Efficacy of Exercise Intervention as Determined by the McKenzie ...

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Mar 1, 2014 - JAMES HOWARD, MD, FRCSC4 • DOUGLAS NAUDIE, MD, FRCSC4 • SHAWN M. ROBBINS, PT, PhD5. Efficacy of Exercise Intervention.

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Journal of Orthopaedic & Sports Physical Therapy® Downloaded from www.jospt.org at University of Western Ontario on March 1, 2014. For personal use only. No other uses without permission. Copyright © 2014 Journal of Orthopaedic & Sports Physical Therapy®. All rights reserved.

RICHARD ROSEDALE, PT, Dip MDT1 • RAVI RASTOGI, PT, MSc, Cred MDT1 • STEPHEN MAY, PT, PhD2 BERT M. CHESWORTH, PhD3 • FRANK FILICE, PT, Cred MDT1 • SEAN WILLIS, PT, Cred MDT1 JAMES HOWARD, MD, FRCSC4 • DOUGLAS NAUDIE, MD, FRCSC4 • SHAWN M. ROBBINS, PT, PhD5

Efficacy of Exercise Intervention as Determined by the McKenzie System of Mechanical Diagnosis and Therapy for Knee Osteoarthritis: A Randomized Controlled Trial TTSTUDY DESIGN: Randomized controlled trial.

TTOBJECTIVES: To examine the efficacy of exer-

cise intervention in patients with knee osteoarthritis (OA), as directed by Mechanical Diagnosis and Therapy (MDT) assessment, and, secondarily, to explore outcomes between MDT assessment–defined subgroups within the exercise group.

TTBACKGROUND: Due to the high physical and

economic burden of knee OA, the effectiveness of conservative interventions and determining those patients who will respond to them should be investigated.

TTMETHODS: Patients with knee OA (n = 180)

were randomized to an exercise intervention group or a control group. The intervention group, in which patients classified as having knee derangements (MDT derangement) received MDT directional exercises and patients classified as nonresponders (MDT nonresponders) received evidence-based exercises, was compared to a control group that received no exercise intervention. Pain and function were assessed at baseline, 2 weeks, and 3 months, using the P4 pain scale and Knee injury and Osteoarthritis Outcome Score (KOOS) pain and function subscales. Two-way analysis of covariance was used to examine treatment and time effects. Multiple comparisons were examined, and

mean differences with 95% confidence intervals (CIs) were reported.

TTRESULTS: The exercise intervention group had

significantly improved P4 scores (mean difference, –6; 95% CI: –8, –3), KOOS pain scores (mean difference, 9; 95% CI: 5, 13), and KOOS function scores (mean difference, 11; 95% CI: 7, 15) compared to those of the control group at 2 weeks. At 3 months, the exercise intervention group had significantly improved KOOS pain scores (mean difference, 7; 95% CI: 3, 11) and KOOS function scores (mean difference, 5; 95% CI: 1, 9) compared to controls.

TTCONCLUSION: Patients with knee OA who were

prescribed exercises based on an MDT assessment had superior outcomes compared to those of waitlist controls. The MDT subgroup of knee derangement may warrant further investigation in patients with knee OA. Protocol registered at ClinicalTrials. gov (NCT01641874).

TTLEVEL OF EVIDENCE: Therapy, level 1b–. J

Orthop Sports Phys Ther 2014;44(3):173-181. Epub 22 January 2014. doi:10.2519/jospt.2014.4791

TTKEY WORDS: derangement, directional preference, knee pain, physical therapy

K

nee osteoarthritis (OA) is one of the leading causes of pain and disability worldwide.43 There is no

known conservative cure for knee OA, but, depending on the severity of the disability, total knee replacement (TKR) has been shown to be an effective procedure in reducing pain and improving function.2,5,11,17,22 However, up to 19% of patients are dissatisfied with their surgical outcome.5 The economic burden is considerable, with the number of TKRs performed continuing to escalate7 and expected to increase exponentially over the next decade.33 This will increase the already significant economic burden of knee OA on the health care system.18 Due to the high prevalence of knee OA and the increasing use of TKR, with its associated risks and economic burden, it is important to explore conservative options. Currently, exercise intervention has been shown to be efficacious14,20,24,43 and

