Gr cohort and found significantly higher stability with the five-strand graft.

Morbidity All patients regained full motion. There were no symptoms attributable to the greater size of the graft. Thus, we believe that this larger graft can safely be used without concerns for impingement if tunnels are properly placed.

Uses This technique is useful in patients with ligamentous laxity, small tendons, or other stability risk factors for which the strongest possible graft is required. It is also of use in double-bundle techniques. The 3ST part of the graft allows the AM bundle to approximate the strength of a 2ST/2Gr single bundle (210% versus 238% of the approximate strength of the native ACL by extrapolation from the data of Noyes25). Thus, the use of the Gr for the PL bundle does not need to significantly weaken the AM bundle, which closely corresponds to what most surgeons were using for a single bundle. This provides a measure of insurance in case the more difficult PL bundle is misplaced or inadequately

2ST/2Gr, 4ST, and 3ST/2Gr Techniques: Deciding Which Hamstring Configuration to Use tightened. Because double-bundle techniques are new to most surgeons, this should essentially eliminate any “learning curve” laxity as facility with the double-technique is gained and as further research shows the best ways to perform the double-bundle procedure.

FOUR-STRAND ST GRAFT PREPARATION TECHNIQUE 4ST with Bone Block See Chapter 16 for a description of this technique.

4ST Free Graft Without Bone Block This technique is similar to the 2ST/2Gr described previously. The two free ends of the graft are overlapped, and a whipstitch of #5 braided nonabsorbable suture is placed. Another whipstitch is then put into the apex of the graft as it is held taut with a #5 or #2 suture placed within the fold of the tendon while strong tension is exerted on the opposite free ends. The net result is a double-thickness graft, which can be fixated in an identical manner as the 2ST/2Gr graft.

CONCLUSIONS 1 There are five parameters for choosing a hamstring graft configuration: length for tunnel healing, length for fixation compatibility, whether or not the Gr is sacrificed, strength, and double-bundle compatibility. 2 2ST/2Gr is preferred to 4ST by most surgeons due to the greater available graft length. Some surgeons will use 4ST with 30 cm or longer ST harvests and 2ST/2Gr with shorter harvests. 3 4ST offers the advantage of not harvesting the Gr. 4 The 3ST/2Gr five-strand graft offers very high strength and more length than the 4ST. It is useful in patients with ligamentous laxity, small tendons, or other stability risk factors. 5 Regarding minimum graft tunnel length: 15 mm of graft would appear to be all that is necessary in the tunnels for adequate healing. Overly aggressive rehabilitation in the first 8 weeks should be avoided. 6 Gracilis harvest does not disable two hamstrings because the Gr is not a hamstring but rather is an adductor, both anatomically and functionally. It deactivates one accessory hamstring and one accessory adductor. In both cases,

17

function is well taken up by the prime movers in each group.

References 1. Prodromos CC, Joyce BT, Shi K, et al. A meta-analysis of stability after anterior cruciate ligament reconstruction as a function of hamstring versus patellar-tendon graft and fixation type. Arthroscopy 2005;21:1202–1208. 2. Cooley VJ, Deffner KT, Rosenberg TD. Quadrupled semitendinosus anterior cruciate ligament reconstruction: 5-year results in patients without meniscus loss. Arthroscopy 2001;17:795–800. 3. Gobbi A, Tuy B, Mahajan S, et al. Quadrupled bone-semitendinosus anterior cruciate ligament reconstruction: a clinical investigation in a group of athletes. Arthroscopy 2003;19:691–699. 4. Prodromos CC, Han YS, Keller BL, et al. Stability results of hamstring anterior cruciate ligament reconstruction at two- to eight-year follow-up. Arthroscopy 2005;21:138–146. 5. Feller JA, Webster KE. A randomized comparison of patellar tendon and hamstring tendon anterior cruciate ligament reconstruction. Am J Sports Med 2003;31:564–573. 6. Yasuda K, Kondo E, Ichiyama H, et al. Anatomic reconstruction of the anteromedial and posterolateral bundles of the anterior cruciate ligament using hamstring tendon grafts. Arthroscopy 2004;20: 1015–1025. 7. Gobbi A, Mahajan S, Zanazzo M, et al. Patellar tendon versus quadrupled bone-semitendinosus anterior cruciate ligament reconstruction: a prospective clinical investigation in athletes. Arthroscopy 2003;19:592–601. 8. Duthon VB, Barea C, Abrassart S, et al. Anatomy of the anterior cruciate ligament. Knee Surg Sports Traumatol Arthrosc 2006;14: 204–213. 9. Prodromos CC, Fu F, Howell S, et al. Controversies in soft tissue anterior cruciate ligament reconstruction. Presented at the 2006 Symposium of the American Academy of Orthopaedic Surgeons, AAOS Symposium—Controversies in Soft Tissue Reconstruction, Chicago, March, 2006. 10. Greis PE, Burks RT, Bachus K, et al. The influence of tendon length and fit on the strength of a tendon-bone tunnel complex: a biomechanical and histologic study in the dog. Am J Sports Med 2001;29:493–497. 11. Zantop T, Brucker P, Bell K, et al. The effect of tunnel-graft length on the primary and secondary stability in ACL reconstruction: a study in a goat model. Presented at the 2006 meeting of the European Society of Sports Traumatology, Knee Surgery, and Arthroscopy, Innsbruck, Australia, May, 2006. 12. Yamazaki S, Yasuda K, Tomita F, et al. The effect of intraosseous graft length on tendon-bone healing in anterior cruciate ligament reconstruction using flexor tendon. Knee Surg Sports Traumatol Arthrosc 2006;14:1086–1093. 13. Paulos L. Personal communication, May 2006. 14. Goss CM. Muscles and Fasciae. In Gray's anatomy, ed 29. Philadelphia, Lea and Febiger, Courage Books, 1973, pp 495–503. 15. Gobbi A, Domzalski M, Pascual J, et al. Hamstring anterior cruciate ligament reconstruction: is it necessary to sacrifice the gracilis? Arthroscopy 2005;21:275–280. 16. Noyes FR, Butler DL, Grood ES, et al. Biomechanical analysis of human ligament grafts used in knee-ligament repairs and reconstructions. J Bone Joint Surg Am 1984;66A:344–352. 17. Meyestre J, Vallotton J, Benvenuti J. Double semitendinosus anterior cruciate ligament reconstruction: 10-year results. Knee Surg Sports Traumatol Arthrosc 1998;6:76–81. 18. Aglietti P, Buzzi R, Menchetti P, et al. Arthroscopically assisted semitendinosus and gracilis tendon graft in reconstruction for acute

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19.

20.

21.

22.

120

anterior cruciate ligament injuries in athletes. Am J Sports Med 1996;24:726–731. Anderson A, Snyder R, Lipscomb B. Anterior cruciate ligament reconstruction: a prospective randomized study of three surgical methods. Am J Sports Med 2001;29:272–279. Goradia VK, Grana WA. A comparison of outcomes at 2 to 6 years after acute and chronic anterior cruciate ligament reconstructions using hamstring tendon grafts. Arthroscopy 2001;17:383–392. Harilainen A, Sandelin J, Jansson KA. Cross-pin femoral fixation versus metal interference screw fixation in anterior cruciate ligament reconstruction with hamstring tendons: results of a controlled prospective randomized study with 2-year follow-up. Arthroscopy 2005;21:25–33. Yasuda K, Kondo E, Ichiyama H, et al. Clinical evaluation of anatomic double-bundle anterior cruciate ligament reconstruction

procedure using hamstring tendon grafts: comparisons among three different procedures. Arthroscopy 2006;22:240–251. 23. Zhao J, Peng X, He Y, et al. Two-bundle anterior cruciate ligament reconstruction with eight-stranded hamstring tendons: four-tunnel technique. Knee 2006;13:36–41. 24. Prodromos CC, Joyce BT. Five-strand hamstring ACL reconstruction: a new technique with better long-term stability than four-strand. Presented at the 2006 meeting of the Arthroscopy Association of North America Hollywood, FL, May, 2006. 25. Noyes FR, Butler DL, Grood ES, Zernicke RF, Hefzy MS. Biomechanical analysis of human ligament grafts used in kneeligament repairs and reconstructions. J Bone Joint Surg Am 1984;66-A:344–352.

PART D PRINCIPLES OF TUNNEL FORMATION SUB PART I SINGLE FEMORAL-TUNNEL FORMATION

Use of the Transtibial Technique to Avoid Posterior Cruciate Ligament and Roof Impingement of an Anterior Cruciate Ligament Graft INTRODUCTION This chapter discusses the definition, complications, diagnosis, and prevention of posterior cruciate ligament (PCL) and roof impingement, which must be avoided to restore motion and stability in an anterior cruciate ligament (ACL) reconstructed knee. Evidence will be presented that the key tunnel in the transtibial technique is the tibial tunnel. Correct placement of the tibial tunnel in the coronal and sagittal planes, and subsequent drilling of the femoral tunnel through the tibial tunnel, avoids PCL and roof impingement, replicates the tension pattern of the intact ACL, and determines the motion and stability of the knee. The rationale for preventing PCL and roof impingement requires an understanding of the anatomy of the intercondylar notch, especially the wide variations in the cross-sectional relationship between the ACL graft, intact ACL, and PCL. A time-tested and scientifically evaluated surgical technique for placing the tibial and femoral tunnels that consistently prevents PCL and roof impingement is presented. This simple and accurate technique relies on widening the notch by performing a wallplasty and using a tibial guide that controls the angle of the tibial tunnel in the coronal plane and registers the intercondylar roof with the knee in extension in the sagittal plane. In the coronal plane, the tibial guide prevents PCL impingement by customizing the placement of the guidewire at 60 to 65 degrees with

respect to the medial joint line of the tibia and placing the lateral edge of the tibial tunnel through the tip of the lateral tibial spine. In the sagittal plane, the tibial guide prevents roof impingement by placing the guidewire 5 to 6 mm posterior and parallel to the intercondylar roof with the knee in maximal hyperextension.

18 CHAPTER

Stephen M. Howell

DEFINITION, COMPLICATIONS, AND DIAGNOSIS OF POSTERIOR CRUCIATE LIGAMENT IMPINGEMENT PCL impingement occurs when the ACL graft wraps around the PCL as the knee is flexed. Impingement of the ACL graft around the PCL causes a tension rise in flexion that either limits flexion or stretches the ACL graft, resulting in anterior instability. Not widening the notch and malplacement of the ACL graft in the coronal plane cause PCL impingement in the transtibial technique.1–3 PCL impingement can be suspected if bone was not removed from the lateral femoral condyle (i.e., a wallplasty) until the space between the PCL and lateral femoral condyle exceeded the width of the ACL graft by 1 mm. An anteroposterior (AP) radiograph is diagnostic of PCL impingement when the tibial tunnel is at an angle greater than 70 degrees with respect to the medial joint line or when the lateral edge of the tibial tunnel is medial to the apex of the lateral tibial spine2 (Fig. 18-1). Magnetic resonance imaging (MRI) with three-dimensional (3D)

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FIG. 18-1 The anterior cruciate ligament (ACL) grafts in both of these knees suffered from posterior cruciate ligament (PCL) impingement. The surgical error in the left radiograph was that the tibial tunnel was placed too vertical at 85 degrees, which placed the femoral tunnel at the apex of the notch. The tibial tunnel should have been placed at 65 degrees with respect to the medial joint line of the tibia. However, placing the tibial tunnel at 65 degrees does not guarantee that the ACL graft is placed without PCL impingement. The surgical error in the right radiograph is that the notch was not widened with a wallplasty, and the tibial tunnel and femoral tunnel were placed too medial, such that the femoral tunnel was at the apex of the notch. The lateral edge of the tibial tunnel should pass through the tip of the lateral spine, not through the tip of the medial spine.

reconstruction is diagnostic of PCL impingement when there is no space between the ACL graft and PCL or when the ACL graft does not run straight and is deformed by the PCL.1 Arthroscopy is diagnostic of PCL impingement when there is no space between the ACL graft and PCL at the apex of the notch and when the ACL graft is slack and bows laterally with the knee in 30 degrees of flexion.3 Surgeons who avoid PCL impingement will find that their patients have better knee flexion and better anterior and rotatory stability.1,2

DEFINITION, COMPLICATIONS, AND DIAGNOSIS OF ROOF IMPINGEMENT Roof impingement occurs when the intercondylar roof contacts the ACL graft before the knee reaches full extension. Impingement of the ACL graft against the intercondylar roof causes either a loss of extension or a stretching out of the graft from abrasion, resulting in anterior instability. The cause of roof impingement is malplacement of the ACL graft in the sagittal plane. Placing the tibial tunnel anterior to the intercondylar roof with the knee in maximal extension causes roof impingement.4–7 122

A lateral radiograph of the knee in maximal extension is diagnostic of roof impingement when the tibial tunnel is anterior to the intercondylar roof (Fig. 18-2). The lateral radiograph is less helpful in evaluating a bone–patellar tendon–bone graft than a soft tissue graft because the bone plug may obscure the wall and orientation of the tibial tunnel and because the tendon does not fill the bone tunnel.7 An MRI is diagnostic of roof impingement when the pathognomonic regionalized signal increase occurs in the graft, which is confined to the distal two-thirds of the ligament within the intercondylar notch. The portion of the ACL graft in the tibial and femoral tunnel and the portion of the graft that exits the femoral tunnel retain a low signal, which is identical to the PCL and patellar tendon.8–10 Arthroscopy is diagnostic of roof impingement when the ACL graft is frayed or a fibrous nodule is formed at the entrance of the tibial tunnel into the notch.11 Surgeons who avoid roof impingement will find that their patients have better knee extension and stability.7,12

THE TIBIAL TUNNEL: THE KEY TUNNEL IN THE TRANSTIBIAL TECHNIQUE The advantage of the transtibial technique is that when the notch is widened and the tibial tunnel is placed correctly in

Use of the Transtibial Technique to Avoid Posterior Cruciate Ligament and Roof Impingement of an Anterior Cruciate Ligament Graft

