VOLUME 14 NUMBER 3 PAGES 241–352 June 2009
Editors
International Advisory Board
Ann Moore PhD, GradDipPhys, FCSP, CertEd, FMACP Clinical Research Centre for Health Professions University of Brighton Aldro Building, 49 Darley Road Eastbourne BN20 7UR, UK Gwendolen Jull PhD, MPhty, Grad Dip ManTher, FACP Department of Physiotherapy University of Queensland Brisbane QLD 4072, Australia
K. Bennell (Melbourne, Australia) K. Burton (Huddersfield, UK) B. Carstensen (Frederiksberg, Denmark) J. Cleland (Concord, NH, USA) M. Coppieters (Brisbane, Australia) E. Cruz (Setubal, Portugal) L. Danneels (Maríakerke, Belgium) I. Diener (Stellenbosch, South Africa) S. Durrell (London, UK) S. Edmondston (Perth, Australia) L. Exelby (Biggleswade, UK) J. Greening (London, UK) A. Gross (Hamilton, Canada) T. Hall (Perth, Australia) W. Hing (Auckland, New Zealand) M. Jones (Adelaide, Australia) B.W. Koes (Amsterdam, The Netherlands) J. Langendoen (Kempten, Germany) D. Lawrence (Davenport, IA, USA) D. Lee (Delta, Canada) R. Lee (London, UK) C. Liebenson (Los Angeles, CA, USA) L. Maffey-Ward (Calgary, Canada) E. Maheu (Quebec, Canada) C. McCarthy (Coventry, UK) J. McConnell (Northbridge, Australia) S. Mercer (Brisbane, Australia) P. Michaelson (Luleå, Sweden) D. Newham (London, UK) J. Ng (Hung Hom, Hong Kong) S. O’Leary (Brisbane, Australia) N. Osbourne (Bournemouth, UK) M. Paatelma (Jyvaskyla, Finland) N. Petty (Eastbourne, UK) A. Pool-Goudzwaard (The Netherlands) M. Pope (Aberdeen, UK) G. Rankin (London, UK) E. Rasmussen Barr (Stockholm, Sweden) D. Reid (Auckland, New Zealand) A. Rushton (Birmingham, UK) M. Shacklock (Adelaide, Australia) D. Shirley (Sydney, Australia) C. Snijders (Rotterdam, The Netherlands) P. Spencer (Barnstaple, UK) M. Sterling (Brisbane, Australia) M. Stokes (Southampton, UK) P. Tehan (Melbourne, Australia) M. Testa (Alassio, Italy) P. van der Wurff (Doorn, The Netherlands) P. van Roy (Brussels, Belgium) O. Vasseljen (Trondheim, Norway) B.Vicenzino (Brisbane, Australia) M. Wessely (Paris, France) A. Wright (Perth, Australia) M. Zusman (Perth, Australia)
Associate Editor’s Darren A. Rivett PhD, MAppSc, (ManipPhty) GradDipManTher, BAppSc (Phty) Discipline of Physiotherapy Faculty of Health The University of Newcastle Callaghan, NSW 2308, Australia E-mail:
[email protected] Deborah Falla PhD, BPhty(Hons) Department of Health Science and Technology Aalborg University, Fredrik BajersVej 7, D-3, DK-9220 Aalborg Denmark Email:
[email protected] Tim McClune D.O. Spinal Research Unit. University of Huddersfield 30 Queen Street Huddersfield HD12SP, UK E-mail:
[email protected] Editorial Committee Timothy W Flynn PhD, PT, OCS, FAAOMPT RHSHP-Department of Physical Therapy Regis University Denver, CO 80221-1099 USA Email:
[email protected] Masterclass Editor Karen Beeton PhD, MPhty, BSc(Hons), MCSP MACP ex officio member Associate Head of School (Professional Development) School of Health and Emergency Professions University of Hertfordshire College Lane Hatfield AL10 9AB, UK E-mail:
[email protected] Case Reports & Professional Issues Editor Jeffrey D. Boyling MSc, BPhty, GradDipAdvManTher, MCSP, MErgS Jeffrey Boyling Associates Broadway Chambers Hammersmith Broadway London W6 7AF, UK E-mail:
[email protected] Book Review Editor Raymond Swinkels PhD, PT, MT Ulenpas 80 5655 JD Eindoven The Netherlands E-mail:
[email protected] Visit the journal website at http://www.elsevier.com/math doi:10.1016/S1356-689X(09)00018-6
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Manual Therapy 14 (2009) 241e242 www.elsevier.com/math
Editorial
Standardized clinical data collection and agreed outcome measurement Clinicians increasingly need comprehensive data concerning their performance in healthcare delivery in order to enhance their skills. This is consistent with the professional need and desire for mechanisms to support reflective practice and personal professional growth as well as to, demonstrate evidence of continuing professional development, Alongside this issue is the pressure from national health organizations, managers of health service departments and practices, together with clinical interest groups, to provide data on which to underpin financial commitment to health service provision. The concept of standardized baseline clinical data collection is growing in popularity with many individual services adopting varied approaches to data collection. Recently in the United Kingdom the Department of Health has developed a minimum data set for voluntary use in National Health Service hospital trust departments. The data set consists of comprehensive appointment and referral data focused predominantly on waiting times. This initiative was designed to help attain a reduction of waiting times for patients reaching definitive treatment to 18 weeks or less across a range of services and combinations of services. This initiative is of significant relevance to musculoskeletal outpatient physiotherapy services as physiotherapy treatment can often occur during the pathway to definitive surgery or indeed can represent ‘‘the’’ definitive treatment. It has been mooted that the use of the minimum data set may become mandatory by the year 2010. This initiative has been accompanied by the development of a health service-wide outcome metrics system which is currently being trialed in a small number of hospitals within the UK. This is known as the Care Records Service which is designed to standardize the outcome measures used across healthcare provision within all clinical settings and between disciplines involved in healthcare delivery. This has met with some resistance and considerable debate as in many cases there is a feeling that the outcomes currently included in the metrics system do not necessarily serve the interests of a wide range of 1356-689X/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.math.2009.03.002