Physiotherapy Department, London Health Sciences Centre, London, Ontario, Canada. 2Faculty of Health and Wellbeing, Sheffield Hallam University, Sheffield, UK. 3Epidemiology and Biostatistics; Department of Physical Therapy Education, Western University of Health Sciences, London, Ontario, Canada. 4Division of Orthopaedic Surgery, Western University of Health Sciences, London, Ontario, Canada. 5Centre for Interdisciplinary Research in Rehabilitation, Constance Lethbridge Rehabilitation Centre; School of Physical and Occupational Therapy, McGill University, Montreal, Quebec, Canada. The International MDT Research Foundation provided funding. The Foundation did not influence any component of the study and did not put any conditions or restrictions on the use or publication of the data. The Western University Research Ethics Board for Health Sciences Research for Human Subjects approved this research protocol. Protocol registered at ClinicalTrials.gov (NCT01641874). Address correspondence to Richard Rosedale, Physiotherapy Department, London Health Sciences Centre, 339 Windermere Road, London, Ontario N6A 5A5 Canada. E-mail: [email protected] t Copyright ©2014 Journal of Orthopaedic & Sports Physical Therapy® 1

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[ is recommended in multiple guidelines10,22,37; however, its treatment effect has been reported to be modest. A 2008 Cochrane review14 of exercise on knees with OA estimated that the treatment effect of a short-term supervised exercise program was small to medium for both pain reduction (standardized mean difference, 0.40) and physical function improvement (standardized mean difference, 0.37). Although the statistical effectiveness of exercise for knee OA has been clearly demonstrated and may be equivalent or better than commonly prescribed medications,10 the effect on pain reduction and function remains modest. It is possible that not all avenues of exercise therapy have been explored and that greater gains may be achieved. To address the persistent and recurrent nature of OA knee symptoms,14 conservative options that focus on self-management would be preferable. One potential exercise-based treatment approach that has been used to treat knee OA is Mechanical Diagnosis and Therapy (MDT). Although the approach has been used clinically to classify extremity joints, there is no published research on MDT to classify and treat individuals presenting with knee OA. The MDT approach has been extensively used to classify and treat patients with spinal pain.9,28,30 Studies have shown the MDT approach to be valid, reliable, able to successfully predict outcomes,9,30 and associated with decreased lumbar surgery rates,34 pain, and disability.9,26 In the spine, there has been a clear trend toward identifying subgroups that may respond well to particular interventions6,15 and help therapists determine prognosis.16,23,42 This trend has yet to be replicated in the extremities. For physiotherapists, the diagnosis of knee OA offers no such indication as to the potential response to intervention. The overall effect of exercise may only be modest, as a subgroup of patients who respond more substantially to this intervention has not yet been identified. An assessment tool to identify a subgroup

research report of patients with knee OA who experience rapid improvement would be valuable and could impact the need for surgery. The most prevalent and well-studied MDT subgroup is the “derangement” classification. This classification has been described in all joints and has been associated with a rapid response to specific end-range exercises, which corresponds to “directional preference.”26,29 A directional preference occurs when a posture or repeated movement in one direction, usually to end range, makes a rapid and lasting positive change in symptoms, function, and/or range. The derangement syndrome has also been reported to exist in the extremities and specifically in the knee. In a recent survey31 of 103 patients with knee pain, 30 MDT-trained physical therapists classified 42% of the patients as having derangements. Directional preferences in the knee can be either of flexion or extension.31 If the response of these derangements in the knee is similar to that in the spine, they may represent a specific subgroup that could be treated with a single exercise intervention and have a positive outcome. This identification and treatment may allow a more specific exercise prescription, based on a directional-preference assessment in patients with knee OA. The primary purpose of the present study was to examine the efficacy of exercise therapy, as determined by MDT assessment and classification, for improving pain and physical function in patients with knee OA compared with a control group that received no intervention. The secondary purpose was to compare the outcomes of the knee-derangement subgroup to those of the nonresponder subgroup and the control group in an exploratory analysis to develop hypotheses for future study.

