Effects of repetitive shortwave diathermy for reducing synovitis in patients with knee osteoarthritis: an ultrasonographic study.

BACKGROUND AND PURPOSE Shortwave (SW) diathermy can be used to improve vascular circulation and reduce inflammation and pain for patients with osteoarthritis. However, reduction in synovial inflammation has never been explored. The purpose of this study was to investigate whether repetitive SW diathermy, using ultrasonographic examination, could reduce synovitis in patients with knee osteoarthritis. SUBJECTS AND METHODS Thirty subjects with 44 osteoarthritic knees participated in this study. Eleven subjects received SW, and 10 subjects received SW and nonsteroidal anti-inflammatory drugs. Nine subjects received no treatment and served as a control group. Synovial sac thickness superior, medial, and lateral to the patella was measured using ultrasonography. The sum of these 3 measurements was taken as the total synovial sac thickness. Subjects in the treatment groups underwent ultrasonographic examination before and after 10, 20, and 30 treatments, whereas control subjects underwent ultrasonographic examination before the experiment and then once every 2 or 3 weeks for a total of 3 follow-up measurements. RESULTS After 10 SW diathermy treatments, the total synovial sac thickness in both treatment groups was significantly less than the initial thickness, and the synovial sac continued to become significantly thinner with 20 sessions of treatment. These observations were not made in the control subjects. DISCUSSION AND CONCLUSION The results indicate that SW diathermy in patients with knee osteoarthritis can significantly reduce both synovial thickness and knee pain. Such reductions of synovial sac thickness and pain index continue over treatment sessions.