health professionals, especially allied health professionals and indeed will not capture at all, patient focused outcomes for patients who have experienced healthcare delivery by health professionals other than those directly involved in surgical or medical interventions. The system is still under development. Effectively, this is a database of validated reliable outcome measures which have been tested for reliability and validity in some contexts, but not in many others! The difficulty of determining a small collection of valid and reliable outcome measures deemed appropriate for use for all patients, even for one type of physiotherapy specialty, has proved to be very difficult, particularly when trying to incorporate patients’ needs, desires and expectations. This exercise in the UK has again highlighted the need for rigorously developed outcome measures which are relevant to patients and therapists across specialties and which are simple to use and which are suitable for routine use within day-to-day practice. To this end it would be a great strength across all musculoskeletal physiotherapy services if an appropriate outcome measure could be agreed upon at national or even international levels and which would serve the needs of patients, therapists and health service managers. Standardized data collection has been on a number of agendas for some time and is gaining momentum to serve political needs, to underpin tendering for service provision, to highlight profile of patients accessing local and regional services and in helping to establish which kind of expertise is needed in the workforce to fulfill local healthcare provision needs. It is also essential to establish training needs within a local workforce. Rigorous standardized data collection can highlight the effectiveness of the service in fulfilling the desirable outcomes of musculoskeletal care in outpatient physiotherapy settings, such as, return to work and keeping individuals at work and the attainment of joint, ie patient and therapist joint treatment goals. Coupled with validated outcome measures, standardized data collection can prove a strong and viable mechanism for
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Editorial / Manual Therapy 14 (2009) 241e242
ensuring maximum patient benefit of services delivered, underpinning service improvements, for maximizing skills available within the clinical workforce and indicating the cost efficiency of the cost in question. Importantly this method of data collection can also indicate how local health service delivery is fulfilling government and national health service agendas. The important point here is local ‘buy in’ and feelings of ownership. Those involved in standardized clinical data collection must all be aware of the possible benefits to them as individuals and to their patients and the service in which they operate. Whatever tool is used to collect data, it must be developed rigorously using consensus methods. It is vital to have strong data to support our service delivery and outcome measurement. The data must be understandable and acceptable to other professions as well as health service managers. It must increase musculoskeletal physiotherapists’ and other physiotherapists’ visibility in health service delivery, justify and
underpin current practices and indeed justify, if relevant, the expansion of musculoskeletal services. The important questions that all musculoskeletal physiotherapists and other practitioners should ask is: What data do we need to collect in order to justify our services and what would be the most appropriate outcome measure to use to indicate the effectiveness of our services? This activity can be a very useful in-service training activity whilst developing consensus and also helps individual staff to feel ownership of whatever system is established. The importance of this work cannot be underestimated. Equally, sharing of any data collected across areas of service delivery, and across hospital trusts and/or individual practices, can create healthy debate and stimulate intellectual and clinical growth. Ann Moore* Gwen Jull *Corresponding author. Tel./fax: þ44 1273 643766. E-mail address:
[email protected] Available online at www.sciencedirect.com
Manual Therapy 14 (2009) 243e251 www.elsevier.com/math
Original Article
Perceptions and use of passive intervertebral motion assessment of the spine: A survey among physiotherapists specializing in manual therapy Emiel van Trijffel a,*, Rob A.B. Oostendorp b, Robert Lindeboom a, Patrick M.M. Bossuyt a, Cees Lucas a a
Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands b Research Centre for Allied Health Sciences, Department of Quality of Care Research, University Medical Centre St Radboud, Nijmegen, The Netherlands
Received 11 September 2007; received in revised form 28 January 2008; accepted 7 February 2008