METHODS Patients

P

atients were recruited from outpatient orthopaedic clinics at a tertiary health care center (London

] Health Sciences Centre, London, Canada) from November 2009 to April 2012. All patients were from waiting lists of 5 orthopaedic surgeons specializing in hip and knee joint replacements. Patients were recruited by staff physiotherapists and, to be included, were required to have had knee pain for greater than 4 months and to have been referred to the orthopaedic clinic with a radiologically confirmed diagnosis of knee OA. Patients were excluded if they were unable to attend exercise-based physiotherapy 2 to 3 times per week over a 2-week period, had neurological conditions affecting the lower extremities, were unable to understand written or spoken English, or were unable to provide informed consent. The study was approved by the Western University Research Ethics Board for Health Sciences Research for Human Subjects, and informed consent was obtained from all patients. Patients were randomly assigned, at a 2:1 ratio, to the exercise intervention group or the control group, respectively, by an independent person using a random-number generator.41 Opaque envelopes were prepared with group assignment and were opened in order as patients were recruited.

Interventions Patients randomized to the exercise intervention were assessed over 2 to 3 sessions by 1 of 3 physiotherapists (F.F., S.W., or R.R.), who were credentialed in the McKenzie MDT system. The assessment consisted of a detailed history focusing on the differential diagnosis of the MDT system classifications. For the purposes of this study, the clinician restricted the focus to subgrouping the exercise intervention group into either the “derangement” classification (MDT derangement) or a nonresponder classification (MDT nonresponder), dependent on whether a directional preference was established. An examination was then performed using a repeated-movement assessment and the retesting of baseline activities (APPENDIX A, available online). In this

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mode, each knee movement was explored separately with repeated end-range exercises in various positions of loading, and the effects on the baseline activity (eg, stair climbing) were sequentially evaluated. This examination attempted to subgroup patient presentations into the MDT classifications. If a direction of knee movement, when performed repeatedly, had a positive and lasting effect on the symptoms, functional baseline activities, and/or range of knee motion, this was deemed the directional preference and a mechanical diagnosis of knee derangement was established for that particular patient. This patient was then allocated to the MDT derangement group. If there was no lasting positive change from these repeated movements, it was deemed not to be a derangement and the patient was allocated to the MDT nonresponder subgroup. The MDT derangement subgroup was given specific end-range exercises in the direction in which the patients had responded. For example, if the directional preference was assessed to be knee flexion, the patient was given end-range knee flexion exercises in an unloaded, semiloaded, or loaded position, based on the loading strategy to which the patient responded best. Exercises were prescribed as 10 repetitions every 2 to 3 hours (APPENDIX A). The MDT nonresponder subgroup was given evidence-based OA knee treatment that consisted of quadriceps strengthening and advice on aerobic exercises, which typically included stationary biking and walking. This regime was consistent with those recommended in current guidelines.10,14,22,37 Patients were instructed to perform these exercises as outlined in APPENDIX A. Patients in both exercise subgroups attended 4 to 6 physiotherapy sessions (2-3 assessments and the rest followups) over a 2-week period. The duration of the initial assessment was up to 1 hour, and that of the follow-up sessions was 20 minutes. The control group remained on the waiting list, to be followed up in the

orthopaedic department at the surgeon’s discretion, and received their usual standard of care.

the secondary outcomes are provided in APPENDIX B (available online).

Statistical Analysis Outcome Measurement Age, height, and weight were gathered by patient self-report or from hospital charts. Number and type of comorbidities were captured using the Self-Administered Comorbidity Questionnaire. 38 All outcomes were collected using self-report questionnaires at baseline, 2 weeks, and 3 months by an independent person blinded to group assignment.