18

FIG. 18-2 The bone–patella–bone graft failed from roof impingement (left radiograph). The surgical error was that the tibial tunnel was placed anterior to the intercondylar roof with the knee in full extension. The graft failed due to abrasion and stretch-out. The tibial tunnel was moved more posterior in the revision with a hamstring anterior cruciate ligament (ACL) graft (right radiograph). The hamstring graft was pushed more posterior by a bone graft placed along the anterior edge of the tunnel (asterisk). The tibial tunnel should be placed posterior to the intercondylar roof with the knee in maximal extension.

the coronal and sagittal plane, the correct placement of the femoral tunnel is automatic. The reason for this is that the position of the over-the-top femoral aimer and the position of the reamer are both controlled by the tibial tunnel.3 If the notch is not widened and the tibial tunnel is placed incorrectly in either the coronal or sagittal plane, then the femoral tunnel will be placed incorrectly and the patient will suffer from motion loss or instability.1,2,7 The feasibility of the transtibial technique to replicate the tension pattern of the intact ACL was determined by a cadaveric study that analyzed the effect of varying the angle of the tibial tunnel (and femoral tunnel) in the coronal plane on the tension pattern of the ACL graft (Fig. 18-3). Drilling the tibial tunnel at an angle of 60 degrees in the coronal plane placed the ACL graft far down the side wall of the notch away from the PCL, and the tension in the graft matched the intact ACL. Drilling the tibial tunnel at 70 and 80 degrees placed the ACL graft near the apex of the notch and the PCL, and the tension increase in the ACL graft with knee flexion was subsequently abolished by incremental excision of 2 to 6 mm of the lateral edge of the PCL. Therefore, the cause of the abnormal tension rise in flexion is the premature mechanical impingement of the ACL graft on the PCL during flexion and is avoided by placing the tibial tunnel at an angle less than 70 degrees.3

RATIONALE FOR WIDENING THE NOTCH TO PREVENT POSTERIOR CRUCIATE LIGAMENT IMPINGEMENT The surgeon must recognize that a soft tissue ACL graft is bigger than the intact ACL. Women of the same height and weight as men have significantly narrower notches, which means that women require more of a wallplasty than males for the same-diameter graft.13 An MRI study of the cross-section of the intercondylar notch has shown that the intact ACL is thin and elongated and fits snugly between the lateral edge of the PCL and the medial edge of the lateral femoral condyle.1 The use of a soft tissue ACL graft that is rounder and larger in a cross-sectional area than the intact ACL requires widening the notch until the space between the lateral femoral condyle and PCL exceeds the width of the graft by 1 mm. Arthroscopy has shown that the portion of the notch occupied by the PCL and intact ACL varies widely. Most notches are “PCL dominant,” in which the PCL occupies a larger crosssectional area than the ACL (Fig. 18-4). Because surgeons prefer an ACL graft with a diameter of 8 to 10 mm, a wallplasty is required to make room for the larger ACL graft in almost every ACL reconstruction, especially in females. 123

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FIG. 18-3 The key tunnel in the transtibial technique is the tibial tunnel because the position of the over-the-top femoral aimer and the position of the reamer are both controlled by the tibial tunnel. When the tibial tunnel is drilled at 60 degrees with respect to the medial joint line, the femoral tunnel is placed farther down the side wall away from the posterior cruciate ligament (PCL), and the tension pattern in the graft is the same as the intact anterior cruciate ligament (ACL). When the tibial tunnel is drilled at 80 degrees, the femoral tunnel is placed near the apex of the notch adjacent to the PCL, and the tension pattern in the graft is abnormally increased at 60 degrees of knee flexion. The tension increase in flexion is caused by the graft impinging against the PCL, which either limits knee flexion or causes the graft to stretch, resulting in increased anterior laxity.

PRINCIPLE FOR AVOIDING POSTERIOR CRUCIATE LIGAMENT AND ROOF IMPINGEMENT The principle for avoiding PCL and roof impingement is to widen the notch and correctly place the tibial tunnel in the coronal and sagittal planes (Fig. 18-5). In the coronal plane, the angle of the tibial tunnel should be 60 to 65 degrees with respect to the medial joint line of the tibia, and the lateral edge of the tibial tunnel should pass through the tip of the

lateral spine.3 In the sagittal plane, the position of the tibial tunnel should be posterior and parallel to the intercondylar roof with the knee in extension, and the position should be customized based on variability in knee extension and roof angle so that a roofplasty is not required.6,14,15 Customized placement of the tibial tunnel in the sagittal plane is necessary because the sagittal depth of the insertion of the ACL is variable, the roof angle varies from 23 to 60 degrees, and knee extension varies from 5 to 15 degrees

FIG. 18-4 Notches come in many sizes and shapes; however, most notches are too narrow to hold an 8- to 10-mm round soft tissue anterior cruciate ligament (ACL) graft. The normal ACL is thin, spindle shaped, and much narrower than the cross-section of an 8- to 10-mm graft. Furthermore, the notch in females is narrower than in males, and many notches in both genders are posterior cruciate ligament (PCL) dominant, with more than half of the cross-section of the notch occupied by the PCL (left). Performing a wallplasty until the width between the lateral edge of the PCL and the lateral femoral condyle exceeds the width of the graft by 1 mm helps prevent PCL impingement. Widening the notch allows the tibial tunnel to be placed more lateral so that the lateral edge of the tibial tunnel passes through the tip of the lateral spine.

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18

FIG. 18-5 The optimal placement for the tibial tunnel in the coronal and sagittal planes is shown. The lateral edge of the tibial tunnel passes through the tip of the lateral tibial spine (asterisk), and the tibial tunnel forms an angle between 60 and 65 degrees with respect to the medial joint line in the coronal view (left). The tibial tunnel is posterior to the intercondylar roof with the knee in extension (right). This patient regained full flexion and extension and remained stable because the anterior cruciate ligament (ACL) graft was placed without posterior cruciate ligament (PCL) and roof impingement.

of hyperextension.14 The variability in the sagittal depth of the ACL insertion from 11 to 30 mm makes it a poor landmark for a point-and-shoot guide to select the position for an ACL graft with a diameter of 8, 9, or 10 mm.6 Customizing the placement of the tibial tunnel in the sagittal plane requires a tibial guide that registers the intercondylar roof with the knee in maximal hyperextension.16,17 The advantage of customizing the tibial tunnel is that roof impingement is avoided without a roofplasty, which has been shown to increase the graft tension at midrange of flexion and increase anterior laxity as the knee is flexed.15

SURGICAL TECHNIQUE FOR AVOIDING POSTERIOR CRUCIATE LIGAMENT AND ROOF IMPINGEMENT AND REPLICATING THE TENSION PATTERN OF THE INTACT ANTERIOR CRUCIATE LIGAMENT This surgical technique requires the use of a tibial guide that registers the intercondylar roof and a coronal alignment rod placed in the handle of the guide that allows the angle of the tibial tunnel in the coronal plane to be visually adjusted by the surgeon at the time of reconstruction (Howell 65 , Howell Tibial Guide, Arthrotek, Warsaw, IN)18 (Fig. 18-6). The use of a coronal alignment guide reduces the need for inoperative radiography to check the positioning of the tibial tunnel.

The initial arthroscopic examination of the notch should focus on removing the remnant of the torn ACL and clearly visualizing the lateral edge of the PCL. The tip of the guide, which is 9.5 mm wide, is passed between the PCL and the lateral femoral condyle. The knee is then gradually extended to examine whether enough space exists between the lateral femoral condyle and the PCL. The notch is then widened from its base to the apex until the 9.5-mm-wide tip of the guide easily passes between the lateral femoral condyle and the PCL (Fig. 18-7). A roofplasty is not performed. The tibial guide is then reinserted, and the knee is placed in full hyperextension (see Fig. 18-6). The heel of the patient’s leg is placed on the Mayo stand to maintain the knee in maximal hyperextension. The coronal alignment guide is inserted into the guide, the knee is brought into full hyperextension so that it is parallel to the roof, and the coronal alignment rod is adjusted so that it is parallel to the joint line and perpendicular to the tibia. The guidewire is drilled through the lateral hole in the bullet, which moves the guidewire laterally away from the PCL. The position of the guidewire is then checked arthroscopically. In the AP view the guidewire should enter midway between the lateral edge of the PCL and lateral femoral condyle. In full extension a probe can be placed between the anterior surface of the guidewire and the roof, and there should be 2 to 3 mm of clearance, which indicates that the guidewire is not placed too far posterior. 125

Anterior Cruciate Ligament Reconstruction

a

a

FIG. 18-6 The 65-degree Howell Tibial Guide simultaneously orients the tibial tunnel in both the sagittal and coronal planes. The guide is inserted into the notch, the knee is maximally extended, and the surgeon lifts the handle of the guide, which aligns the guidewire 6 mm posterior and parallel to the intercondylar roof. An alignment rod (a) is inserted into the handle of the guide, and the guide is rotated until the rod is parallel to the joint line and perpendicular to the long axis of the tibia, which sets the angle of the tibial tunnel in the coronal plane at 65 degrees. The guidewire is drilled through the lateral rather than the central hole in the bullet, which moves the tibial tunnel away from the lateral edge of the posterior cruciate ligament (PCL).

After drilling the tibial tunnel, an impingement rod is passed into the knee through the tibial tunnel with the knee in maximal hyperextension. Free passage of the impingement rod into the notch indicates no impingement of the ACL graft against the PCL, lateral femoral condyle, and intercondylar roof. A size-specific femoral aimer with an offset that produces a femoral tunnel with a 1-mm back wall is then inserted through the tibial tunnel. The tip of the femoral aimer is hooked proximal to the lateral wall of the notch and rotated slightly lateral away from the PCL. Once the graft is passed, a triangular space should be seen between the PCL and the ACL graft at the apex of the notch (Fig. 18-8).

VALIDATION OF TIBIAL GUIDE One advantage of drilling the tibial tunnel with the knee in full hyperextension using the 65-degree tibial guide is that no manipulation of the knee is required to reduce the knee and drill the guidewire anatomically. Simply extending the knee and placing the heel on the Mayo stand suspends the knee and allows gravity to reduce the tibia on the femur.17 The 65-degree tibial guide was shown to place the tibial tunnel on the posterior half of the ACL footprint and avoid roof impingement without a roofplasty in a cadaveric study of 21 knees.13 Mapping demonstrated a widevariety in width, depth, and shape of the footprint of the

FIG. 18-7 Most notches are too narrow to accommodate an 8- to 10-mm round soft tissue anterior cruciate ligament (ACL) graft. In this case, the notch is posterior cruciate ligament (PCL) dominant, with more than half of the cross-section of the notch being occupied by the PCL (left). A wallplasty is performed until the space between the PCL and lateral femoral condyle exceeds the width of the graft by 1 mm (center). The adequacy of the wallplasty is confirmed by free passage of the 9.5-mm-wide tip of the tibial guide between the PCL and lateral femoral condyle (right).

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18

FIG. 18-8 These arthroscopic views show what not to do and what to do to correctly place the tibial and femoral tunnel using the transtibial technique. The tibial guidewire should pass midway between the posterior cruciate ligament (PCL) and the lateral femoral condyle and not cross the PCL at the floor of the notch (left). The femoral tunnel ends up too vertical when the guidewire crosses the PCL at the floor of the notch, and there is no triangular space between the anterior cruciate ligament (ACL) graft and PCL at the apex of the notch, which is diagnostic of PCL impingement (center). The correctly placed tibial and femoral tunnel is more lateral to the PCL, and a relatively large triangular space exists at the apex of the notch between the ACL graft and PCL (right).

intact ACL insertion, which emphasizes the difficulty in selecting the location of the tibial tunnel with use of a point-and-shoot guide and using the ACL insertion as a target. The consistency of the relationship of the ACL to the intercondylar roof and the inconsistency of the footprint substantiate the principle of using a tibial guide that registers the intercondylar roof with the knee in full hyperextension to select the position of the tibial guidewire.19 The use of the coronal alignment guide is preferred over the use of a “clock” as a way of judging whether the femoral tunnel is placed correctly in the coronal plane. A simple experiment can be done to show how imprecise the use of the clock is in determining the location of the femoral tunnel in the coronal plane. With the femoral guidewire drilled through the tibial tunnel and into the notch, place the scope through the anterolateral or transpatellar porta, and rotate the 30-degree arthroscope and camera independently. The “time” formed by the guidewire and the margin of the intercondylar notch will vary by 2 hours. Repeat the experiment in the anteromedial portal, and observe how the maximal and minimal time differs from the view in the previous portal. Therefore, one surgeon’s two-o’clock position may be another surgeon’s one-o’clock position, depending on the choice of portal, rotation of the scope, and rotation of the camera.

SUMMARY Proper tunnel placement is essential for a successful ACL reconstruction. The complications that are caused by a poorly placed tibial tunnel in the coronal or sagittal plane cannot be overcome by the best graft material, fixation methods, or rehabilitation program. Correct tibial tunnel placement in the AP plane requires that the notch be

widened so that the space between the PCL and lateral femoral condyle exceeds the diameter of the graft by 1 mm, the tibial tunnel is placed such that the lateral edge passes through the tip of the lateral spine, and the angle formed by the tibial tunnel and the medial joint line and tibia is between 60 and 65 degrees. In the sagittal plane, the center of the tibial tunnel must be aligned 4 to 5 mm posterior to the intercondylar roof in the extended knee so that roof impingement is avoided without performing a roofplasty.

References 1. Fujimoto E, Sumen Y, Deie M, et al: Anterior cruciate ligament graft impingement against the posterior cruciate ligament: diagnosis using MRI plus three-dimensional reconstruction software. Magn Reson Imaging 2004;22:1125–1129. 2. Howell SM, Gittins ME, Gottlieb JE, et al: The relationship between the angle of the tibial tunnel in the coronal plane and loss of flexion and anterior laxity after anterior cruciate ligament reconstruction. Am J Sports Med 2001;29:567–574. 3. Simmons R, Howell SM, Hull ML: Effect of the angle of the femoral and tibial tunnels in the coronal plane and incremental excision of the posterior cruciate ligament on tension of an anterior cruciate ligament graft: an in vitro study. J Bone Joint Surg Am 2003;85A:1018–1029. 4. Goss BC, Howell SM, Hull ML: Quadriceps load aggravates and roofplasty mitigates active impingement of anterior cruciate ligament grafts against the intercondylar roof. J Orthop Res 1998;16:611–617. 5. Goss BC, Hull ML, Howell SM: Contact pressure and tension in anterior cruciate ligament grafts subjected to roof impingement during passive extension. J Orthop Res 1997;15:263–268. 6. Howell SM, Clark JA, Farley TE: A rationale for predicting anterior cruciate graft impingement by the intercondylar roof. A magnetic resonance imaging study. Am J Sports Med 1991;19:276–282. 7. Howell SM, Taylor MA: Failure of reconstruction of the anterior cruciate ligament due to impingement by the intercondylar roof. J Bone Joint Surg Am 1993;75:1044–1055. 8. Howell SM, Berns GS, Farley TE: Unimpinged and impinged anterior cruciate ligament grafts: MR signal intensity measurements. Radiology 1991;179:639–643. 9. Howell SM, Clark JA, Blasier RD: Serial magnetic resonance imaging of hamstring anterior cruciate ligament autografts during

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10.

