Do Treatment Expectations Moderate the Effect of Manual Therapy in People With Knee Osteoarthritis? A Secondary Analysis of Randomized Clinical Trials.

OBJECTIVE: To investigate whether treatment expectations for joint mobilization or massage moderated the effect of manual therapy on pain outcomes in knee osteoarthritis (OA). DESIGN: Secondary moderation analysis of two 2×2 factorial randomized controlled trials. METHODS: Data were pooled from two trials that compared manual therapy and exercise to exercise alone in 375 people with knee OA. Before randomization, expectations were measured using a questionnaire that captured patients' views about the effect of common OA treatments to reduce knee pain using a 5-point Likert scale ranging from "completely disagree" to "completely agree." Responses regarding joint mobilization and massage were dichotomized into high and low expectations. The primary outcome was pain intensity at 9 weeks measured by the Numeric Pain Rating Scale. Linear regression models were used to test whether treatment expectations moderated manual therapy treatment response. Models were conducted separately for each of the two potential moderators (joint mobilization and massage) and adjusted for the same covariates associated with the outcomes of the original trials. RESULTS: Primary regression analysis showed no significant interaction effect between manual therapy and treatment expectations on pain outcomes at 9-weeks follow-up (mobilization: β = -0.17, 95% confidence interval [CI]: -0.90 to 0.56; massage: β = -0.26, 95% CI: -1.00 to 0.47). Sensitivity analyses showed similar findings. CONCLUSION: These exploratory findings indicated that treatment expectations did not moderate patient response to manual therapy for OA. JOSPT Open 2026;4(2):232-238. Epub 16 February 2026. doi:10.2519/josptopen.2026.0180.