The goal of this study was to quantify the response of individuals with and without knee osteoarthritis (OA) to a single session of manual physical therapy. The intervention was comprised primarily of joint mobilization techniques, supplemented by exercises, aiming to improve knee extension. Background While manual therapy is beneficial to patients with knee OA, there is not much research quantifying the effects of a manual therapy treatment session on either motion or stiffness of osteoarthritic and normal knees. The study included 5 participants with knee OA and 5 age-, gender-, and body mass index-matched healthy volunteers. Knee extension motion and stiffness were measured with videofluoroscopy prior to and following a 30-minute manual therapy treatment session. Analysis of variance and intraclass correlation coefficients were used to analyze the data. Participants with knee OA had restricted knee extension range of motion at baseline, in contrast to the participants with normal knees, who had full knee extension. After the therapy session, there was a significant increase in knee motion in participants with knee OA (P = .004) but not in those with normal knees (P = .201). For stiffness data, there was no main effect for time (P = .903) or load (P = .274), but there was a main effect of group (P = .012), with the participants with healthy knees having greater stiffness than those with knee OA.
This study found end-range knee extension stiffness was greater in the participants with normal knees than those with knee OA. The combination of a lower level of stiffness and lack of motion in those with knee OA, which may suggest the potential for improvement, might explain why increased knee extension angle was observed after a single session of manual therapy in the participants with knee OA but not in those with normal knees. Videofluoroscopy of the knee appears reliable and relevant for future studies attempting to quantify the underlying mechanisms of manual therapy.