11.

12.

13.

14.

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the first year of implantation. A preliminary study. Am J Sports Med 1991;19:42–47. Howell SM, Clark JA, Farley TE: Serial magnetic resonance study assessing the effects of impingement on the MR image of the patellar tendon graft. Arthroscopy 1992;8:350–358. Watanabe BM, Howell SM: Arthroscopic findings associated with roof impingement of an anterior cruciate ligament graft. Am J Sports Med 1995;23:616–625. Howell SM, Taylor MA: Brace-free rehabilitation, with early return to activity, for knees reconstructed with a double-looped semitendinosus and gracilis graft. J Bone Joint Surg Am 1996;78:814–825. Shelbourne KD, Kerr B: The relationship of femoral intercondylar notch width to height, weight, and sex in patients with intact anterior cruciate ligaments. Am J Knee Surg 2001;14:92–96. Howell SM, Barad SJ: Knee extension and its relationship to the slope of the intercondylar roof. Implications for positioning the tibial tunnel

15.

16.

17.

18. 19.

in anterior cruciate ligament reconstructions. Am J Sports Med 1995;23:288–294. Markolf KL, Hame SL, Hunter DM, et al: Biomechanical effects of femoral notchplasty in anterior cruciate ligament reconstruction. Am J Sports Med 2002;30:83–89. Howell SM: Principles for placing the tibial tunnel and avoiding roof impingement during reconstruction of a torn anterior cruciate ligament. Knee Surg Sports Traumatol Arthrosc 1998;6: S49–S55. Howell SM, Lawhorn KW: Gravity reduces the tibia when using a tibial guide that targets the intercondylar roof. Am J Sports Med 2004;32:1702–1710. www.drstevehowell.com/ezloc_video.cfm. Cuomo P, Edwards A, Giron F, et al: Validation of the 65 degrees Howell guide for anterior cruciate ligament reconstruction. Arthroscopy 2006;22:70–75.

The Anteromedial Portal for Anterior Cruciate Ligament Reconstruction INTRODUCTION The correct placement of the femoral tunnel is very essential for the success of the anterior cruciate ligament (ACL) reconstruction. The transtibial drilling of the femoral tunnel has been very much popularized because of its simplicity and good visualization. However, there is evi­ dence that drilling the femoral tunnel through the tibial tunnel can result in a nonanatomical placement of the graft in the femur.1 In the past, drilling the femoral tunnel more laterally at the medial surface of the lateral femoral condyle (LFC) (2 or 10 o’clock) has been proposed for better functional results, especially to avoid not only the anterior drawer but also the pathological rotation of the tibia.2–4 Recently it was shown the tension curve of grafts in the 9-o’clock position is similar to the characteristic pattern of the normal ACL’s tension curve.5 To reach this position (centered at 2 or 10 o’clock with the lowest point near 9 or 3 o’clock), the anteromedial portal is essential. Thus, the anteromedial portal has become more and more attractive lately, and a large num­ ber of orthopaedic surgeons prefer this portal.6–12

ADVANTAGES The advantages of this technique are as follows: 1 Easy manipulation of the instruments to drill the tunnel in any position at the medial side of the LFC without considering the placement of the tibial tunnel.

2 The femoral and tibial tunnels are drilled separately. Thus, one can choose the desired placement of the femoral tunnel without considering the placement of the tibial tunnel. 3 There is no risk of enlarging the tibial tunnel posteriorly, which can lead to poor fitting and stabilization of the graft in the tunnel.

19 CHAPTER

Manfred Bernard Stavros Ristanis Vassilis Chouliaras Hans Paessler Anastasios Georgoulis

4 By using bone–patellar tendon–bone (BPTB) graft, there is not any divergence when placing the interference screw. 5 In two-bundle ACL reconstruction, it is easier to choose the two entry points. 6 The drilling can be performed with the knee flexed to 120 degrees. In this position the 10-o’lock and also the 9-o’clock position can easily be reached without the risk of a blow­ out fracture of the dorsal corticalis of the femoral condyle. 7 The correct rotation of the graft insertion toward the long femur axis (important to restore the anteromedial and posterolateral bundle using BPTB graft) is easily found because it is parallel to the tibia plateau in the 120-degree flexion position.

TECHNIQUE The technique is as follows: 1 Place the anterolateral portal for the arthroscope 2 to 3 cm higher than the tibial plateau between the lateral distal border of 129

Anterior Cruciate Ligament Reconstruction the patella and the LFC. Place the anteromedial portal 1 cm higher than the tibial plateau and very close to the medial border of the patellar tendon. 2 Resect the ligamentum mucosum and, if needed, pieces of infrapatellar fat for better visualization. In 90 degrees of flexion, débride the posterior surface of the medial side of the LFC from soft tissues. The posterior margin of the notch must be clearly identified to ensure an over-the-top position. This identification is very important to place the femoral tunnel as far posteriorly as desired. Introduce a femoral guide (6 mm offset for an 8-mm hamstring graft or 7 mm offset for a 10-mm BPTB graft) through the medial portal. 3 Slowly flex the knee to 120 degrees, and check for good visualization. Sometimes, higher fluid pressure is demanded, or parts of the fat pad have to be removed to have good visualization of the femoral footprint of the ACL. The center of the femoral tunnel is the center of the ACL footprint at 10 o’clock in the left knee and 2 o’clock in the right knee. Drill a 2.5-mm guidewire through the LFC with the knee in 120 degrees of flexion; the drill exits from the skin at the lateral side of the femur. In this position (120 degrees of flexion), the drill should be aligned parallel to the tibial plateau. Thus, a dorsal blow-out fracture is surely avoided.

Change the drilling machine and fix it at that end of the wire that exits through the skin. Withdraw the Kirschner wire (K wire) until its inner end is flushed with the bone level of the LFC. Now the ending of the K wire marks the estimated center of ACL insertion (Fig. 19-1). Under fluoroscopic control in strictly lateral projection, superimpose both femoral condyles on the monitor. Measure the position of the end of the K wire using the quadrant method (Figs. 19-2 and 19-3).13 It is not necessary to perform an additional fluoroscopic tunnel view because the quadrant method determines the position of the end of the K wire in the anteroposterior direction as well (Fig. 19-4). Overdrill the K wire if its position is correct; if not, replace the K wire, and repeat the fluoroscopy. 6 Remove a small piece of the entry of the femoral tunnel, where the screw has to be inserted by BPTB graft.

4 If you are certain that the guidewire is in the correct position, overdrill the guidewire with a reamer in the chosen depth (8-mm diameter and 35-mm depth for a hamstring graft stabilized by Endobutton or 10-mm diameter and 25-mm depth for a BPTB graft).

7 Drill the tibial tunnel in 90 degrees of flexion. The entry point is selected close to the anterior border of the medial collateral ligament (MCL). The center of the tibial tunnel in the intraarticular space is slightly medial to the center of the intercondylar region on a line joining the inner edge of the anterior horn of the lateral meniscus and the medial tibial spine. With the knee joint in hyperextension and dorsal drawer position, we check that this point is at least 5 mm dorsal from the roof of the intercondylar notch to avoid an impingement of the graft.

5 If you are not sure about the correct position, the placement of the guidewire should be controlled fluoroscopically (recommended for all arthroscopic procedures) as follows:

8 Introduce the tibial guide, and insert a guidewire at an angle of 60 degrees to the tibial plateau. Overdrill the guide with the desired reamer, and check for possible impingement.

FIG. 19-1 Withdraw the K wire (A) until its end is flush with the wall of the lateral condyle (B).

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19

FIG. 19-3 Quadrant method: taking a strictly lateral radiograph, superimposing both condyles, quartering the sagittal diameter, and quartering the notch height. The center of the anterior cruciate ligament (ACL) insertion is located in the distal corner of the most superoposterior quadrant (arrow).

knee flexion. In this position the anatomy of

the anteromedial and posterolateral bundle is

reconstructed.

12 Performing the double-bundle technique; the line between both femoral drill holes should be parallel to the tibial plateau in 120 degrees of knee flexion to restore the correct course of the bundles. This orientation is only achieved using the anteromedial portal (Fig. 19-5). 13 Using the BPTB graft, insert a screw guide parallel to the bone plug through the small widening of the femoral tunnel. Flex the knee joint to 120 degrees, and insert the screw under visualization. FIG. 19-2 Fluoroscopic control in lateral projection (A). The end of the K wire (red circle) marks the estimated center of the insertion (B).

9 With eyelet K wire, pull a suture to the lateral side of the femur. Pull the suture from the tibial tunnel until the medial side of the tibia is reached. 10 Pull the graft to the desired position, using this suture. Sometimes it is necessary to extend or flex the knee joint to facilitate passing the graft through the tibial and femoral tunnels. 11 Using the BPTB graft, rotate the femoral bone block in the tunnel such that the anatomical angle between the long axis of the insertion area and the long axis of the femur is restored. This is reached by adjusting the corticalis of the bone block parallel to the tibial plateau in 120 degrees of

14 Fix the graft at the tibia in about 25 to 30 degrees of flexion.

POSSIBLE COMPLICATIONS Possible complications include the following: 1 Risk of breaking the posterior femoral cortex if the knee is not in 120 degrees of flexion. 2 Poor visualization by inserting an interference screw in 120 degrees of flexion. In this case, insert the screw in 90 degrees of flexion until the tip is at the femoral tunnel, and then bend the knee joint in 120 degrees of flexion, and insert the screw in this position.

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FIG. 19-4 Example of K wire positioning in true lateral projection (A) and in Frick’s projection (B). The yellow arrows demonstrate the correlation of the endings of the K wires (black points) in both projections if they are even with the bony surface of the condyle. The position in craniocaudal direction in the lateral view corresponds to the clockwise position in the tunnel view. For instance, a positioning at 25% of B (height of the notch) in the lateral view leads to the 1:30 clock position in the anteroposterior view (left knee). A drill hole that is positioned at 0% of B in the lateral projection would be in the high-noon position in Frick’s projection.

120˚

Axis femur

25˚

90˚

26˚

Axis tibia

5˚

A

B

FIG. 19-5 In 120 degrees of knee flexion, the corticalis of bone block should be adjusted toward and parallel to the tibial plateau. Because of the tibial slope, an angle of 25 degrees results between the long axis of the insertion area and the axis of the femur (A). This corresponds to the anatomical inclination angle of 26 degrees between both axes (B). Restoring this correct inclination angle is important to reconstruct the course of the anteromedial and posterolateral bundle. Similar conditions are valid when performing the double-bundle technique. In this case the line between both femoral drill holes should be parallel to the tibial plateau in 120 degrees of knee flexion. This orientation is only achieved using the anteromedial portal.

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References 1. Arnold MP, Kooloos J, van Kampen A. Single-incision technique misses the anatomical femoral anterior cruciate ligament insertion: a cadaver study. Knee Surg Sports Traumatol Arthrosc 2001;9:194–199. 2. Georgoulis A, Papadonikolakis A, Papageorgiou CD, et al. Threedimensional tibiofemoral kinematics of the anterior cruciate ligamentdeficient and reconstructed knee during walking. Am J Sports Med 2003;31:76–79. 3. Ristanis S, Giakas G, Papageorgiou CD, et al. The effects of anterior cruciate ligament reconstruction on tibial rotation during pivoting after descending stairs. Knee Surg Sports Traumatol Arthrosc 2003; 11:360–365. 4. Yagi M, Wong E, Kanamori A, et al. Biomechanical analysis of an anatomic anterior cruciate ligament reconstruction. Am J Sports Med 2002;30:660–666. 5. Arnold MP, Verdonschot N, van Kampen A. ACL graft can replicate the normal ligament’s tension curve. Knee Surg Sports Traumatol Arthrosc 2005;13:625–631. 6. Paessler HH. New techniques in knee surgery. Darmstadt, 2003. 7. Scranton PE, Pinczewski L, Auld MK, et al. Outpatient endoscopic quadruple hamstring anterior cruciate ligament reconstruction. Oper Tech Orthop 1996;6:177–180. 8. Giron F, Buzzi R, Aglietti P. Femoral tunnel position in anterior cru­ ciate ligament reconstruction using three techniques. A cadaver study. Arthroscopy 1999;15:750–756. 9. Hertel P, Behrend H, Cierpinski T, et al. ACL reconstruction using bone-patellar tendon-bone press-fit fixation: 10-year clinical results. Knee Surg Sports Traumatol Arthrosc 2005;13:248–255. 10. Chhabra A, Kline AJ, Nilles KM, Harner CD. Tunnel expansion after anterior cruciate ligament reconstruction with autogenous hamstrings: a comparison of the medial portal and transtibial techniques. Arthro­ scopy 2006;22:1107–1112.

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11. Bellier G, Christel P, Colombet P, et al. Double-stranded hamstring graft for anterior cruciate ligament reconstruction. Arthroscopy 2004; 20:890–894. 12. Morgan CD, Stein DA, Leitman EH, Kalman VR. Anatomic tibial graft fixation using a retrograde bio-interference screw for endoscopic anterior cruciate ligament reconstruction. Arthroscopy 2002;18(7):E38. 13. Bernard M, Hertel P, Hornung H, et al. Femoral insertion of the ACL. Radiographic quadrant method. Am J Knee Surg 1997;10:14–22.