Abstract Manual therapists commonly use passive intervertebral motion (PIVM) assessment within physical examination. Data describing the use and interpretation of this manual diagnostic procedure, as well as therapists’ perception of related importance and confidence, are lacking. A survey was conducted among Dutch physiotherapists specializing in manual therapy (MT) using a 13-item, selfadministered, structured questionnaire. Three hundred and sixty-seven questionnaires were analysed. Response rate from the postal part of the survey was 56%. Dutch manual therapists most frequently apply passive segmental motion assessment to the cervical region and they prefer three-dimensionally coupled motions. They consider end-feel or, to a lesser extent, provocation of patient’s pain as decisive for diagnostic conclusions. Respondents believe that these spinal motion tests are important for treatment decisions and are confident in their conclusions drawn from it. These perceptions were largely stable across subgroups of therapists with different gender, age, experience, and educational background. Weekly amount of work related to spinal disorders was positively associated with perceived importance and confidence. Reported use and interpretation of PIVM assessment and related perceptions could only partly be substantiated by evidence. Results from this survey will help researchers design studies better reflecting daily practice in MT. Ó 2008 Elsevier Ltd. All rights reserved. Keywords: Manual therapy; Range of motion, articular; Physical examination; Spine
1. Introduction The Dutch Association for Manual Therapy describes manual therapy (MT) as a specialization within * Corresponding author. Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Academic Medical Centre, University of Amsterdam, PO Box 22700, 1100 DE Amsterdam, The Netherlands. Tel.: þ31 10 4527409. E-mail address: e.vantrijff
[email protected] (E. van Trijffel). 1356-689X/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.math.2008.02.005
physiotherapy characterized by the analysis, interpretation and treatment of complex health problems resulting from arthrogenic, muscular and neurogenic disorders of the spinal column and extremities using specific manual diagnostic and manual therapeutic techniques (Dutch Association for Manual Therapy, 2005). Contrary to many other countries, in The Netherlands, MT is considered a post-graduate (non-university) specialization within physiotherapy providing practitioners additional knowledge and skills for manual diagnosis and
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high-velocity thrust interventions (Oostendorp et al., 2004; Oostendorp et al., 2006). Dutch physiotherapists specializing in MT (manual therapists) have explicitly been profiling themselves as specialists in the care of health problems arising from spine-related disorders (Dutch Association for Manual Therapy, 2001). MT is characterized by the skill of therapists to induce articulatory movements manually in joints of spinal motion segments, like, for instance, passive physiological and accessory movements (Farrell and Jensen, 1992; Maher and Latimer, 1992; Dutch Association for Manual Therapy, 2005; Van Ravensberg et al., 2005). From a diagnostic perspective, judging the quantity and quality of passive segmental intervertebral joint motion contributes to classification of patients (Jull et al., 1994). Little is known about how manual therapists and physiotherapists use and interpret passive intervertebral motion (PIVM) assessment within clinical decisionmaking. Dutch manual therapists significantly more often detected impairments of joint mobility than Dutch physiotherapists did (Van Ravensberg et al., 2005; Oostendorp et al., 2006). Manual therapists participating in these studies believed ‘joint range-of-motion’ and ‘manual end-feel’ are relevant indicators of such impairments. A survey among orthopaedic certified specialists from the American Physical Therapy Association revealed that ‘segmental mobility testing or pain provocation’ was often used for the diagnosis of clinical lumbar instability (Cook et al., 2005). Australian physiotherapists rated the presence of an ‘excessively free end-feel’ on passive motion testing as highly important in the recognition of minor cervical instability (Niere and Torney, 2004). However, it remains unclear how manual therapists use, judge, and interpret PIVM assessment within their diagnostic reasoning leading to therapy decisions. In addition, it is unknown to what extent they believe this diagnostic procedure is important for decision-making or how confident they are in their conclusions drawn from it. A cross-sectional study using a self-administered survey questionnaire was conducted to describe and explore the use of PIVM assessment by Dutch physiotherapists specializing in MT and, additionally, to identify factors associated with therapists’ perception of related importance and confidence.
2. Methods 2.1. Survey instrument We developed a 13-item, structured questionnaire aimed at exploring the following three domains: demographic and professional characteristics, the use of PIVM assessment, and perceived importance and confidence related to PIVM assessment (Table 1).
Table 1 Survey instrument consisting of 13 items divided into three domains. Domain
Items
1. Demographic and professional characteristics
Gender Age Weekly amount of work related to spinal disorders MT educational background Experience in MT
2. Use of PIVM assessment in daily practice
Most frequently examined spinal region Most frequently applied type of movement Most decisive clinical finding Scale(s) used for categorizing clinical findings Term(s) used for recording of identified impairments of function of motion segments
3. Perceived importance and confidence related to PIVM assessment
Importance of PIVM assessment for therapy decisions Confidence in reaching correct diagnostic conclusions with PIVM assessment Confidence in reaching the same diagnostic conclusions with PIVM assessment compared to a random colleague
Note: MT: manual therapy, and PIVM: passive intervertebral motion.
