No additional benefit of shortwave diathermy over exercise program for knee osteoarthritis in peri-/post-menopausal women: an equivalence trial

Objective: To evaluate the benefit of shortwave diathermy (SWD) supplemented to an exercise program for knee osteoarthritis (OA) in peri-/post-menopausal women. Methods: A double-blind randomized placebo-controlled equivalence trial was conducted in a university hospital. Participants including 113 women aged 50-85 years with primary knee OA were instructed to do regular quadriceps exercise, and randomized to control (n = 60) and treatment (n = 53) groups receiving sham SWD and therapeutic SWD, respectively. The treatment being evaluated was continuous SWD, 20 min/session, 3 sessions/week for 3 weeks. The outcomes including Thai Western Ontario and McMaster Universities OA (WOMAC) index, 100-m walking speed, stair ascent-and-descent time, global assessment, patient's satisfaction, and adverse events were assessed at baseline and end of treatment. Results: At the end of treatment, both groups had trivial but statistical improvement in all outcomes. Intention-to-treat analysis showed no statistically significant difference between the two groups in all outcomes. Per protocol analysis demonstrated the equivalence in Thai WOMAC total score, as the 95% confidence interval of difference (-0.62, 0.92) was within confidence limits of ±1 cm. Conclusion: The addition of SWD to an exercise program for knee OA in peri-/post-menopausal women is not superior to the exercise program alone.