Suggested Readings Galla M, Uffmann J, Lobenhoffer P. Femoral fixation of hamstring tendon autografts using the TransFix device with additional bone grafting in an anteromedial portal technique. Arch Orthop Trauma Surg 2004;124:281–284. Georgoulis AD, Papageorgiou CD, Makris CA, et al. Anterior cruciate lig­ ament reconstruction with the press-fit technique: 2–5 years follow-up of 42 patients. Acta Orthop Scand Suppl 1997;275:42–45. Georgoulis AD, Tokis A, Bernard M, et al. The anteromedial portal for drilling of the femoral tunnel for ACL reconstruction. Tech Orthop 2005;20:228–229. Gobbi A, Mahajan S, Tuy B, et al. Hamstring graft tibial fixation: bio­ mechanical properties of different linkage systems. Knee Surg Sports Traumatol Arthrosc 2002;10:330–334. Hantes ME, Dailiana Z, Zachos VC, et al. Anterior cruciate ligament reconstruction using the Bio-TransFix femoral fixation device and ante­ romedial portal technique. Knee Surg Sports Traumatol Arthrosc 2006;14:497–501. Lobenhoffer P, Bernard M, Agneskirchner J. Qualitätssicherung in der Kreuzbandchirurgie. Arthroskopie 2003;16:202–208. Pässler HH, Höher J. Intraoperative Qualitätskontrolle bei der Bohrkanalplat­ zierung zum vorderen Kreuzbandersatz Unfallchirurg 2004;107:263–272.

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Giancarlo Puddu Guglielmo Cerullo Massimo Cipolla Vittorio Franco Enrico Giannì

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The Retrodrill Technique for Anterior Cruciate Ligament Reconstruction INTRODUCTION Arthroscopic controlled retrograde drilling of femoral and tibial sockets and tunnels using a specially designed cannulated drill pin and retrocutter (Fig. 20-1) provides greater flexibility for anatomical graft placement and avoids previous tunnels and intraosseous hardware in revision cases. Inside-out drilling of femoral and tibial sockets minimizes incisions and eliminates intraarticular cortical bone fragmentation of tunnel rims common to conventional antegrade methods. This technique is also ideal for skeletally immature patients because drilling and graft fixation through growth plates may be avoided. Initial tunnel positioning (and not referencing) for cannulated drill guide pin placement is carried out from outsidein. This technique (outside-in/inside-out) combines the advantages of the two-incision and one-incision techniques. In fact, it permits surgeons, as with the two-incision technique, to drill a pin guide from outside to inside in order to obtain the correct anatomical insertion of the anterior cruciate ligament (ACL) (Fig. 20-2), which is otherwise not reproducible from inside-out. This technique permits the surgeon to prepare a femoral and a tibial socket or tunnel by initiating the socket drilling from the intraarticular surfaces in an inside-out method (Fig. 20-3). Since November 2004, our preferred technique for hamstring (autogenous quadrupled semitendinosus/gracilis) ACL reconstruction incorporates the just-mentioned femoral socket creation. In recent years, arthroscopically assisted

ACL reconstruction has become the procedure of choice. Initially, arthroscopic techniques required two incisions for outside-in drilling of bone tunnels, but there has been a trend toward using a single incision with inside-out drilling of the femoral tunnel. Those who advocate the twoincision technique state that they do so primarily because they believe that the two-incision procedure facilitates accurate femoral tunnel placement.1,2 Harner et al3 found no difference in tunnel placement using the two-incision technique, whereas Schiavone et al4 found that the femoral tunnels were significantly more vertical in the one-incision procedure. We have performed two-incision ACL reconstruction routinely since 1977 with very favorable results. The recent variation in our technique affords a reduction in morbidity associated with improved cosmesis and quicker postoperative recovery. A factor related to our success appears to be the result of a more anatomically positioned femoral tunnel, which in our hands is difficult to accomplish with single-incision transtibial femoral socket creation. Arnold et al,1 who examined the arthroscopic appearance of the ACL attachment in fresh frozen cadaver knees, found that the ligament consistently inserted on the lateral wall of the notch. No fibers were found to attach high in the roof. Furthermore, they found that the single-incision technique always missed the anatomical femoral ACL insertion. Another advantage of the retrodrill is that the traditional (outside-in) drilling methods disrupt the proximal tibial cortex with the drill penetration and

The Retrodrill Technique for Anterior Cruciate Ligament Reconstruction

20

FIG. 20-1 The 3-mm threaded cannulated drill pin with the retrodrill assembled.

FIG. 20-3 The retrodrill is assembled into the guide pin and begins to create the femoral socket.

FIG. 20-2 The pin is in the correct anatomical position in the notch.

may lead to tunnel widening. Retrodrilling produces a consistently smooth tibial and femoral intraarticular socket or tunnel entrance, maintaining the desired cortical integrity (Fig. 20-4). The retrodrill technique allows preparation of the correct anatomical femoral and tibial socket or tunnel with a very small lateral skin incision or without any skin incisions if the surgeon is using an allograft, and it appears to represent a promising futuristic technique in ACL reconstruction.

FEMORAL TUNNEL PLACEMENT Over the past several decades, bioengineers and orthopaedic surgeons have applied the principles of biomechanics to gain valuable information about the tunnel placement in ACL reconstruction and its relationship to knee stability. Still, both short- and long-term clinical outcomes studies have

FIG. 20-4 The traditional drilling method disrupts the proximal tibial cortex (A); the retrodrill technique produces consistently a smooth tibial entrance, maintaining the desired cortical integrity (B).

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Anterior Cruciate Ligament Reconstruction revealed that 11% to 32% of the patients experience unsatisfactory results after ACL reconstruction.5 The position of an ACL graft is the most critical surgical variable because it has a direct effect on knee biomechanics and, ultimately, on clinical outcome. Currently, limited data are available from prospective studies that identify the optimal intraarticular position of an ACL graft on the femur and tibia. A recent review of the literature by Beynnon et al6 shows that the center of the femoral attachment of an ACL graft should be located along a line parallel to the Blumensaat line, just posterior to the center of the normal ACL’s insertion to bone at either the 10-o’clock position (right knee) or the 2-o’clock position (left knee) when observed through the femoral notch. Graft placement, especially the tunnel on the femoral side, has long been a subject of debate. To date, most surgeons choose to place it in the footprint of the anteromedial bundle of the ACL (i.e., near the 11-o’clock position on the frontal view of the right knee). However, results of biomechanical and clinical research have suggested that it is necessary to place the tunnel more laterally for rotatory knee stability. Yamamoto et al5 compared a lateral and an anatomical tunnel placement using a robotic universal force sensor and concluded that a lateral tunnel placement can restore rotatory and anterior knee stability similarly to an anatomical reconstruction when the knee is near extension. Loh et al7 published a paper studying how well an ACL graft fixed at the 10- and 11-o’clock positions could restore knee function in response to both externally applied anterior tibial and combined rotatory loads by comparing the biomechanical results with each other and with the intact knee. They concluded that the 10-o’clock position more effectively resists rotatory loads when compared with the 11-o’clock position, as evidenced by smaller anterior tibial translation and higher in situ force in the graft. More recently Scopp et al8 performed a biomechanical study on 10 matched pairs of fresh frozen cadaver knees alternately assigned to a standard or an oblique tunnel position (at 10-o’clock) reconstruction. The investigators concluded that an ACL reconstruction using oblique femoral tunnels restored normal knee kinematics. In conclusion, it appears that actually there is a trend toward placing the femoral tunnel more laterally between the anteromedial and posterolateral anterior cruciate footprints (i.e., the 10-o’clock position). Biomechanics helped to clarify that although fixation at 11 o’clock is effective to resist an anterior tibial load, the more lateral 10-o’clock position could achieve better knee stability under rotatory loads (i.e., pivot shift). More recently, Arnold et al9 found that it is possible to replicate the characteristics of the tension curve of the normal ACL with a graft in a tunnel located at the 9-o’clock position.

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SURGICAL TECHNIQUE With the knee flexed at 90 degrees, after removing the remnants of the torn ACL, soft tissue and periosteum are débrided from the lateral wall of the notch. Additional bony notchplasty is performed as needed. The posterior margin of the notch is clearly identified. To locate the desired center of the femoral tunnel, we use a femoral guide recently made by Arthrex (Naples, FL) that keys off the over-the-top position. The guide enters the knee from the anteromedial portal and with its curved hook is fastened to the lateral femoral condyle in the over-the-top position at the 10:30 position for the right knee and the 1:30 position for the left knee. Our guide, with its variable hook, permits us to drill a specially designed cannulated guide pin from outside to inside that emerges in the lateral wall of the notch just 4 to 6 mm anterior to the posterior margin of the notch. When drilled, this creates a tunnel 7 to 10 mm in diameter, which leaves a 0.5- to 1-mm rim of posterior cortex. Reproducing this tunnel with the exact location in the frontal, sagittal, and coronal planes with a guidewire drilled from inside-out is quite impossible, especially if done through a predrilled tibial tunnel. With the guide positioned in the notch, a mini (2-cm) lateral skin and fascia incision is carried out corresponding with the tip of the guide, and the drill sleeve is advanced to the femoral cortex along the lateral aspect of the knee (Fig. 20-5). A cannulated threaded pin (3 mm in diameter) is drilled through the drill sleeve and the femoral condyle until it enters intraarticularly, as observed with the arthroscope (see Fig. 20-2). The correct location is confirmed. Then a mini retrograde cutting drill (retrocutter) (Arthrex) 7 to 10 mm in diameter (depending on the width of the graft that has been previously harvested and measured)

FIG. 20-5 Via the placement of a special femoral guide, a cannulated pin is inserted from outside into the femoral notch.

The Retrodrill Technique for Anterior Cruciate Ligament Reconstruction is introduced in the knee from the anteromedial portal already preloaded on a reverse-threaded instrument. As threads of the guide pin engage the retrocutter, the reverse threads of the drill holder facilitate simultaneous disengagement of the retrocutter from the instrument (Fig. 20-6, A ). A handle is set up on the outer end of the pin to permit the manual advancement of the inner end of the pin onto the retrocutter. The cannulated pin is also calibrated in order to easily know the lateral condyle width. Then a socket of 2.5 to 3.5 cm is retrodrilled, pulling the drill from outside (Fig. 20-6, B), leaving 1 cm of intact bone. The retrodrill is then gently pushed back in the joint. Once the retrocutter engages its holder, the drill is reversed; reverse drilling securely engages the retrocutter on the holder and simultaneously disengages the retrocutter from the threaded guide pin. A shaver is used to remove any debris in the joint and to chamfer the tunnels edges, and a suture (#2 FiberStik, Arthrex) is introduced in the joint through the cannulated pin for graft passing. A tibial tunnel of the same diameter is prepared in a routine manner, or a tibial socket can be made in the same way as the femoral (Fig. 20-7) if so planned by the surgeon. The suture is pulled out from the tibial tunnel. The graft (quadruple gracilis and semitendinosus) is marked to locate the exact portion that has to fill the femoral tunnel and is prepared with two #5 Fiberwire (Arthrex) sutures at the femoral end and passed in the knee from the tibial to the

20

femoral tunnel. The fixation sutures exiting the lateral cortex of the femur are passed through a four-hole metal button and tied securely to fix the graft on the femur (Fig. 20-8). Either square or sliding knots can be used for this kind of suspension fixation. The tibial fixation is carried out in a routine way using an interference metal screw coupled with a staple or, more recently, with Fiberwire whipstitches interwoven in the graft and tied around a screw.

PRELIMINARY RESULTS AND CONCLUSIONS Our 70 cases performed from November 2004 to November 2005 (2 to 14 months of follow-up) do not permit a longterm evaluation. No intraoperative complications occurred when performing the retrodrill technique. In three cases the drill was not perfectly engaged in the pin, so we had to retrieve the drill from the joint with a grasper and reposition it onto the cannulated pin. There were no postoperative complications, and the early results evaluated with the International Knee Documentation Committee (IKDC) scoring system are very good. The retrodrill technique seems to be safe and effective for femoral socket preparation, as it is very likely to be for the tibial socket, representing the initial step for a completely “all inside” arthroscopic ACL reconstruction.

FIG. 20-6 The femoral cannulated guide pin engages the retrodrill and simultaneously disengages it from the holding instrument (A); the femoral socket is created by pulling distally, and retrograde drilling is completed to the socket depth planned by the surgeon (B). (Reprinted with permission from Arthrex, Inc., Naples, FL.)

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Anterior Cruciate Ligament Reconstruction

FIG. 20-7 The 3-mm cannulated drill guide pin is drilled through the tibia and the retrodrill is assembled (A); the tibial socket or tunnel is created, pulling the retrodrill to the depth planned by the surgeon (B). (Reprinted with permission from Arthrex, Inc., Naples, FL.)

References

FIG. 20-8 The button is inserted through the lateral femoral incision, and with two limbs of #5 reinforced suture (Fiberwire, Arthrex), the graft is fixed to the femur.

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1. Arnold MP, Kooloos J, van Kampen A. Single incision technique misses the anatomical femoral anterior cruciate ligament insertion: a cadaver study. Knee Surg Sports Traumatol Arthrosc 2001;9:194–199. 2. Khon D, Busche T, Carls J. Drill hole position in endoscopic anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthroscop 1998;6:S13–S15. 3. Harner C, Marks P, Fu F, et al. Anterior cruciate ligament reconstruction: endoscopic versus two incision technique. Arthroscopy 1994; 10:502–512. 4. Panni AS, Milano G, Tartarone M, et al. Clinical and radiographic results of ACL reconstruction: a 5- to 7-year follow-up study of outside-in versus inside-out reconstruction technique. Knee Surg Sports Traumatol Arthrosc 2001;22:77–85. 5. Yamamoto Y, Hsu WH, Woo SL-Y, et al. Knee stability and graft function after anterior cruciate ligament reconstruction: a comparison of a lateral and an anatomical femoral tunnel placement. Am J Sports Med 2004;32:1825–1832. 6. Beynnon BD, Johnson RJ, Abate J, et al. Treatment of anterior cruciate ligament injuries, part II. Am J Sports Med 2005;33:1751–1767. 7. Loh JC, Fukuda Y, Tsuda E, et al. Knee stability and graft function following anterior cruciate ligament reconstruction: comparison between 11 o’clock and 10 o’clock femoral tunnel placement. Arthroscopy 2003;19:297–304.