In the second domain, two open-ended questions were used inviting respondents to describe types of scales used for classifying clinical findings and terms used for recording of identified impairments of function of motion segments in patient records. Furthermore, see Appendix for definitions of types of movements applied for PIVM assessment (Huijbregts, 2002; Cook, 2003; Brisme´e et al., 2006; Cook et al., 2006). In the third domain, respondents rated their perceived importance and confidence on a seven-point rating scale. 2.2. Procedure The questionnaire was tested for interpretability in two groups of manual therapists constituting consultation platforms. These platforms are part of the quality assurance program of the Royal Dutch Society for Physical Therapy and generally consist of up to 15 therapists working on quality improvement and assurance (Van der Wees et al., 2003). These testing rounds led to minor rephrasing of two items. Completing the questionnaire took 3e5 min. The final version of the questionnaire was sent by e-mail to all practices in The Netherlands listed under ‘manual therapists’ in the Yellow Pages and the Telephone Guide databases (2006) with a link to their e-mail address (September 2006). Potential respondents were requested to complete the questionnaire and return it by e-mail within 3 weeks. Consequently, from a single practice, more than one manual therapist could potentially respond. A reminder, accompanied by a new copy of the questionnaire, was sent after 1 month. Next, questionnaires were sent by post to all 23 MT consultation
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platforms in The Netherlands (November 2006). Members were asked to complete the questionnaires during their next meeting and return these using a prepaid and pre-addressed envelope. After 2 months, a reminder was sent in which the opportunity was given to request for new copies of the questionnaire. Finally, a random selection of 200 manual therapists out of 2796 (as at 1 January 2007) registered in the Quality Register of the Royal Dutch Society for Physical Therapy (2007) received a copy of the questionnaire by post (February 2007). Simultaneously, a random sample of 200 practices for MT listed in the Telephone Guide database (2007) also received one questionnaire each by post. Practices involved in the e-mail survey were excluded. Wherever possible, personal addressing was used. Respondents were asked to complete and return the questionnaire within 3 weeks using a prepaid and pre-addressed envelope. No reminder was sent. We incorporated methods that have been proven to increase response rates to postal questionnaires (Edwards et al., 2003). Potential respondents were informed by means of a cover letter explaining the purpose of the study. In case of multiple choice items, they were explicitly requested to select one answer only. It was also pointed out to them that data processing would be carried out anonymously. They were explicitly asked not to return questionnaires twice. 2.3. Statistical analysis Absolute and relative frequencies were used to describe categorical data. Ordinal data relating to the perceived importance and confidence items from the third domain of the questionnaire were additionally described with their medians and interquartile ranges (IQR). Normally distributed numerical data were summarized by their means and standard deviations. In case of non-normal distribution, median and range were presented. Answers to the two open-ended questions in the second domain were recorded and ranked according to reported frequency. Internal consistency reliability of the domain containing the importance and confidence items relating to conclusions drawn from PIVM assessment was calculated using Cronbach’s alpha. An alpha > 0.70 indicates homogeneity of the domain and consistency in scoring among respondents (Streiner and Norman, 2003). Rasch rating scale analysis was used to examine reliability of the rating scale structure of the importance and confidence items using an item response theory measurement model and OPLM, a computer software program for Rasch measurement models (Verhelst et al., 1995). Guided by this rating scale analysis, rating categories were dichotomized to obtain the best discrimination between respondents’ perceptions. Subsequently, univariate logistic regression was performed to identify demographic and professional
characteristics of respondents that were associated with perceived importance and confidence. Strengths of associations were expressed as odds ratios (OR) with their 95% confidence intervals and corresponding p-values. An OR of 1 indicates no association between the importance or confidence item and the demographic or professional characteristic, while an OR much greater or less than 1 indicates stronger associations. All analyses were carried out in SPSS (version 14.0). Missing data were not replaced. Multiple answers to multiple choice questions were handled as missing.
3. Results 3.1. Response rates From 858 citations found in the Yellow Pages and 1079 found in the Telephone Guide, 178 and 128 practices, respectively, had a link to their e-mail address. Twenty-eight practices responded within 3 weeks and returned 33 questionnaires. After the reminder, another 21 questionnaires (21 practices) were received bringing the e-mail response rate to 16% (49/306). Ten consultation platforms responded by returning 68 questionnaires. After the reminder, another 22 questionnaires were sent by two platforms yielding a response rate of 52% (12/23). Finally, 223 (56%) completed questionnaires were returned by post. In total, 367 questionnaires, containing 31 (0.7%) missing data, were analysed. 3.2. Descriptive findings Demographic and professional characteristics of the survey sample are summarized in Table 2.
Table 2 Demographic and professional characteristics of the survey sample (n ¼ 367). Male gender Mean age (SD) Weekly amount of work related to spinal disordersa MT educational background SOMT MT Utrecht (Van der Bijl) Maitland’s Concept Vrije University Brussels Master MT Orthopaedic MT Other More than one Experience in MTa
281 (76.6%), missing 0 46.1 (8.0) yrs, missing 0 24.0 (1.0e55.0) h, missing 6
241 39 19 3
(66.8%) (10.8%) (5.3%) (0.8%)
31 5 23 14.0
(8.5%) (1.4%) (6.4%), missing 6 (1.0e40.0) yrs, missing 7
Note: MT: manual therapy, SD: standard deviation, and SOMT: Stichting Opleiding Manuele Therapie. a Data described as median (minimumemaximum).
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E. van Trijffel et al. / Manual Therapy 14 (2009) 243e251 Table 3 Ranked, absolute frequencies of 10 most frequently reported terms for recording of identified impairments of motion segments in patient records (n ¼ 367).
30%
Block Restriction Motion restriction Restricted Functional impairment Hypomobility Hypermobility Instability Hypofunction Dysfunction
20%
10%
n=110
n=102
n=62
n=13
C0-C3
C2-T1
C7-T4
T4-T10
0%
n=6 T10-L2
n=64 L1-S1
Fig. 1. Bar chart showing absolute (in bars) and relative ( y-axis) frequencies of most frequently examined spinal region using PIVM assessment (n ¼ 357).
