A Yoga Strengthening Program Designed to Minimize the Knee Adduction Moment for Women with Knee Osteoarthritis: A Proof-Of-Principle Cohort Study

<div><p>People with knee osteoarthritis may benefit from exercise prescriptions that minimize knee loads in the frontal plane. The primary objective of this study was to determine whether a novel 12-week strengthening program designed to minimize exposure to the knee adduction moment (KAM) could improve symptoms and knee strength in women with symptomatic knee osteoarthritis. A secondary objective was to determine whether the program could improve mobility and fitness, and decrease peak KAM during gait. The tertiary objective was to evaluate the biomechanical characteristics of this yoga program. In particular, we compared the peak KAM during gait with that during yoga postures at baseline. We also compared lower limb normalized mean electromyography (EMG) amplitudes during yoga postures between baseline and follow-up. Primary measures included self-reported pain and physical function (Knee injury and Osteoarthritis Outcome Score) and knee strength (extensor and flexor torques). Secondary measures included mobility (six-minute walk, 30-second chair stand, stair climbing), fitness (submaximal cycle ergometer test), and clinical gait analysis using motion capture synchronized with electromyography and force measurement. Also, KAM and normalized mean EMG amplitudes were collected during yoga postures. Forty-five women over age 50 with symptomatic knee osteoarthritis, consistent with the American College of Rheumatology criteria, enrolled in our 12-week (3 sessions per week) program. Data from 38 were analyzed (six drop-outs; one lost to co-intervention). Participants experienced reduced pain (mean improvement 10.1–20.1 normalized to 100; p<0.001), increased knee extensor strength (mean improvement 0.01 Nm/kg; p = 0.004), and increased flexor strength (mean improvement 0.01 Nm/kg; p = 0.001) at follow-up compared to baseline. Participants improved mobility on the six-minute walk (mean improvement 37.7 m; p<0.001) and 30-second chair stand (mean improvement 1.3; p = 0.006) at follow-up compared to baseline. Fitness and peak KAM during gait were unchanged between baseline and follow-up. Average KAM during the yoga postures were lower than that of normal gait. Normalized mean EMG amplitudes during yoga postures were up to 31.0% of maximum but did not change between baseline and follow-up. In this cohort study, the yoga-based strengthening postures that elicit low KAMs improved knee symptoms and strength in women with knee OA following a 12 week program (3 sessions per week). The program also improved mobility, but did not improve fitness or reduce peak KAM during gait. The KAM during the yoga postures were lower than that of normal gait. Overall, the proposed program may be useful in improving pain, strength, and mobility in women with knee osteoarthritis. Clinical efficacy needs to be assessed using a randomized controlled trial design.</p><p>Trial Registration</p><p>ClinicalTrials.gov <a href="https://clinicaltrials.gov/ct2/show/NCT02146105?term=yoga+AND+osteoarthritis&rank=1" target="_blank">NCT02146105</a></p></div

Knee adduction moment (KAM) normalized to body mass during four yoga postures to strengthen knee muscles (Nm/kg).

<p>Biomechanical data are presented on n = 36 participants.</p

Yoga postures used in this lower limb strengthening program for knee osteoarthritis.

<p>The four postures investigated included the legs-together squat (top left), wide-legged squat (top right), and the lunge (bottom; the involved and uninvolved limb were analysed separately).</p

Mean (Standard Deviation) at baseline and follow-up for strength.

<p>Mean difference scores (follow-up–baseline) with 95% confidence intervals (CI) are also given, with positive change indicating improvement in self-reported outcomes and strength. Multiple comparisons for all outcome measures were corrected using a Bonferroni correction (new alpha level was set to p = 0.007). Significant comparisons are denoted with an asterisk (*).</p

Baseline characteristics of 38 women with symptomatic knee OA who completed the yoga intervention.

<p>Baseline characteristics of 38 women with symptomatic knee OA who completed the yoga intervention.</p

Levels 1 through 4 of the progressions in the yoga strengthening program.

<p>Please refer to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0136854#pone.0136854.s003" target="_blank">S1 Appendix</a> for further information on the exercises.</p

CONSORT diagram of participant flow through the recruitment, intervention allocation, and analysis of this study.

<p>CONSORT diagram of participant flow through the recruitment, intervention allocation, and analysis of this study.</p

Mean (Standard Deviation) at baseline and follow-up for self-reported physical function (Knee injury and Osteoarthritis Outcome Score).

<p>^ǂMissing due to incomplete questionnaire (n = 1)</p><p>^ɸMissing due to incomplete questionnaire (n = 3)</p><p>Mean difference scores (follow-up–baseline) with 95% confidence intervals (CI) are also given, with positive change indicating improvement in self-reported outcomes and strength. Multiple comparisons for all outcome measures were corrected using a Bonferroni correction (new alpha level was set to p = 0.007). Significant comparisons are denoted with an asterisk (*). ADL–Activities of Daily Living</p

Efficacy of a biomechanically-based yoga exercise program in knee osteoarthritis: A randomized controlled trial

<div><p>Objective</p><p>Certain exercises could overload the osteoarthritic knee. We developed an exercise program from yoga postures with a minimal knee adduction moment for knee osteoarthritis. The purpose was to compare the effectiveness of this biomechanically-based yoga exercise (YE), with traditional exercise (TE), and a no-exercise attention-equivalent control (NE) for improving pain, self-reported physical function and mobility performance in women with knee osteoarthritis.</p><p>Design</p><p>Single-blind, three-arm randomized controlled trial.</p><p>Setting</p><p>Community in Southwestern Ontario, Canada.</p><p>Participants</p><p>A convenience sample of 31 women with symptomatic knee osteoarthritis was recruited through rheumatology, orthopaedic and physiotherapy clinics, newspapers and word-of-mouth.</p><p>Interventions</p><p>Participants were stratified by disease severity and randomly allocated to one of three 12-week, supervised interventions. YE included biomechanically-based yoga exercises; TE included traditional leg strengthening on machines; and NE included meditation with no exercise. Participants were asked to attend three 1-hour group classes/sessions each week.</p><p>Measurements</p><p>Primary outcomes were pain, self-reported physical function and mobility performance. Secondary outcomes were knee strength, depression, and health-related quality of life. All were assessed by a blinded assessor at baseline and immediately following the intervention.</p><p>Results</p><p>The YE group demonstrated greater improvements in KOOS pain (mean difference of 22.9 [95% CI, 6.9 to 38.8; p = 0.003]), intermittent pain (mean difference of -19.6 [95% CI, -34.8 to -4.4; p = 0.009]) and self-reported physical function (mean difference of 17.2 [95% CI, 5.2 to 29.2; p = 0.003]) compared to NE. Improvements in these outcomes were similar between YE and TE. However, TE demonstrated a greater improvement in knee flexor strength compared to YE (mean difference of 0.1 [95% CI, 0.1 to 0.2]. Improvements from baseline to follow-up were present in quality of life score for YE and knee flexor strength for TE, while both also demonstrated improvements in mobility. No improvement in any outcome was present in NE.</p><p>Conclusions</p><p>The biomechanically-based yoga exercise program produced clinically meaningful improvements in pain, self-reported physical function and mobility in women with clinical knee OA compared to no exercise. While not statistically significant, improvements in these outcomes were larger than those elicited from the traditional exercise-based program. Though this may suggest that the yoga program may be more efficacious for knee OA, future research studying a larger sample is required.</p><p>Trial registration</p><p>ClinicalTrials.gov (<a href="https://clinicaltrials.gov/ct2/show/NCT02370667" target="_blank">NCT02370667</a>)</p></div