The Retrodrill Technique for Anterior Cruciate Ligament Reconstruction 8. Scopp JM, Jasper LE, Belkoff SM, et al. The effect of oblique femoral tunnel placement on rotational constraint of the knee reconstructed using patellar tendon autografts. Arthroscopy 2004;20:294–299. 9. Arnold MP, Verdonschot N, Van Kampen A. ACL graft can replicate the normal ligament’s tension curve. Knee Surg Sports Traumatol Arthrosc 2005;13:625–631.

Suggested Readings Andersen H, Dyhre-Poulsen P. The anterior cruciate ligament does play a role in controlling axial rotation in the knee. Knee Sur Sports Traumatol Arthrosc 1997;5:145–149.

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Beynnon BD, Johnson RJ, Abate JA, et al. Treatment of anterior cruciate ligament injuries, part I. Am J Sports Med 2005;33:1579–1602. Markolf KL, Hame S, Hunter DM, et al. Effects of femoral tunnel placement on knee laxity and forces in an anterior cruciate ligament graft. J Orthop Res 2000;20:1016–1024. Puddu G, Cerullo G. My technique in femoral tunnel preparation: the retrodrill technique. Tech Orthop 2005;20:224–227. Ristanis S, Stergiou N, Patras K, et al. Excessive tibial rotation during high-demand activities is not restored by anterior cruciate ligament reconstruction. Arthroscopy 2005;1:1323–1329. Sommer C, Friederich NF, Muller W. Improperly placed anterior cruciate ligament grafts: correlation between radiological parameters and clinical results. Knee Surg Sports Traumatol Arthrosc 2000;8:207–213.

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Femoral Tunnel Placement to Restore Normal Knee Laxity After Anterior Cruciate Ligament Reconstruction

Andrew A. Amis*

INTRODUCTION

CHAPTER

In order to perform a successful anterior cruciate ligament (ACL) reconstruction, the surgeon must make a number of steps that require correct judgment and execution, but there is evidence that the most frequent cause of failure is malpositioning of the graft tunnel in the femur.1 This is not surprising because of the anatomy of the interior of the knee joint and the difficulty of seeing the femoral attachment of the ACL. Because the surgeon views the interior of the intercondylar notch when the knee is flexed, the ACL attachment is carried back into the furthest recess of the knee. This means that there is plenty of scope to err with the tunnel placement if the ACL attachment is not visualized clearly. In particular, the undulating surface of the femoral intercondylar notch includes a transverse ridge or bulge that should come between the observer and the proximal part of the ACL attachment; the inexperienced surgeon may believe that this ridge is the posterior outlet of the notch and then place the graft tunnel shallow to that ridge in a nonanatomical position. The frequency of this error has led to common usage of the term “resident’s ridge” to describe this anatomical feature. The aim of this chapter is to describe the evolution of knowledge regarding ACL graft placement on the femur, which relates closely to our understanding of the function of the ACL *The author thanks all the surgeons engaged in ACL surgical research who have generously shared their expertise with him recently in his travels around the world, which were undertaken with the generous support of the BREG-ACL Study Group International Research Professorship.

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itself. There has been a recent move toward “anatomical” reconstructions, with two grafts in parallel, attempting to reproduce two functional fiber bundles of the ACL. This has prompted a better appreciation of the natural ACL attachment anatomy when performing a conventional single-bundle reconstruction. The tibial attachment is not considered here because changes of the femoral attachment have a much larger effect on ACL graft tension and length changes.2 In this chapter, two distinct sets of terminology will be used to describe femoral graft tunnel positions: (1) anatomical nomenclature for describing positions when the knee is in extension (anterior-posterior, proximal-distal) and (2) surgical nomenclature for describing what the surgeon views when the knee is flexed approximately 90 degrees (high-low, deep-shallow, respectively).3

FUNCTIONAL ANATOMY OF THE ANTERIOR CRUCIATE LIGAMENT RELATED TO GRAFT TUNNELS The ACL has a complex fiber structure composed of many fascicles bound together within a synovial covering layer. The fibers are not arranged simply in parallel, and this gives rise to the cross-sectional area being less at the midlength than at the bony attachments: the fibers must splay out toward the bones.4 The functional significance of this architecture is not understood. However, at a gross level, the fibers of the ACL are arranged as a flat band, and all are

Femoral Tunnel Placement to Restore Normal Knee Laxity After Anterior Cruciate Ligament Reconstruction tensed when the knee is extended (Fig. 21-1, A ). This fiber band is oriented in a sagittal plane so that the ACL fits into and fills the narrow slot between the posterior cruciate ligament (PCL), which occupies most of the width of the intercondylar notch, and the lateral femoral condyle. The sagittal plane of the ACL orientation means that it attaches to the tibia over an area that is oriented anteroposterior (AP). The ACL attaches to the femur over an area that is oriented from anteroproximal to posterodistal.5 This femoral attachment is close to and bounded posteriorly by the condylar articular cartilage and has an overall alignment approximately 35 degrees posterior-distal to the axial.6 When the knee flexes, the axis of rotation moves within the distal femur and the kinematics are affected by the loads

21

imposed on the knee, but the overall effect in the intact knee is that the most anterior fibers of the ACL remain close to a constant length and thus are often described as being “isometric.” Meanwhile, the more posterior the fibers, the more they slacken as the knee flexes, up to 90 degrees flexion2,7–10 (Fig. 21-1, B). These length change patterns have been measured in a number of studies,2,7,11 and it is generally accepted that an “isometry map” can be derived from such measurements.2,9,10 A modern surgical navigation system can produce such maps in response to the surgeon moving the knee during ACL reconstruction procedures, giving a patient-specific feedback on the likely length changes associated with choices of graft tunnel positions around the intercondylar notch12 (Fig. 21-2).

ANTERIOR CRUCIATE LIGAMENT ISOMETRY AND RECONSTRUCTION AMB tight

PLB tight

A

AMB tight

PLB slack in flexion

B FIG. 21-1 A, The anterior cruciate ligament (ACL) is arranged to form a parallel-fibered, ribbon-like structure when the knee is extended; the fibers are tensed in both the anteromedial bundle (AMB) and posterolateral bundle (PLB). B, When the knee flexes, the PLB slackens and its femoral attachment passes between the tight AMB and the wall of the notch; this causes the ACL to twist with knee flexion.

The observation that the anterior fibers of the ACL remained tight across the range of knee flexion, whereas the more posterior parts slackened, led to the belief that the anterior fibers were the most important. This was reinforced by the finding that the more anterior fibers had a greater material failure strength,13 which suggests that they have adapted to a more mechanically demanding role. A similar finding has been made for the PCL.14 These findings have been correlated with a higher collagen density in the anterior fiber bundles of both the ACL and PCL.15 A more practical reason to place a graft isometrically is that this implies the graft will not be subjected to cyclical length changes when the knee is moving, thus helping to protect it from fatigue or loosening effects. For example, O’Meara et al16 reported that isometric grafts survived cyclical motion in a continuous passive motion machine, whereas nonisometric grafts did not. The problem with this line of reasoning is that isometry measurements depend on the ACL being intact; otherwise the kinematics may be abnormal. Even when the ACL is intact, the isometric area on the femoral condyle is influenced sensitively by the loads imposed on the knee while it is being moved. This was shown by Zavras et al,17 who published a map showing a range of different recommended isometric graft locations from the previous literature (Fig. 21-3). Their reproduction of the published works confirmed that isometric behavior could be found reliably for attachment points only at the extreme anteroproximal corner of the natural ACL attachment area.2,9 This means that “isometric” ACL reconstructions are nonanatomical, with the femoral graft tunnel centered higher and deeper in the notch (with the knee flexed) than the natural attachment area. Despite this, the mainstream of opinion through the 1990s favored femoral graft tunnels placed isometrically. 141

Anterior Cruciate Ligament Reconstruction A

L

M

P

M

Although many clinical papers were published to report a high percentage of good and excellent results, there remained a high level of interest in ACL research and development, reflecting an underlying dissatisfaction with clinical outcome and a desire to find ways of improvement. One of the underlying principles that emerged from the isometry research studies was that there is a transition line between attachments that causes graft tightening or slackening with knee flexion.2 The transition line passes through the isometric point at the anteroproximal edge of the ACL attachment and from there runs distal and slightly posterior.2,8,9 Attachments anterior to the transition line lead to graft tightening with knee flexion, whereas grafts posterior to the transition line slacken (Fig. 21-4). At present, the principal method for objective assessment of the restoration of normal mechanics to the knee after ACL reconstruction is the measurement of tibiofemoral anterior translation laxity; that is, how far anteriorly the tibia moves in response to a known displacing force at

142

L

FIG. 21-2 A map of fiber attachment length changes produced during anterior cruciate ligament (ACL) reconstruction surgery by a navigation system. The “contour lines” represent areas with a given length change measured over a range of knee flexion. They converge toward a central zone of minimal length change. (With thanks for permission to Dr. Philippe Colombet, Merignac, France.)

a given angle of knee flexion. Very little work has been done to examine how well different ACL graft positions can restore anterior laxity to normal across the range of knee flexion. Even an incorrect graft placement might restore anterior drawer to normal at one angle of knee flexion (by adjusting the tension appropriately), but then it might behave abnormally and either overconstrain or allow excessive laxity as the knee moves away from the posture where the graft had been tensed. A study of alternative graft attachments investigated the effect of moving to different attachment points either at or around the isometric area on the femur.18 The in vitro study used artificial grafts secured into a barrel that was centered at the femoral isometric point (which had been ascertained by isometry measurements while the ACL was intact). Five attachment points were investigated: isometric, then anteroproximal, anterodistal, posteroproximal, or posterodistal to the isometric point, as shown in Fig. 21-5. It was found to be possible to restore tibiofemoral anterior

Femoral Tunnel Placement to Restore Normal Knee Laxity After Anterior Cruciate Ligament Reconstruction

S1

F

21

H Isometric drill hole

AM P

F

26

PP Superior

T

An

18

AA

P

B

Central Inferior

15

Original ACL Proposed insertions

L

11 24

5 mm

FIG. 21-3 Published isometric graft attachment sites: S1, Sidles et al10; F, Friederich and O’Brien9; H, Hefzy et al2; L, Cazenave and Laboureau31; B, Blankevoort et al32; An (anatomic), Odensten and Gillquist.33 (Reproduced from Zavras TD, Race A, Bull AMJ, et al. A comparative study of isometric points for ACL reconstruction. Knee Surg Sports Traumatol Arthrosc 2001;9:28–33, with kind permission of Springer Science and Business Media.)

pp ap

pd ad

FIG. 21-4 The transition line between graft attachments, which leads to graft tightening or slackening, passes posterodistally from the isometric area. Anterior attachments cause tightening, and posterior attachments cause slackening as the knee flexes.

FIG. 21-5 The five anterior cruciate ligament (ACL) graft attachment points investigated by Zavras et al.17 The central isometric point and the more posterior points lead to restoration of normal anterior laxity across the range of knee flexion; the posterodistal point is close to the center of the anatomical ACL attachment area. ad, Anterodistal; ap, anteroproximal; pd, posterodistal; pp, posteroproximal. (Reproduced from Zavras TD, Race A, Bull AMJ, et al. A comparative study of isometric points for ACL reconstruction. Knee Surg Sports Traumatol Arthrosc 2001;9:28-33, with kind permission of Springer Science and Business Media.)

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Anterior Cruciate Ligament Reconstruction laxity close to normal across the range of knee flexion investigated, with attachments that were either on that transition line or just posterior to it.18 The tendency of anterior femoral attachments to move away from the matching tibial attachment, and therefore cause the graft to tighten with knee flexion, led to overconstraint of the flexed knee; this was accompanied by elevated graft tension as the knee flexed. Grafts placed distal and posterior to the isometric point, which meant that they were in the anatomical ACL attachment, restored anterior laxity to that of the intact knee across the range of knee flexion investigated.

ANATOMICAL SINGLE-BUNDLE ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION The trend from isometric toward anatomical graft placement was encouraged by growing evidence of limitations with isometric grafts. In particular, their placement high in the notch meant that they were close to the center of the knee, which is not efficient if they are supposed to limit tibial rotational laxity. There has been a growing awareness that restoration of physiological anterior laxity, as measured routinely by a KT-1000 or similar device, is not sufficient to define a return to the knee working normally and that tibial rotational laxity is also important. The drawback of grafts placed high in the notch has been demonstrated in vivo after ACL reconstruction: one study found that the majority of knees with a patellar tendon ACL reconstruction had traces of residual rotational laxities during pivot-shift testing (a mini-pivot remained).19,20 Other studies have found that the limb with a reconstructed ACL had a persistence of abnormal tibial rotation during gait analysis.21,22 In addition, Amis and Dawkins7 cut the fiber bundles sequentially and measured the reduction in force needed to induce a given tibial anterior translation. The reduction in force needed to displace the tibia indicated the contribution that the cut fiber bundle had made to resisting tibial anterior drawer. It was found that the anteromedial fiber bundle was dominant in the flexed knee, as expected, knowing that the rest of the ACL was then slackened (see Fig. 21-1, B). Conversely, the posterolateral fiber bundle was dominant when the knee was near extension. This, of course, is the posture in which knee stability is most important, when standing. Such observations have led to a trend toward more anatomical graft placement. In single-bundle ACL reconstruction, that means that the tunnel should be placed at the center of the ACL attachment, which is distal and posterior to the isometric point. During surgery, with the knee flexed, this translates into a tunnel that is lower on the lateral side wall of the notch and also more shallow toward the surgeon compared with the isometric point. In practice, this translates 144

into continuing to use a fixed offset from the posterior outlet but bringing the guide around from approximately the 11-o’clock or 11:30 position to approximately the 10-o’clock position in a right knee. If there is any doubt about the accuracy of finding this point, in a chronic case in which the ACL remnants have disappeared, a guidewire may be placed and checked radiographically using the quadrant method of Bernard et al,23 who documented the center of the femoral ACL attachment. A method to navigate to this point3 is shown in Fig. 21-6. Studies on cadaveric knees24,25 have found that the anatomical tunnel placement (at the 10 o’clock position) led to better control of tibial rotation than did a tunnel placed higher in the notch (at the 11 o’clock position).

ANATOMICAL DOUBLE-BUNDLE ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION Recently there has been increasing interest in attempting to more closely achieve an anatomical reconstruction using a double-bundle graft. Although some studies have used double grafts passing to or from single tunnels in either the tibia or femur, it is usually accepted that an anatomical reconstruction has two grafts in parallel when the knee is extended, with two tunnels in each of the tibia and femur. The femoral ACL attachment has been split into the two bundle areas in Fig. 21-7.