Two hundred and seventy-four respondents (76.8%) reported applying PIVM assessment most frequently to the cervical region, i.e. motion segments C0eT4 (Fig. 1). When using segmental motion assessment, almost 80% (291/366) of manual therapists most frequently apply three-dimensional (coupled) physiological motions, while 23 (6.3%) indicated they use one-dimensional physiological movements primarily and about 11% (39/366) prefer accessory motion assessment. Forty-eight percent of respondents (176/367) considered perceived resistance at the end of the movement (end-feel) as the most decisive clinical finding from PIVM assessment for making diagnostic conclusions about impairments of joint function of motion segments, while 22.6% (83/367) preferred provocation or reduction of pain or other symptoms for this purpose. Forty-eight (13.1%) therapists reported to judge PIVM primarily on range of motion and 10.4% (38/367) relied on perceived resistance during movement. Ninety-two manual therapists (25.1%) stated they made explicit use of scales for categorizing clinical findings from PIVM assessment. For classifying end-feel (19 times), scales were used with terms like ‘hard’, ‘empty’, ‘springy’, and ‘stiff’ reported most often. Visual analogue scales (22 times) were the scale of choice for measuring patient’s pain. Nine therapists reported their use of Maitland’s movement diagram for grading mobility and a three-point scale (hypomobileenormalehypermobile) for this purpose was mentioned seven times. In total, 67 different terms were given for the recording of identified impairments of motion segments in
77 47 38 34 28 19 17 13 8 6
patient records. Table 3 shows 10 most frequently reported terms. Some respondents additionally record segmental level (35 times) or motion direction (36) of impairments, or both (24). In Table 4, frequencies of scores on the importance and confidence items are presented. Eighty-one percent (296/367) of respondents believed that diagnostic conclusions from PIVM assessment were reasonably or very important for deciding on MT as a treatment option (IQR ‘reasonably important’ to ‘very important’). With respect to perceived confidence in diagnostic conclusions drawn from PIVM assessment, 198 therapists (54.0%) were reasonably confident that they would reach a correct diagnosis about impairments of function of motion segments (IQR ‘somewhat confident’ to ‘reasonably confident’), while 251 (68.4%) were somewhat or reasonably confident that they would reach the same conclusions as a random colleague (IQR ‘neutral’ to ‘reasonably confident’). Cronbach’s alpha for the total domain was 0.75, indicating that, on the whole, respondents were consistent in their reporting of perceptions. 3.3. Inferential findings Rating scale analysis indicated that collapsing the ‘reasonably important’ and ‘very important’ and the ‘reasonably confident’ and ‘very confident’ categories versus the collapsed remaining five categories, offered the best differentiation between respondents’ scores on perceived importance and confidence regarding the use of PIVM assessment. ORs representing strengths of associations between the three recoded dichotomous variables on the one hand and demographic and professional characteristics on the other are shown in Table 5. Weekly amount of work related to spinal disorders was positively associated with all perceptions of importance and confidence. This means, for example, that for every additional weekly hour spent on treating patients with health problems arising from disorders of the vertebral column, there was a 3% higher chance (odds) to believe
Table 4 Frequencies of scores on perceived importance and confidence related to PIVM assessment (n ¼ 367). How important to you are diagnostic conclusions from PIVM assessment for deciding on manual therapy as a treatment option? Very unimportant 5 (1.4%)
Reasonably unimportant 3 (0.8%)
Somewhat unimportant 2 (0.5%)
Neutral 5 (1.4%)
Somewhat important 56 (15.3%)
Reasonably important 198a (53.9%)
Very important 98 (26.7%)
How confident are you by using PIVM assessment in reaching the correct diagnostic conclusions with regard to impairments of motion segments? Very unconfident 5 (1.4%)
Reasonably unconfident 10 (2.7%)
Somewhat unconfident 16 (4.4%)
Neutral 29 (7.9%)
Somewhat confident 99 (26.9%)
Reasonably confident 198a (54.0%)
Very confident 10 (2.7%)
Very unconfident 11 (3.0%) a
Reasonably unconfident 20 (5.4%)
Somewhat unconfident 31 (8.4%)
Neutral 45 (12.3%)
Somewhat confident 113a (30.8%)
Reasonably confident 138 (37.6%)
Very confident 9 (2.5%)
Median score.