Primary Outcomes Primary outcomes consisted of a 4-item pain-intensity measure (P4 pain scale) and the Knee injury and Osteoarthritis Outcome Score (KOOS) pain and function in daily living subscales. The P4 pain scale consists of 4 numeric pain rating scales to evaluate pain in the morning, afternoon, evening, and with activity in the previous 2 days.39 Higher scores represent higher pain intensity. The P4 is a reliable measure and more sensitive to changes in pain than single-item numeric pain rating scales.40 The KOOS is a modification of the Western Ontario and McMaster Universities Osteoarthritis Index. The KOOS comprises 41 questions distributed among 5 different subscales. The pain and function subscales have 9 and 17 items, respectively, each scored on a 5-point scale. KOOS subscales are converted to a 0-to-100 scale, with higher scores indicating less pain and greater function. The KOOS has good psychometric properties1,12 and is commonly used to evaluate health status in knee OA.35

Secondary Outcomes Secondary outcomes included the KOOS subscales of knee symptoms (7 items), function in sport and recreation (5 items), and quality of life (4 items). KOOS subscales were converted to a 0-to-100 scale, with higher scores representing fewer symptoms, better function, and improved quality of life, respectively. Results for

Sample-size calculations assumed a medium effect (F = 0.25), because there were no previously published studies examining MDT assessment and subgrouping in patients with knee OA. At least a medium effect would be required to justify use of the treatment in the clinical setting, as is consistent with the lower limit of previous reports of exercise therapy effects.14 Three groups were considered in sample-size calculations, because planned subgroup analyses consisted of 3 groups. For α = .05, β = .20, 2 degrees of freedom, and an attrition rate of 15%, 60 patients in each of the 3 groups, for a total sample of 180 patients, were required.

Main Analysis: Exercise Intervention Versus Control Descriptive statistics were determined for patient characteristics and baseline outcomes. Two-way, mixed-model analyses of covariance (ANCOVAs) were performed for the primary and secondary outcomes to compare treatment (control versus exercise intervention) and time (2 weeks, 3 months) main effects and interaction effects after adjustment by the baseline scores.21 Multiple comparisons were performed, including the mean differences between groups, with 95% confidence intervals (CIs) and Bonferroni corrections, accounting for these multiple comparisons. All ANCOVA analyses were consistent with the intention-to-treat principle for patients who completed baseline measures. Missing 2-week and 3-month data were imputed using regression equations developed from complete data (predictors included baseline scores, group assignment, and age). To examine the strength of the intervention, effect sizes (d) with 95% CIs were determined and interpreted based on conventional effect sizes for small (d = 0.20), medium (d = 0.50), and large (d = 0.80) effects.36 Effect sizes were calcu-

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Patients meeting inclusion criteria recruited from orthopaedic clinic, n = 180

Randomized, n = 180

Allocated to intervention, n = 120 • Withdrew consent, n = 21

Allocated to control, n = 60 • Withdrew consent, n = 1

MDT assessment, n = 99

Designated to derangement group, n = 40 Lost to follow-up, n = 1 • Ill health, n = 1

Complete at 2 wk, n = 39 Lost to follow-up, n = 9 • Confounding intervention, n = 4 • Ill health, n = 2 • Personal reasons, n = 2 • Collection error, n = 1 Complete at 3 mo, n = 30

Designated to nonresponder group, n = 59

Lost to follow-up, n = 6 • Confounding intervention, n = 1 • Diagnostic error, n = 2 • Unable to contact, n = 1 • Personal reasons, n = 2

Lost to follow-up, n = 5 • Ill health, n = 1 • Unable to contact, n = 3 • Personal reasons, n = 1 Complete at 2 wk, n = 54

Complete at 2 wk, n = 53

Lost to follow-up, n = 5 • Confounding intervention, n = 4 • Personal reasons, n = 1

Complete at 3 mo, n = 49

Lost to follow-up, n = 8 • Confounding intervention, n = 6 • Unable to contact, n = 2

Complete at 3 mo, n = 45

FIGURE. CONSORT flow diagram. Abbreviation: MDT, Mechanical Diagnosis and Therapy.