High

0%

Shallow

Deep 28%

100% 100%

25%

Low

FIG. 21-6 The center of the femoral attachment of the anterior cruciate ligament (ACL) can be found by navigation in percentage terms from the over-the-top position in deep–shallow and high–low directions in the flexed knee.3 Bernard et al23 found the center of the ACL attachment to be 25% more shallow and 28% lower from the over-the-top position.

Femoral Tunnel Placement to Restore Normal Knee Laxity After Anterior Cruciate Ligament Reconstruction

21

AM

AMB PLB

AC

PL

PCL

FIG. 21-7 The femoral anterior cruciate ligament (ACL) attachment with the areas of the anteromedial (AMB) and posterolateral (PLB) fiber bundles.

If the knee is viewed arthroscopically, the anatomical ACL attachment area may be visualized via an anteromedial portal; the viewpoint across the notch gives a better appreciation of depth than can be gained when looking along the lateral side wall from an anterolateral portal.26 The differences in the double-bundle attachment sites, compared with the conventional tunnel high and deep in the notch, then become apparent. The tunnel for the anteromedial graft will still be close to the posterior outlet of the notch but will now be brought down to approximately the 10:30 position. Because of the sloping orientation of the posterior outlet of the notch, moving to the lateral wall also takes the graft tunnel toward the surgeon, which is more shallow (more distal). The tunnel for the posterolateral graft is farther distal and posterior anatomically, which means that it is lower on the side wall of the notch and much more shallow than the first tunnel (Fig. 21-8). Typical positions will be at the 9-o’clock orientation, with an offset sufficient to maintain a bone bridge between the tunnel mouths. With autogenous hamstring tendon grafts, the tunnels are typically 6 mm in diameter, and an offset of 8 mm between the tunnel centers maintains a bone bridge and matches the spacing of the natural fiber bundle attachments. This position will be much closer to the surgeon than with a conventional reconstruction and should also be low enough that the posterior edge of the tunnel is close to the articular cartilage margin at the place where it is closest to the tibia6 (see Fig. 21-8). Various instruments are being developed to allow the second (posterolateral) tunnel to be located relatively easily at a fixed offset distance from the first (anteromedial) tunnel,27 which can itself be located using a conventional offset drill guide hooked over the posterior rim of the intercondylar notch.

FIG. 21-8 The typical positions of double tunnels in a right knee flexed 90 degrees, viewed from an anteromedial portal. Note how the anteromedial bundle tunnel (AM) is close to the over-the-back position (asterisk) and that the posterolateral bundle tunnel (PL) is shallow (distal) and low (posterior) compared with the AM tunnel. Interrupted line, Approximate boundary of ACL attachment; AC, articular cartilage; PCL, posterior cruciate ligament. (Illustration provided kindly by Dr. F. Giron, Prima Clinica Ortopedica, Florence, Italy.)

DISCUSSION This chapter has outlined some of the thinking and research behind the recent evolution of femoral ACL graft tunnel placement. At one period the predominant doctrine was that the tunnel placement should produce isometric graft behavior, but that resulted in the tunnel being placed high in the notch, which was not anatomical. The mainstream of opinion has more recently moved toward an acceptance of anatomical graft placement, a philosophy to which some surgeons have always adhered. However, until recently there has been little interest in making a comparison between these approaches. Biomechanical researchers have produced evidence in vitro to support a move toward placing the ACL graft more anatomically, which is onto the lateral side wall of the intercondylar notch, at approximately 10 o’clock, and more shallow compared with the conventional isometric placements. A more recent development is the anatomical double-bundle reconstruction,28,29 but at present there is no reliable clinical evidence to support a change from a single-bundle ACL reconstruction.30

References 1. Getelman MH, Friedman MJ. Revision anterior cruciate ligament surgery. J Am Acad Orthop Surg 1999;7:189–198.

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Anterior Cruciate Ligament Reconstruction 2. Hefzy MS, Grood ES, Noyes FR. Factors affecting the region of most isometric femoral attachments. Part II: the anterior cruciate ligament. Am J Sports Med 1989;17:208–216. 3. Amis AA, Beynnon B, Blankevoort L, et al. Proceedings of the ESSKA scientific workshop on reconstruction of the anterior and posterior cruciate ligaments. Knee Surg Sports Traumatol Arthrosc 1994;2:124–132. 4. Harner CD, Baek GH, Vogrin TM, et al. Quantitative analysis of human cruciate ligament insertions. Arthroscopy 1999;15:741–749. 5. Giron F, Cuomo P, Aglietti P, et al. Femoral attachment of the anterior cruciate ligament. Knee Surg Sports Traumatol Arthrosc 2006;14:250–256. 6. Yasuda K, Kondo E, Ichiyama H, et al. Anatomic reconstruction of the anteromedial and posterolateral bundles of the anterior cruciate ligament using hamstring tendon. Arthroscopy 2004;20:1015–1025. 7. Amis AA, Dawkins GPC. Functional anatomy of the anterior cruciate ligament—fibre bundle actions related to ligament replacements and injuries. J Bone Joint Surg 1991;73B:260–267. 8. Amis AA, Zavras TD. Review article: isometricity and graft placement during anterior cruciate ligament reconstruction. Knee 1995;2:5–17. 9. Friederich NF, O’Brien WR. Functional anatomy of the cruciate ligaments. In Jakob RP, Staubli HU (eds): The knee and the cruciate ligaments. Berlin, 1992, Springer Verlag, pp 78–91. 10. Sidles JA, Larson RV, Garbini JL, et al. Ligament length relationships in the moving knee. J Orthop Res 1988;6:583–610. 11. Sapega AA, Moyer RA, Schneck C, et al. Testing for isometry during reconstruction of the anterior cruciate ligament. J Bone Joint Surg 1990;72A:259–267. 12. Colombet P. Personal communication December, 2005. 13. Butler DL, Guan Y, Kay MD, et al. Location-dependent variations in the material properties of the anterior cruciate ligament. J Biomech 1992;25:511–518. 14. Race A, Amis AA. The mechanical properties of the two bundles of the human posterior cruciate ligament. J Biomech 1994;27:13–24. 15. Mommersteeg TJ, Blankevoort L, Kooloos JG, et al. Nonuniform distribution of collagen density in human knee ligaments. J Orthop Res 1994;12:238–245. 16. O’Meara PM, O’Brien WR, Henning CE. Anterior cruciate ligament reconstruction stability with continuous passive motion. Clin Orthop 1992;277:201–209. 17. Zavras TD, Race A, Bull AMJ, et al. A comparative study of isometric points for ACL reconstruction. Knee Surg Sports Traumatol Arthrosc 2001;9:28–33. 18. Zavras TD, Race A, Amis AA. The effect of femoral attachment location on anterior cruciate ligament reconstruction: graft tension patterns and restoration of normal anterior-posterior laxity patterns. Knee Surg Sports Traumatol Arthrosc 2005;13:92–100.

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19. Amis AA, Bull AMJ, Lie DTT. Biomechanics of rotational instability and anatomic anterior cruciate ligament reconstruction. Op Tech Orthop 2005;15:29–35. 20. Bull AMJ, Earnshaw PH, Smith A, et al. Intraoperative measurement of knee kinematics in reconstruction of the anterior cruciate ligament. J Bone Joint Surg 2002;84B:1075–1081. 21. Ristanis S, Giakas G, Papageorgiou CD, et al. The effects of anterior cruciate ligament reconstruction on tibial rotation during pivoting after descending stairs. Knee Surg Sports Traumatol Arthrosc 2003;11:360–365. 22. Tashman S, Collon D, Anderson K, et al. Abnormal rotational knee motion during running after anterior cruciate ligament reconstruction. Am J Sports Med 2004;32:975–983. 23. Bernard M, Hertel P, Hornung H, et al. Femoral insertion of the ACL. Radiographic quadrant method. Am J Knee Surg 1997;10:14–21. 24. Loh JC, Fukuda Y, Tsuda E, et al. Knee stability and graft function following anterior cruciate ligament reconstruction: comparison between 11 o’clock and 10 o’clock femoral tunnel placement. Arthroscopy 2003;19:297–304. 25. Scopp JM, Jasper JE, Belkoff SM, et al. The effect of oblique femoral tunnel placement on rotational contraint of the knee reconstructed using patellar tendon autografts. Arthroscopy 2004;20:294–299. 26. Fu F. Personal communication August, 2005. 27. Christel P, et al. Personal communication April, 2005. 28. Radford WJP, Amis AA. Biomechanics of a double prosthetic ligament in the anterior cruciate deficient knee. J Bone Joint Surg 1990;73B:1038–1043. 29. Yagi M, Wong EK, Kanamori A, et al. Biomechanical analysis of an anatomic anterior cruciate ligament reconstruction. Am J Sports Med 2002;30:660–666. 30. Adachi N, Ochi M, Uchio Y, et al. Reconstruction of the anterior cruciate ligament: single versus double-bundle multistranded hamstring tendons. J Bone Joint Surg 2004;86B:515–520. 31. Cazenave A, Laboureau JP: Isometric reconstruction of the anterior cruciate ligament. Pre- and peri-operative determination of the femoral isometric point. French J Orthop Surg 1990;4:255–259. 32. Blankevoort L, Huiskes R, van Kampen A. ACL reconstruction: simply a matter of isometry? In: Passive motion characteristics of the human knee joint—experiments and computer simulations. PhD thesis, University of Nijmegen, 1991, 151–162. 33. Odensten M, Gillquist J. Functional anatomy of the anterior cruciate ligament and a rationale for its reconstruction. J Bone Joint Surg 1985;67A:257–262.

SUB PART II DOUBLE ANTEROMEDIAL AND POSTEROLATERAL FEMORAL-

TUNNEL FORMATION

Anatomical Double-Bundle Anterior Cruciate Ligament Reconstruction Procedure Using the Semitendinosus and Gracilis Tendons INTRODUCTION The anterior cruciate ligament (ACL) is composed of the anteromedial bundle (AMB) and the posterolateral bundle (PLB), each with a different function.1–3 Since 2000, the author has reported the surgical principle4 and the latest procedure5 for an anatomical doublebundle ACL reconstruction that is intended to anatomically reconstruct the AMB and the PLB. In addition, the author’s team reported a prospective cohort study to evaluate this anatomical double-bundle procedure in comparison with single-bundle and nonanatomical double-bundle ACL reconstruction procedures using hamstring tendon grafts.6 Our procedure has several noteworthy characteristics. First, all four ends of two tendon grafts are grafted at the center of the anatomical attachment of the AMB or the PLB, not only on the femur but also on the tibia. Second, we use the transtibial tunnel technique to create femoral tunnels. Third, we use the hamstring tendonhybrid graft,7,8 in which the femoral end is connected with an Endobutton CL and the tibial end is connected with a polyester tape. Fourth, we fix the polyester tape portion of the graft onto the tibia with two staples at 10 degrees of knee flexion, simultaneously applying a 30N load to each graft. In this chapter, the surgical principle and the procedure of our anatomical double-bundle ACL reconstruction are explained.

PROCEDURE

22 CHAPTER

Kazunori Yasuda

Preparation for Arthroscopic Surgery Surgery is performed with an air tourniquet in the standard supine position. An approximately 3-cm-long oblique incision is made in the anteromedial portion of the proximal tibia. The semitendinosus and gracilis tendons are harvested using a tendon stripper in the figure-four knee position. When the semitendinosus tendon is thick and long enough, the gracilis tendon is not harvested. At the beginning of arthroscopic surgery, a surgeon sits beside the knee joint of the patient. An edge of a drape is attached to a lumbar portion of the surgeon so that the patient’s leg hanging beside the table can be put on the surgeon’s knee in a sterile condition. This setup allows the surgeon to control the patient’s knee position using the surgeon’s own knee. An arthroscope is inserted through the lateral infrapatellar portal. After a routine arthroscopic examination, a remnant of the torn ACL is resected, leaving 1-mm-long ligament tissue at the femoral and tibial insertions, which can be used as landmarks for inserting guidewires.

Creation of Tibial Tunnels In ACL reconstruction procedures with the transtibial tunnel technique, the greatest key to success is to create a tibial tunnel with an

147

Anterior Cruciate Ligament Reconstruction

D TP

* A

C

B

B appropriate three-dimensional (3D) direction. In other words, a tibial tunnel should be created so that a guidewire for femoral tunnel creation can be easily inserted at a targeted point on the lateral condyle through the tibial tunnel. To create such a tibial tunnel, we use a specially designed wire guide, called a wire navigator (Fig. 22-1, A), which was developed in our previous study.7,8 This device is composed of a navi-tip and a wire sleeve. The navi-tip consists of sharp tibial and femoral indicators. The axis of the wire sleeve passes through the tip of the tibial indicator (Fig. 22-1, B). First, a tibial tunnel for the PLB is created. The navi-tip is introduced into the joint cavity through 148

FIG. 22-1 The wire navigator (A) and the concept of wire navigation for the tibia (B). The wire navigator is composed of a navi-tip (A) and a wire sleeve (B). The navi-tip consists of the tibial indicator (C) and femoral indicator (D). The axis of the wire sleeve is passed through the tip of the tibial indicator. Keeping the tibial indicator at the targeted point on the tibia, we aim the femoral indicator at the targeted point (TP) on the femur. Subsequently, the direction and the insertion point of the wire are automatically determined.

the medial infrapatellar portal. The surgeon holds the tibia at 90 degrees of knee flexion, keeping the femur horizontal. The tibial indicator of the navi-tip is placed at the center of the PLB footprint on the tibia, which is located at the most posterior aspect of the area between the tibial eminences and 5 mm anterior to the posterior cruciate ligament (Fig. 22-2). Keeping the tibial indicator on this point, we aim the femoral indicator at the center of the PLB footprint on the femur (Fig. 22-3, A), which is precisely explained in the next section, and the proximal end of the extraarticularly located wire sleeve is fixed on the anteromedial aspect of the tibia through the skin incision made

Anatomical Double-Bundle Anterior Cruciate Ligament Reconstruction Procedure Using the Semitendinosus and Gracilis Tendons

FIG. 22-2 Two tibial tunnel outlets are shown. They are created at the center of the normal attachment of the anteromedial bundle (AMB) and posterolateral bundle (PLB).

for the graft harvest. The proximal end and the direction of the wire sleeve are automatically determined depending on the direction of the intraarticular navi-tip (see Fig. 22-1, B). A Kirschner wire of 2 mm in diameter is drilled through the sleeve in the tibia. According to our basic studies, this tunnel does not injure this ligament because the insertion point of the wire on the anteromedial aspect of the tibia is located several millimeters anterior to the medial collateral ligament.4 The first tunnel is made with an approximately 6-mm cannulated drill corresponding to the measured diameter of the prepared substitute.

