Analysis of effectiveness of therapeutic exercise for knee osteoarthritis and possible factors affecting outcome

Abstract

Background: There are numerous reports and evidences to suggest that exercise therapy is effective for knee osteoarthritis (knee OA). However, there is a lack of sufficient research concerning the factors influencing its application and effectiveness. The purposes of this study were to evaluate effects of the mode of treatment delivery on the improvement of symptoms in knee OA, and to analyze potential risk factors affecting improvement after exercise therapies.

Methods: The 209 women applicants diagnosed with knee OA were randomly allocated into either a group performing group exercise in a class or a group performing home exercise. The 90 min exercise program was performed under the guidance of physiotherapists as a group exercise therapy. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) of the subjects of both groups before and after intervention was compared to examine the effect of exercise therapy. In addition, body mass index, knee range of motion (ROM), the femorotibial angle from radiographs, OA severity from Kellgren-Lawrence grade, and meniscus abnormality and subchondral bone marrow lesions from MRI findings were statistically analyzed as factors that may affect exercise therapy.

Results: A significantly greater improvement in WOMAC was observed in the subjects of group exercise (81 subjects) as compared with the subjects of home exercise (122 subjects). There was a significantly high proportion of subjects with knee flexion contracture among the subjects participating in group exercise that showed only minor symptom improvement (p < 0.05). In addition, exercise therapy proved to be highly effective for subjects with limited quadriceps muscle strength (p < 0.05).

Conclusions: When prescribing exercise therapy for knee OA, evaluation of a subject's ROM and muscle strength is important in deciding whether to commence exercise therapy and what type of exercise therapy to apply; it is also important in predicting the effect of exercise therapy.