Table 5 Univariate logistic regression analysis using scores on importance and confidence regarding PIVM assessment as dependent factors and demographic and professional characteristics as independent explanatory variables (n ¼ 367). Characteristic
Male gender Age Weekly amount of work related to spinal disorders MT educational backgrounda Maitland’s Concept Orthopaedic MT Experience in MT
Importance of PIVM assessment for therapy decisions
Confidence in reaching correct diagnostic conclusions with PIVM assessment
Confidence in reaching the same diagnostic conclusions with PIVM assessment compared to a colleague
OR
95% CI
p-Value
OR
95% CI
p-Value
OR
95% CI
p-Value
1.31 0.98 1.03
[0.69, 2.49] [0.95, 1.01] [1.01, 1.06]
0.412 0.205 0.033*
0.90 1.03 1.04
[0.55, 1.46] [0.99, 1.05] [1.02, 1.07]
0.665 0.067 0.05). Hardness and fascicle curvature during maximal isometric plantarflexion were significantly greater than those at rest ( p ¼ 0.002 and p < 0.001, respectively). Correlations between changes in fascicle curvature and changes of muscle hardness that took place between muscle relaxation and maximal contraction were significant (r ¼ 0.832, p ¼ 0.011). This study demonstrates that ultrasonographic and myotonometric measurements are useful to quantify changes in muscle geometry and mechanical properties for muscles during isometric contraction. Ó 2008 Elsevier Ltd. All rights reserved. Keywords: Ultrasonography; Muscle architecture; Muscle mechanical property; Muscle contraction
1. Introduction The hardness of human skeletal muscles has been measured noninvasively by hardness meter (Ashina et al., 1998), compartment evaluator (Steinberg and Gelberman, 1994; Steinberg, 2005), and myotonometer (Leonard et al., 2001, 2003, 2004). These instruments measure the displacement of a muscle to which a compressive force is applied perpendicularly. The slope of
* Corresponding author. Tel.: þ886 2 33228134; fax: þ886 2 33228160. E-mail address:
[email protected] (H.-K. Wang). 1356-689X/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.math.2008.02.011
the linear part of the forceedisplacement curve is representative of the mechanical hardness or transverse stiffness of the compressed muscle (Steinberg and Gelberman, 1994; Ashina et al., 1998; Steinberg, 2005). Measurements for the muscle hardness or transverse stiffness are validated by a two-layered spring model representing muscles and surrounding fascia (Horikawa et al., 1993). A greater muscle hardness (transverse stiffness) was found in the affected muscles of patients with compartment syndrome (Steinberg, 2005), cerebral palsy (Aarrestad et al., 2004), hemiparesis (Leonard et al., 2001), and those of healthy subjects after performing eccentric exercises (Murayama et al., 2000). Leonard et al. (2004) found that the transverse stiffness
H.-K. Wang et al. / Manual Therapy 14 (2009) 264e269
of myotonometric measurements correlates positively with the activity of surface electromyography (EMG) during different levels of voluntary isometric contraction in healthy subjects. Collectively, these studies indicate that muscle hardness is affected by muscle disorders and levels of activation. However, these measurements are performed on the surface of the skin over the muscle, and whether the underlying architecture of the contracting muscle affects the mechanical hardness is unknown. Ultrasonographic measurements of fascicle geometry of the medial gastrocnemius muscle have been confirmed by direct measurement of cadaveric muscles (Narici et al., 1996). Fascicle curvature is defined as the reciprocal of the radius of the fascicle circle (van Leeuwen and Spoor, 1992). Real-time ultrasound has been used to demonstrate that the fascicle of healthily young volunteers is significantly more curved for the medial gastrocnemius muscle during isometric maximal voluntary contraction (MVC) versus the resting state (Muramatsu et al., 2002). Some researchers have suggested the curved muscle fascicle of contracting muscles as a possible cause to explain the elevated intramuscular pressure during isometric contractions (Hill, 1948; Sejersted et al., 1984). To date, the relationship between real-time alterations in the fascicle curvature and changes of muscle hardness in skeletal muscles in vivo is unknown. Thus, the purpose of this study was to analyze the relationship between changes of muscle fascicle curvature and muscle hardness for the medial gastrocnemius muscle in vivo during relaxation and isometric contraction. Potential confounding effects of angle of the ankle joint (Karamanidis et al., 2005), muscular electrical activities, and maximal plantarflexion force were controlled to ensure a standardized protocol.
2. Material and methods 2.1. Subjects Our institutional review board approved this study, and all subjects provided informed written consent. Inclusion criteria were subjects without any history of knee, leg, and ankle pain during their lifetime. Twenty-one male students were recruited through a sports center at a university. All subjects played in recreational clubs including tennis, volleyball, and basketball. The morphology, architecture, and contractile capacity of human pinnate muscles respond to intensive training (Aagaard et al., 2001). Therefore, four students were excluded to reduce confounding effects of training, because they had been training for their specific sport since teenagers. Data of 17 college students (age 21.0 1.5 years; body height 171.4 7.4 cm; weight 63.8 7.6 kg) were analyzed.
