Efficacy of exercise intervention as determined by the McKenzie system of mechanical diagnosis and therapy for knee osteoarthritis: a randomized controlled trial

STUDY DESIGN: Randomized controlled trial. OBJECTIVES: To examine the efficacy of exercise 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. BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.