22

Next, a Kirschner wire for the AMB reconstruction is drilled using the same wire navigator. The tibial indicator is placed at the center of the tibial footprint of the AMB, which is located at a point approximately 7 mm anterior to the center of the first tunnel (see Fig. 22-2). Keeping the tibial indicator on this point, we then aim the femoral indicator at the center of the femoral footprint of the AMB (Fig. 22-3, B). The wire sleeve is fixed on the anteromedial cortex of the tibia. A Kirschner wire is then drilled through the sleeve in the tibia. The knee should be extended to ensure that the tip of the second wire is located at a point 5 mm posterior to the anterior edge of the roof in the intercondylar notch. The second tunnel is drilled with an approximately 7-mm cannulated drill corresponding to the measured diameter of the prepared substitute. Subsequently, two intraarticular outlets are aligned in the sagittal plane (see Fig. 22-2).

Creation of Femoral Tunnels In the anatomical double-bundle procedure, it is essential to precisely understand the attachment of the main ACL fibers that should be reconstructed in ACL reconstruction. Although the normal ACL has a wide footprint on the lateral condyle,9–11 the author has found that the main ACL fiber attachment that should be reconstructed in ACL reconstruction is in the form of an egg, with its long axis inclined toward the posterior direction by 30 degrees

FIG. 22-3 The navi-tip of the wire navigator in an arthroscopic visual field. First (A), keeping the tibial indicator at the center of the posterolateral bundle (PLB) footprint on the tibia, a surgeon aims the femoral indicator at the center of the PLB footprint on the femur. Then (B), keeping the tibial indicator at the center of the anteromedial bundle (AMB) footprint on the tibia, a surgeon aims the femoral indicator at the center of the AMB footprint on the femur.

149

Anterior Cruciate Ligament Reconstruction to the long axis of the femur on the medial surface of the lateral femoral condyle4 (Fig. 22-4). First, a Kirschner wire is drilled at the center of the femoral footprint of the AMB through the second tibial tunnel, using the offset guide system (Transtibial Femoral ACL Drill Guide, Arthrex, Naples, FL). This point is located at the point 5 to 6 mm distal from the back of the femur (see Fig. 22-4). This point is consistent with the 1:30 (or 10:30) orientation for the left (or right) knee. Using this wire as a guide, a tunnel is made with a 4.5-mm cannulated drill. The length of the tunnel is measured with a scaled probe. Then, to precisely observe the lateral condyle in the arthroscopic visual field, the portal for the arthroscope is changed to the medial infrapatellar one. We have developed a reproducible method to identify the targeted point in the arthroscopic visual field.4 When the surgeon holds the tibia at 90 degrees of knee flexion, keeping the femur horizontal, we can draw an imaginary vertical line through the contact point between the femoral condyle and the tibial plateau in the arthroscopic visual field (see Fig. 22-4). The center of the attachment of the PLB is located approximately at the crossing point between the vertical line and the long axis of the ACL attachment. Therefore, when the remnant of the ACL is observed on the lateral condyle, this point can be easily determined. If the remnant of the ACL is not identified on the lateral condyle, the center of the attachment of the PLB can be determined as the point 5 to 8 mm anterior to the edge of the joint cartilage on

FIG. 22-4 Attachment of the anterior cruciate ligament (ACL) on the femur. The dotted lines show the attachment of the main fibers of the ACL. When we drew a vertical line (VL) through the contact point (C) between the femoral condyle and the tibial plateau on a picture taken at 90 degrees of flexion, this line and the long axis of the ACL attachment (AX) was crossed at the point (PL) on the vertical line 5 to 8 mm anterior to the edge of the joint cartilage. The center (AM) of the attachment of the anteromedial bundle was located at the point 5 to 6 mm distal from the back of the femur as measured using the offset guide. AFS, A parallel line with an axis of the femoral shaft.

150

the imaginary vertical line (see Fig. 22-4). The femoral tunnel that has been created already for the AMB reconstruction can be used as a good landmark to determine the center of the attachment of the PLB. To insert a guidewire at this point, the surgeon manually holds a Kirschner wire and aims it at the center of the attachment of the PLB on the femur through the tibial tunnel, keeping the femur horizontal at 90 degrees of knee flexion. Then the surgeon lightly hammers the wire into this point and drills it (Fig. 22-5, A). A 4.5-mm diameter tunnel is drilled using this wire as a guide. Our cadaveric study showed that this technique provides some benefits for Endobutton fixation, including easy passage of the graft and easy flip of an Endobutton.4 The tunnel length is measured in the same manner. Finally, two sockets are created for the AMB and PLB reconstruction with cannulated drills in the Endobutton fixation system (Acufex Microsurgical, Mansfield, MA), the diameter of which is matched to the two grafts prepared with the technique described in the following section. Thus, two tunnels are created inside the ACL remnant on the lateral condyle (Fig. 22-5, B). The different directions of the two pairs of tunnels are demonstrated by inserting two wires through the tibial tunnel to the femoral tunnel at 90 degrees of knee flexion (Fig. 22-5, C).

Graft Fashioning The harvested semitendinosus is cut in half. Regarding the gracilis tendon, both ends are resected so that the thickest portion is used for the graft, and the length is matched to half the length of the semitendinosus tendon. One-half of the semitendinosus tendon and the resected gracilis tendon are doubled and used for AMB reconstruction. The remaining half of the semitendinosus tendon is also doubled and used for the PLB reconstruction. Using these tendon materials, the hybrid grafts are fashioned (Fig. 22-6). At the looped end of each doubled tendon graft, an EndobuttonCL (Acufex Microsurgical, Mansfield, MA) is attached. The length of the Endobutton-CL is determined such that a 15- to 20-mm long tendon portion can be placed within the bone tunnel. A commercially available polyester tape (Leeds-Keio Artificial Ligament, Neoligament, Leeds, United Kingdom) is mechanically connected in series with the other end of the doubled tendons, using the original technique5 (see Fig. 22-6). This tape is strong, soft, meshed, 10 mm wide, and 15 cm long. In our experience, the diameter of the tendon portion ranges from 6 to 8 mm for the AMB graft and from 5 to 6 mm for the PLB graft. The first advantage of the hybrid graft is that it is stronger and stiffer than the tendon-suture composite.12,13 The second advantage is that the tape portions of the two grafts can be simultaneously fixed to the tibia with an initial tension.

Anatomical Double-Bundle Anterior Cruciate Ligament Reconstruction Procedure Using the Semitendinosus and Gracilis Tendons

22

FIG. 22-5 Insertion of a guidewire for the posterolateral bundle (PLB) into the femur using the transtibial tunnel technique (observed through the medial portal). A, First, a surgeon drills a Kirschner wire into the center of the PLB attachment on the femur. B, Two tunnels are independently created within the anterior cruciate ligament (ACL) remnant on the lateral condyle. C, Each wire is inserted through a tibial tunnel to a femoral tunnel at 90 degrees of knee flexion demonstrates the position and direction of a pair of tunnels. Note that the directions of the anteromedial bundle (A) and PLB (P) wires are different.

The latter feature is specifically important for anatomical double-bundle reconstruction.

Graft Placement The graft for the PLB reconstruction is introduced through the tibial tunnel to the femoral tunnel using a passing pin

and is fixed on the femur by an Endobutton. Then the graft for the AMB is placed in the same manner. Thus, the two bundles having different directions are intraarticularly grafted (Fig. 22-7). The grafts rarely impinge to the femur. Notchplasty is performed only in knees with an extremely narrow notch due to osteochondral spar formation or a similar problem. 151

Anterior Cruciate Ligament Reconstruction

FIG. 22-6 The hybrid grafts. At the looped end of each doubled tendon graft, an Endobutton-CL is attached. A polyester tape is mechanically connected in series with the other end of the doubled tendons, using the original technique. An absorbable suture marker is attached to each graft to show the point of flip of the Endobutton. The diameter of this tendon portion shows 7 to 8 mm for the anteromedial bundle (AMB) graft and 5 to 6 mm for the posterolateral bundle (PLB) graft.

FIG. 22-7 The reconstructed two bundles as observed through the lateral portal. The posterolateral bundle (P) is observed behind the anteromedial bundle (A).

Graft Tensioning and Fixation For graft fixation, the knee is flexed to 10 degrees with a sterilized thin pillow placed beneath the thigh, keeping the heel in contact with the operating table (Fig. 22-8). A spring tensiometer (Meira, Nagoya, Japan) is attached at each end of the polyester tape portion of the graft. An assistant surgeon simultaneously applies tension of 30N to each graft for 2 minutes at 10 degrees of knee flexion, and a surgeon simultaneously secures the two tape portions onto the anteromedial aspect of the tibia using two spiked staples in the turn-buckle fashion.5 152

FIG. 22-8 A surgeon simultaneously secures the two tape portions onto the anteromedial aspect of the tibia using two spiked staples, applying a 30N tension to each graft for 2 minutes using tensiometers (TM) at 10 degrees of knee flexion.

The mechanism of our tensioning technique is explained as follows14: According to our in vivo measurement studies, when we applied the same initial tension on each bundle at 10 degrees of knee flexion, each tension pattern was similar to that of the normal bundle. This fact suggested that the slight flexion position (10 degrees of knee flexion) is recommended as the most appropriate knee flexion angle for easy graft tensioning. On the other hand, the full extension position may be clinically recommended to avoid flexion contracture of the knee after surgery. However, our previous studies13,15 showed that the initial graft tension in the hamstring tendon graft was dramatically reduced in the early phase after surgery. Therefore, the slight flexion position is again recommended as the most appropriate knee flexion angle for graft tensioning, when we take into account the postoperative graft relaxation. Another important question about graft tensioning is whether we should separately fix the two grafts at different flexion angles. According to our in vivo measurement studies, if we apply a tension to the AMB after fixing the PLB at the extension position, the initial tension applied to the PLB is reduced to an unknown degree. A surgeon cannot sufficiently control the graft tension in this technique. Therefore, in anatomical double-bundle ACL reconstruction, it is important to simultaneously fix the two bundles, applying appropriate initial tensions to the two grafts. Postoperative 3D computed tomography shows that each tunnel outlet was created at the center of the anatomical attachment of the AMB or the PLB (Fig. 22-9).

CLINICAL RESULTS A prospective comparative cohort study was carried out with 72 consecutive patients with chronic ACL deficiency to compare three ACL reconstruction procedures using

Anatomical Double-Bundle Anterior Cruciate Ligament Reconstruction Procedure Using the Semitendinosus and Gracilis Tendons

22

FIG. 22-9 Postoperative three-dimensional computed tomography showing that each tunnel outlet was created at the center of the anatomical attachment of the anteromedial bundle (A) or the posterolateral bundle (P).

hamstring tendon grafts.6 The first 24 patients underwent a single-bundle procedure using a six-strand hamstring tendon graft. The next 24 patients underwent a nonanatomical double-bundle procedure using four-strand and two-strand hamstring tendon grafts. The final 24 patients underwent the anatomical double-bundle procedure using the same four-strand and two-strand hamstring tendon grafts. All 72 patients underwent postoperative management with the same rehabilitation protocol.6 There were no significant differences among the background factors. The postoperative anterior laxity measured with the KT-2000 was significantly less after the anatomical double-bundle reconstruction than after the single-bundle reconstruction. Concerning the results of the pivot-shift test, the anatomical double-bundle reconstruction was significantly better than the singlebundle reconstruction, although this test was not an objective evaluation (Table 22-1). In the International Knee Documentation Committee (IKDC) evaluation, the anatomical double-bundle reconstruction clinically tended to be superior to the single-bundle reconstruction, although no statistical significance could be calculated. There were no significant differences in the range of knee motion and the muscle torque. Thus, this study demonstrated that the anatomical double-bundle ACL reconstruction with the hamstring tendons was clinically useful in the treatment for the ACL deficient knee. In addition, this study also showed that in ACL reconstruction with the hamstring tendons, the anatomical double-bundle procedure was superior to the single-bundle procedure, at least in terms of restoration of the anterior and rotational knee stability as measured with the KT-2000 and pivot-shift examinations. We should consider reasons why the results concerning knee stability are superior in the anatomical double-bundle reconstruction in our clinical study compared

with the single-bundle reconstruction. Yagi et al16 reported that anatomical double-bundle reconstruction restores knee kinematics closer to normal than does single-bundle reconstruction. Namely, under a 134N anterior tibial load, anterior tibial translation for the anatomical reconstruction was significantly similar to that of the intact knee than was the single-bundle reconstruction. The in situ force in the ACL reconstructed with the anatomical double-bundle procedure averaged 97% of that in the normal ACL, whereas the force in the ACL reconstructed with the single-bundle procedure averaged only 89%. Therefore we can make the following speculations: First, the reconstructed PLB as well as the reconstructed AMB may be effective to reduce the anterior translation of the tibia in the range of less than 30 degrees. Second, excessively overloading to one bundle can be avoided during the remodeling phase, resulting in good maturation of not only the PLB graft but also the AMB graft. The good maturation of the AMB graft might result in the reduction of the anterior tibial translation at 90 degrees as well as 30 degrees. Third, the graft surface area of the two thin tendon grafts used in the anatomical procedure was greater than the area of the one thick graft used in the single-bundle procedure. Therefore, concerning graft anchoring and revascularization, the two thin bundles in the double-bundle reconstruction may be superior to the one thick bundle in the single-bundle reconstruction, resulting in the reduction of the anterior tibial translation at 30 and 90 degrees of knee flexion. Thus, there is a high possibility that the anatomical double-bundle ACL reconstruction with the hamstring tendons is clinically useful in the treatment for the ACL deficient knee. However, there are some limitations in our clinical study.6 To establish the clinical utility of the anatomical double-bundle ACL reconstruction for the ACL deficient knee, further clinical studies are needed concerning the 153

Anterior Cruciate Ligament Reconstruction TABLE 22-1 Clinical Results in the Postoperative Evaluation Single Bundle

Nonanatomical

Anatomical

Double Bundle

Double Bundle

Loss of knee

1 patient

2 patients

1 patient

0

0

1

(
)

12 patients

16 patients

21 patients

(þ)

9 patients

5 patients

3 patients

(þþ)

3 patients

3 patients

0 patients

2.8  1.9

2.2  1.5

1.1  0.9

5 mm

2 patients

3 patients

0 patients

flexion (5

6–7

>7 Fixation–

Pop.