lated separately at 2 weeks and 3 months, using contrasts from 1-way ANCOVAs, with adjustment for baseline scores and unequal sample sizes, and were consistent with the intention-to-treat principle: 2t , d= dfwithin



where t is the t value of the contrasts and dfwithin is the associated degrees of freedom.36 Individual patient change was assessed by examining percentage of patients in each group who had improve-

ments equal to or greater than the minimal detectable change at 90% confidence limits (MDC90) for KOOS pain (standard deviation, 18; intraclass correlation coefficient = 0.90; MDC90 = 13) and KOOS function (standard deviation, 16; intraclass correlation coefficient = 0.89; MDC90 = 12) scores; MDC90 values were calculated from previous study data.35 This was performed separately at 2 weeks and 3 months, with only complete patient data at those time points (imputed data from the intention-to-treat analysis were not included). No similar published data

to determine P4 pain scale MDC90 in patients with knee OA were available.

Subgroup Analyses The exercise intervention group was divided into MDT derangement and MDT nonresponder subgroups for further exploratory analyses. Independent t tests were used to compare baseline characteristics and variables between subgroups. Two-way, mixed-model ANCOVAs were used to compare primary outcomes between the MDT derangement and MDT nonresponder subgroups over time, after

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Patient Characteristics and Baseline Primary Outcomes*

TABLE 1

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Exercise Intervention Subgroup† Variable Age, y

Control (n = 59)

Exercise Intervention (n = 99)

MDT Nonresponder (n = 59)

MDT Derangement (n = 40)

64  11

66  10

64  9

68  10

Mass, kg‡

85.6  16.3

89.6  22.1

90.5  23.8

88.2  19.5

Height, m‡

1.67  0.10

1.69  0.10

1.68  0.10

1.70  0.10

BMI, kg/m2‡

30.7  5.3

31.4  7.7

32.0  8.9

30.6  5.4

34 (60)

55 (56)

33 (56)

22 (55)

3

3

3

3

P4 pain scale

23  8

21  10

22  9

19  10

KOOS pain

46  17

51  17

49  17

54  17

KOOS function

51  18

56  17

54  18

58  16

Sex (women), n (%) Median comorbidities‡

Abbreviations: BMI, body mass index; KOOS, Knee injury and Osteoarthritis Outcome Score; MDT, Mechanical Diagnosis and Therapy. *Values are mean  SD unless otherwise indicated. † MDT nonresponder and MDT derangement groups are subgroups of the exercise intervention group. ‡ Comorbidity data were not available for 5 patients. Mass, height, and BMI data were not available for 15 patients.

adjustment for baseline scores. Bonferroni corrections accounted for multiple comparisons. Mean differences and effect sizes (d) with 95% CIs of the control group and exercise intervention subgroups (MDT nonresponders, MDT derangement) were compared at 2 weeks and 3 months, after adjustment for baseline scores. The majority of analyses were conducted with SPSS Version 20 (SPSS Inc, Chicago, IL). Effect-size CIs were calculated with a custom program created in MATLAB Version 7.14 (The MathWorks, Inc, Natick, MA). Analysis of 1-year data was originally planned; however, a large number of patients proceeded to TKR prior to this time point, so 1-year outcomes were not included in the analysis.

RESULTS

B

etween November 2009 and April 2012, 180 patients met the inclusion criteria and were recruited. Twenty-two patients subsequently withdrew their consent after randomization (21 from the exercise intervention group and 1 from the control group). These patients, after being informed more ex-

tensively, felt that they were unable to fulfill the study commitment or were not available to schedule the baseline visit. These 22 patients provided no baseline data and were not included in the analysis. Six patients did not provide complete baseline data for the KOOS subscales (1 patient for KOOS symptoms, 1 for KOOS pain, 1 for KOOS function, and 3 for KOOS sport). A participant flow diagram (FIGURE) details the number and explanation for those lost to follow-up. All of the missing data at 2 weeks and 3 months were accounted for in the intention-totreat analysis.

Main Analysis: Exercise Intervention Versus Control There were no notable differences (P>.05) between the exercise intervention and control groups at baseline (TABLE 1). Outcome scores and the adjusted mean differences between these groups at the 2-week and 3-month follow-ups are provided in TABLE 2. For the P4 pain scale, a significant treatment main effect (P

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