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2.2. Experiment protocol After a 5-min warm-up session, each subject lay prone on an examination bed with both ankles hanging over the edge of the bed. The lower back and knees of each subject were tightly secured by straps to prevent any trunk, back, or knee movements. All measurements were performed on the right leg, the dominant leg in all subjects, with the foot positioned at 90 relative to the tibia and fixed on a footplate. Leg dominance was determined by asking subjects which leg they used to kick a ball, this was the dominant leg. Because the ultrasound and myotonometer could not be applied at the same time, the subjects were randomly assigned to one of two testing sequences: either the ultrasound first and then the myotonometer 20 min later, or vice versa. During each test, subjects were asked to perform at least two repetitions of a 5-s muscle relaxation and a 5-s maximal isometric plantarflexion, with a 2-min rest between each repetition. In each repetition, three myotonometric and ultrasonographic measures (measure interval 1.5 s) were made in 5 s for (1) muscle relaxation and (2) isometric plantarflexion, at approximately 1, 2.5, and 4 s. Synchronized recordings of the electrogoniometer, surface EMG, and force were made simultaneously. Forces of plantarflexion (kg), plantarflexion angle of ankle joint ( ), and root mean square of electromyographic amplitude (mV) corresponding to the time of three myotonometric or ultrasonographic measurements performed were averaged. Variables were then averaged over the repetitions. The effectiveness of the ankle fixation method was assessed using an electrogoniometer (Sharp Sensor S700, Measurand Inc., Fredericton, Canada). In addition, muscular activities from the gastrocnemius medialis were recorded by EMG using one channel bipolar Ag/ AgCl surface electrodes (Model: MP100WSW, Biopac Systems Inc., Goleta, USA). With the right foot fixed, maximal plantarflexion force (kg) was recorded by a load cell (Model: S6001, Celtron Techniques Inc., Taipei, Taiwan) connected to the footplate. The signals of the eletrogoniometer, surface EMG, and load cell were stored on a personal computer (ASUS D672, Taipei, Taiwan, ROC) at 1200, 1200, and 200 Hz, respectively, via an A/D converter (Model: MP100WSW, Biopac Systems Inc., Goleta, USA). Real-time development or changes of the force, amplitudes of surface EMG, and angle of the ankle joint were displayed on a computer monitor with a software window (AcqKnowledge software, Biopac System Inc., Goleta, USA). During relaxation, no significant electromyographic activities of the muscle were observed. Maximal isometric plantarflexion was defined as the greatest value for the real-time force for which no further increase was observed. The electrogoniometer measured the dorsiflexion/ plantarflexion (in degree) of the ankle joint when the
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ends of the goniometer were fixed to the medial side of the lower leg parallel to the tibial bone and to the medial side of the foot parallel to the first metatarsal bone. Electromyographic activity was recorded from the midline of the gastrocnemius medialis muscle, guided by axial-plane ultrasonographic scanning. Skin preparation was taken prior to application of surface electrodes and a portable EMG instrument e Seirra II (Cadwell, Kennewick, WA, USA) e was used to ensure that the interelectrode resistance was below 5 kU. Surface electrodes with a diameter of 5 mm were placed with an interelectrode distance of 20 mm at a site corresponding to the proximal third of the gastrocnemius muscle with the reference electrode placed on the lateral malleolus of the left ankle. The raw electromyographic signal was preamplified and filtered using high- and low-pass filters set at 10 and 500 Hz, respectively (pre-amplifier: common mode rejection ratio ¼ 95 dB; impedance ¼ 100 MU; gain ¼ 350). Amplitudes (root mean square; mV) of the surface EMG were quantified for a 1/10 s epoch corresponding to the middle of each myotonometric measurement or ultrasonographic image. Measurements of muscle hardness were performed on the medial gastrocnemius muscle with a hand-held muscle hardness meter (Fig. 1) myotonometer (Neurogenic Technologies Inc., Missoula, USA). The head of the myotonometer probe (diameter: 1.4 cm) was held in a vertical position on the skin surface of the medial gastrocnemius muscle. The measure point of hardness was located at the medial side to midpoint of two recording electrodes on the gastrocnemius medialis with a distance of 1.5 cm. In each trial, three successive
measurements were performed at 1.5-s intervals with an applied force of approximately 2 kg/s. The amount of force in response to the perturbation was simultaneously recorded with the amount of penetration depth. The myotonometer was connected to a computer (TOSHIBA Satellite M40, Tokyo, Japan; Fig. 1) which provided electrical signals (hardness signal) to the Biopac system for each measurement. These signals were used to synchronize the myotonometer with measurements of root mean square of amplitude, plantarflexion force, and joint angle, using software (LabVIEW 7.1, National Instruments, TX, USA). Pilot work indicated that the curve was linear when the force in response to the perturbation was equal to or greater than 0.25 kg. In this study, muscle hardness was defined as a value obtained from linear portion (from 0.5 to 2.0 kg) of the force responseedepth curve. Hardness (the slope) of the linear part of the curve was calculated using software with best polynomial fitting (MATLAB 7.1, The MathWorks Inc., MA, USA). Intrarater reliability of the myotonometer on the lateral gastrocnemius and biceps brachii muscles varied from 0.84 to 0.99 (Leonard et al., 2003). Ultrasonographic measurements of fascicle curvature were made using a SonoSite 180 plus ultrasound (SonoSite Inc., WA, USA) with a 5e10 MHz broadband linear array transducer. The examiner positioned the probe perpendicular to the surface of the leg in such a manner as to avoid compressing the skin and underlying tissues. The ultrasound probe was placed on the sagittal plane of the gastrocnemius medialis muscle medial and parallel to the long axis of the two recording electrodes with
Fig. 1. Arrangements of myotonometric and ultrasound testing conditions. SE, surface electrodes; EG, electrogoniometer; LC, load cell; FP, footplate; US, ultrasonography; Com-1, recording computer; and Com-2, synchronization computer.