Fixation–

Tib

Fem

0

Sc-WS

EB

HAMSTRING GROUPS EB2–4HS: Endobutton used on femur, second -generation fixation used on tibia (Subgroup 1) Cooley*

2001

4ST

20

100

0

Eriksson

2001

4ST

74

43

50

7

Sc-WS

EB

Feller*

2003

4STG

27

85

15

0

Sc-WS

EB

Gobbi*

July

4ST

40

90

8

2

Fastlok

EB

4ST

80

90

9

1

Fastlok

EB

Sc-WS

EB

ST-Buckle

EB

2003 Gobbi*

Sept 2003

Prodromos*

2005

4STG

98

86

Yasuda*

2004

4STG

57

80

396

80

Weighted mean (Subgroup 1)

97

14

14

14

3

3

3

0

14

0 0

0

0

1.7

OC-4HS: Other cortical 4HS (XP-4HSþSC -4HSþBu-4HS) (Subgroup 2)

Aglietti

2004

4STG

60

67

43

0

WL

BMS

Howell*

1999

4STG

67

91

6

3

2ST or LW

BMS

Harilainen

2005

4STG

25

72

8

20

Sc-LW

Transfx

Fabbriciani

2005

4STG

18

61

28

0

ISþST

Transfix

STþSc-WS

Sc-Lp

Weighted mean (Subgroup 3)

72

73

4.1

Sc-4HS: cortical screw on tibia and femur (Subgroup 4) Aglietti

Feb

4STG

30

23

47

30

1997

or Sc-WS

Goradia*

2001

3STG

93

90

Howell

1999

4STG

41

90

9

1 3

1

Sc-LW

Sc-LW

7

Sc-Lp

2 Sc-LWs (continued)

Stability Results After Anterior Cruciate Ligament Reconstruction

XP-4HS: Cross-pin femoral fixation (Subgroup 3)

69

541

542 Author

Year

Graft

KT


2


2x
3 >2 3–4

3–5 >3 4

4–5

>4 >5

Pop. Weighted mean (Subgroup 4)

6–7

>7 Fixation– Tib

78

Fixation– Fem

7.8

Bu-4HS: simple button on tibia and/or femur (Subgroup 5) Hamada*

2000

4STG

86

81

94

3

5

2

0

Bu or Sc-WS Bu or Sc-WS

Maeda

1996

4STG

41

63

73

17

10

Bu or Sc-WS Bu or Sc-WS

Noojin

2000

4ST

65

71

83

Williams

2004

4STG

79

71

82

Weighted mean (Subgroup 5)

73

85

Weighted mean (OC-4HS with extrapolation)

74

11 12

6

Bu or Sc-WS EB

6

St or IS or Bu EB

4.7 5.4

(Subgroup 2) Weighted mean (OC-4HS without extrapolation)

72

(Subgroup 2) AIS-4HS: Augmented interference screw fixation: 2IS plus augmentation Hill*

2005

4STG

21

86

14

0

ISþSt

IS

Charilton

2003

4STG

36

72

17

11

IS

IS

Harilainen

2005

3ST/4STG

29

62

21

17

IS

IS

Hill

2005

4STG

27

74

26

0

IS

IS

Scranton*

2002

4STG

120

88

3

IS

IS

Shaieb

2002

4STG

22

45

41

14

IS

IS

Wagner

2005

4STG

55

69

31

0

IS

IS

2IS-4HS: Double interference screw used (Subgroup 6)

9

Weighted mean (Subgroup 6)

75

5.4

WEIGHTED MEAN (All 4HS with extrapolation)

76.3

4.2

WEIGHTED MEAN (All 4HS without extrapolation)

77.2

4.2

2HS

Anterior Cruciate Ligament Reconstruction

TABLE 69-1—Clinical Series Divided by Graft and Fixation Method (Cont’d)

Author

Year

Graft

KT


2


2x
3 >2 3–4

3–5 >3 4

4–5

>4 >5

6–7

>7 Fixation–

Pop. 66

39

Fem

NI

St-Buckle

Aglietti

1996

2STG

62

50

Anderson

2001

2STG

34

62

38

NI

St

Anderson

2001

2STG

33

62

48

NI

NI

Beynnon

2002

2STG

22

St

ST-Buckle

Feagin

1997

2ST

91

17

Sc-LW

BB

Meyestre

1998

2ST

27

18

BB

Sc-LW or

45

26

11

Fixation–

Tib

55

56

Clip O’Neill

1996

2STG

40

75

Nebelung

1998

2ST

29

55

WEIGHTED MEAN (all 2HS)

83

18

10

35

54

7

St

St

10

St-Buckle

EB

13

BTB GROUPS 2IS BTB: two interference screws used; both tibia and femur (Subgroup 7) 2004

BTB

60

65

35

0

IS

IS

Arciero

1996

BTB

51

73

20

7

IS

IS

Arciero

1996

BTB

31

65

25

9

IS

IS

Bach

1995

BTB

62

90

5

5

IS

IS

Bach

1998

BTB

100

83

14

3

IS

IS

Bach

1998

BTB

94

70

26

4

IS

IS

Barrett*

1996

BTB

83

89

10

1

IS

IS

Beynnon

2002

BTB

22

IS

IS

Eriksson

2001

BTB

80

3

IS

IS

Feagin

1997

BTB

91

11

IS

IS

Marumo

2000

BTB

42

28

IS

IS

O’Neill

1996

BTB

40

78

93

17

2

5

IS

IS

O’Neill

1996

BTB

45

78

87

20

11

2

IS

IS

77 49

23 48

62

10

5

(continued)

Stability Results After Anterior Cruciate Ligament Reconstruction

Aglietti

69

543

544 Author

Year

Graft

KT


2


2x
3 >2 3–4

3–5 >3 4

4–5

>4 >5

6–7

>7 Fixation–

Pop.

IS

IS

1998

BTB

75

67

29

4

Sgaglione

1997

BTB

45

75

18

7

IS

IS

Sgaglione

1997

BTB

41

78

15

7

IS

IS

Shaieb

2002

BTB

24

79

8

13

IS

IS

Tan

1997

BTB

41

3

IS

IS

Wagner

2005

BTB

55

5

IS

IS

Weighted mean (Subgroup 7)

7

55

40

68

1

Fem

Plancher

90

3

Fixation–

Tib

5.0

O-BTB: Other BTB fixation: non-interference screw fixation on tibia, femur, or both (Subgroup 8) Aglietti

Feb

BTB

30

40

43

17

Sc-WS

Sc-WS

BTB

89

49

35

16

ISþBu

IS–Bu

56

32

12

ISþSP

PFBþSP

17

IS

Sc-WS

WS

EB

PFB

PFB

St

IS

1997 Aglietti

Mar 1997

Aglietti

1992

BTB

62

Aglietti

1991

BTB

65

Anderson

2001

BTB

35

Barrett

2002

BTB

37

Buss

1993

BTB

56

64

Feller*

2003

BTB

21

95

5

0

Sc-WS

PFB

Gobbi*

July

BTB

40

90

8

2

IS

EB

BTB

40

78

10

12

ISþBu

63 71

20 29

86 84

8 29

6 9

7

2003 Heier

1997

ISþBu or St

Hertel

2005

BTB

95

59

41

O’Brien

1991

BTB

79

76

Patel

2000

BTB

32

87

Shelbourne

2000

BTB

100

84

0

ISþBu

PFBþBu

4

ISþBu

Bu

13

0

Sc-LW

IS

13

2

Bu

Bu

16 4

Anterior Cruciate Ligament Reconstruction

TABLE 69-1—Clinical Series Divided by Graft and Fixation Method (Cont’d)

Author

Year

Graft

KT


2


2x
3 >2 3–4

3–5 >3 4

4–5

>4 >5

6–7

Pop.

>7 Fixation– Tib

Weighted mean (Subgroup 8)

63

7.4

T-BPTB: Total BPTB: 21S-BPTB and O-BPTB combined

66

5.9

Fixation– Fem

weighted mean Quadriceps tendon graft Lee

2004

Quad

67

T-autograft

75

19

71

6.0 5.2

ALLOGRAFT SERIES BPTB: Nonirradiated (Subgroup 9) Barrett

2005

10-mm

38

74

86

5

7.0

SPþIS or Bu

BPTB Bach*{

2005

10-mm

IS, EB, or

FF

IS/EB 60

82

95

5

0.0

36

65

75

19

5.6

27

4.0

2

IS

IS

FF

IS

IS

IS

IS

FF

IS

IS

IS

IS

IS

FF

BPTB Kleipool

1998

10-mm BPTB

Siebold{

2003

10-mm

183

58

15

BPTB 1996

BPTB

64

20.0

Peterson{

2001

15-mm

30

63

73

27

0.0

30

63

73

23

3.3

IS

IS

FF

64

45

52

33

12.0 16

IS

IS

FF

3

BPTB Shelton

1997

15-mm BPTB

Noyes{

1991

9-10-mm BPTB

Weighted mean (Subgroup 9)

62

11.5

FF

BPTB: Irradiated (Subgroup 10) Noyes{ Gorschewsky

{

FF 1997

BPTB

34

44

2005

Tutoplast

85

27

32

24.0 30 45

2.5 Mrad IS

IS

1.5 Mrad/ acetone (continued)

Stability Results After Anterior Cruciate Ligament Reconstruction

Harner

69

545

546 Author

Year

Graft

KT


2


2x
3 >2 3–4

3–5 >3 4

4–5

>4 >5

6–7

Pop.

>7 Fixation–

Fixation–

Tib

Fem

IS

IS

CP

St/IS

IS

FF

IS

IS

FF or FD

St

St

D

IS

IS

FF or FD

Sc-P

Sc-P

FF

22.0 36

WSP

WSP

FD, EO

20

3.0

?

?

FD, EO, FF

8

8.0

IS

IS

?

Weighted mean (Subgroup 10)

32

40.7

Weighted mean (all BPTB allograft)

56

17.1

Soft-tissue graft: nonirradiated Indelli Siebold

{

Nyland

2003

Achilles

50

66

32

2.0

2003

Achilles

42

71

21

2.0

2003

Tibialis

18

72

22

6.0

77

15

8.0

7

anterior Pritchard{

1995

Fascia lata

39

1994

Achilles or

181

19

Mixed grafts: nonirradiated Levitt

13.0

BPTB Noyes{

1991

9-10-mm

40

63

73

36

15

17

22

5.0

7

BPTBþITB Roberts{

1991

BPTB or BPTBþITB

Noyes

1996

Fascia lata

66

74

or BPTB {

Chang

2003

14-mm

37

65

76

16

BPTBþITB WEIGHTED MEAN (all soft tissue and mixed)

64

12

WEIGHTED MEAN (all nonirradiated grafts)

63

12

WEIGHTED MEAN (all allografts)

59

15

*After author indicates high-stability series (80% normal and
3% abnormal stability). {For allograft series, graft failures that did not result in a side-to-side laxity difference of >5 mm were included in our calculations in the >5þ column. Note: Arthrometric data were reported differently by different authors. The various categories in the column headings reflect the different criteria used in millimeters of side to side difference.
2x denotes extrapolated
2 data, as described in the text. BB, Bone bridge; BMS, bone mulch screw; Bu, simple button; CP, cryopreserved; EB, Endobutton; EO, ethylene oxide; FD, freeze-dried; FF, fresh frozen; IS, interference screw; KT Pop, KT-1000 study population; NI, natural insertion left intact; PFB, press-fit bone; Sc-Lp, graft looped around cortical screw; Sc-LW, cortical screw with ligament washer; Sc-WS, cortical screw with whipstitches; St, staple; WL, WasherLoc; BTB, bone–tendon–bone; BPTB, bone–patellar tendon–bone.

Anterior Cruciate Ligament Reconstruction

TABLE 69-1—Clinical Series Divided by Graft and Fixation Method (Cont’d)

Stability Results After Anterior Cruciate Ligament Reconstruction achieved when the side-to-side difference (SSD) between the knees is 0. Measurement error increases this criterion to 1 mm. Thus we propose a SSD of 1 mm as defining knee stability symmetry. The IKDC “normal” criterion of up to a 2-mm difference may be satisfactory, but it is not truly normal. Indeed, a 2-mm SSD is what is commonly seen with partially torn ACLs.67 When the 1-mm criterion is applied, we see the following: For all autografts, about 30% have greater than 2-mm SSD.68 The remaining 70% fall into four categories: 2 mm, 1 mm, 0, or less than 0. If we assume that one-fourth of the 70% falls into each of these four categories, then it is reasonable to estimate that one-fourth of 70%, or 18%, are exactly 2 mm different. Adding this 18% (exactly 2 mm) to the 30% (greater than 2 mm) would mean that 48% of the reconstructed population has a 2-mm or greater SSD. This leaves about 52% with 1 mm or less SSD (i.e., true symmetry with the other knee). Thus roughly one-half of the autograft ACLRs, in the hands of the experienced knee surgeons who are the authors of these studies, have stability that is either equivalent to a partially torn ACL or worse. The allograft data68 show significantly lower stability rates (see Table 69-1). Table 69-1 presents the raw data for stability from all the studies. The principal areas of interest are the “normal” and “abnormal” stability columns. Abnormal stability in most cases is equivalent to graft failure. The primary table subdivision is by graft type. These are four-strand hamstring (4HS) autograft, two-strand hamstring (2HS) autograft, BPTB autograft, and quadriceps tendon autograft and allograft. The secondary subdivision is by graft subgroup and by fixation type. Subdividing by fixation groups is possible to do with the autografts because of the large number of studies. It is only possible with the allografts to break out a BPTB/interference subgroup because of the smaller number of studies.

stability rate of 56% (P