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a distance of 1.5 cm (the same location where the myotonometer was placed). Proximal and distal edges of the ultrasound probe corresponded to the proximal border of the proximal recording electrode and distal border of the distal recording electrode, respectively. The B mode and a view of near field (depth of view: 3.2 cm) with near-field resolution (axial resolution: 0.7 mm) were set when scanning the curvature. The real-time images were recorded using a camera (Handycam DVD803, Sony, Tokyo, Japan) and stored on a disc at 30 Hz. Software containing simulating switching circuits written using LabVIEW 7.1 (National Instruments, TX, USA) was installed in a computer (TOSHIBA Satellite M40, Tokyo, Japan) to add audio-electrical signals to the camera and Biopac system at beginning and end of measurements for synchronization (Fig. 1). Ultrasonographic images were taken at 1, 2.5, and 4 s within the 5-s period of muscle relaxation and repeated for isometric plantarflexion. Thirty ultrasound images are collected during each of the three measurements (at time point 1, 2.5, and 4 s of the 5-s relaxation/contraction). Three images with the best quality in curvature at each time point are used for the determination of fascicle curvature. While scanning, echoes from the interfascicular space were identified and the fascicular path was defined as an arc of a circle between the superior and deep aponeuroses. Determination of the fascicular curvature was made as described by Muramatsu et al. (2002). Fascicle curvature ¼ jcos 2qd cos 2qs j=½2$Muscle thicknessðcos qd þ cos qs Þ: For the meaning of each symbol, see Fig. 2. All morphological measurements were made by the same examiner with software from AutoCAD (AutoCAD,
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Autodesk Inc., CA, USA). Previous work from our laboratory demonstrated that the interday reproducibility of calculating the fascicle curvature on the basis of a coefficient of variation was 10.1%. 2.3. Statistics Bonferroni t-method tested whether variables from surface EMG (mean values of root mean square of amplitude (mV)), electrogoniometer (angle of ankle joint ( )), and load cell (maximal force (kg)) were similar between the myotonometer and ultrasound conditions during isometric plantarflexion. Mean values of muscle hardness and fascicle curvature were compared for the muscle at rest and maximal isometric plantarflexion by paired t test. Correlations between curvature changes and changes of muscle hardness that took place between muscle relaxation and maximal contraction were analyzed by Spearman correlation tests.
3. Results Mean values of root mean square of amplitude (mV), angle of ankle joint ( ), and force of maximal isometric plantarflexion (kg) are summarized in Table 1. No significant differences of these above variables were observed between the myotonometer and ultrasound conditions, suggesting that the configuration was similar for the conditions (all p values > 0.05) (Table 1). Hardness and fascicle curvature of maximal isometric plantarflexion were significantly greater than those of the muscle at rest ( p ¼ 0.002 and p < 0.001, respectively) (Table 2). A significant correlation was found between changes of curvature and muscle hardness in the gastrocnemius medialis (r ¼ 0.832, p ¼ 0.011) (Table 2).
Fig. 2. Ultrasonographic measurements of the fascicle curvature. Fascicle curvature ¼ jcos 2qd cos 2qs j=½2$Muscle thicknessðcos qd þ cos qs Þ: (Muramatsu et al., 2002). qs is the angle formed between the tangent (L3) of the fascicle at the intersection made by the fascicle and the superficial aponeurosis and the tangent (L1) of the deep aponeurosis at the intersection made by the fascicle and the deep aponeurosis. qd is the angle formed between the tangent (L2) of the fascicle at the intersection made by the fascicle and the deep aponeurosis and L1. Results showed qs ¼ 10 ; qd ¼ 19 ; pixel distance which equals to 1.0 cm shows 10.01 and muscle thickness ¼ 1.21 cm in this image (pixel distance ¼ 12.12).
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Table 1 Mean values (standard error) of root mean square of amplitude of the gastrocnemius medialis, angle of ankle joint, and force of maximal isometric plantarflexion in two measure conditions. Ankle joint ( )
Amplitude (mV)
Force (kg)
Myotonometric measurement Ultrasound measurement
88.6 2.7
0.636 0.394
55.7 12.7
89.0 3.1
0.615 0.479
56.2 13.1
p Value
0.138
0. 214
0.775
4. Discussion Physiotherapists often use palpation to evaluate muscular shapes and firmness in conditions of muscle relaxation or contraction. However, quantitative measurements for muscle contraction status are lacking. We used a rigorous and standardized protocol to reduce influences from the joint position and force (Table 1). Results of this study indicate that contracting muscle displays a significantly greater fascicle curvature and muscle hardness compared to the resting muscle (Table 2). As compared with the report by Muramatsu et al. (2002), the curvature observed in contracting muscles was greater in our study (9.4 3.3 versus 5.5 2.2 m1). This may be due to the different methodologies used for curvature measurements. The measurements in this study were performed with a distance of 1.5 cm to long axis of the gastrocnemius medialis muscle, while Muramatsu et al. (2002) conducted their study on the long axis of muscle. Nevertheless, these results confirm previous findings demonstrating that the muscle curvature at maximum contraction was larger, and amounts of muscle displacement to force applied perpendicular to the contracted muscle are less (Muramatsu et al., 2002; Leonard et al., 2004). This indicates that contraction levels affect the muscle architecture and mechanical properties, and measurements of curvature and muscle hardness are capable of objectively assessing these changes. Both curvature and hardness techniques are recommended for studies interested in exploring muscle architecture or mechanical properties during contraction. In addition, our study is the first to demonstrate a significant correlation between the changes of fascicle
Table 2 Mean values (standard error) of muscle hardness and fascicle curvature of the gastrocnemius medialis at muscle relaxation and isometric maximal plantarflexion. Hardness (kg/mm)
Fascicular curvature (m1)
Relaxation Maximal contraction
0.63 0.14 0.86 0.26
0.7 2.0 9.4 3.3
p Value
0.002
4.5 for 89% of the neck-pain subjects and
