Localized hyperthermia induced by microwave diathermy in osteoarthritis of the knee: a randomized placebo-controlled double-blind clinical trial

Purpose: To investigate the effects of hyperthermia on knee osteoarthritis (OA) in a randomized placebo-controlled double-blind clinical trial. Methods: Sixty-three patients with clinical evidence and radiographic confirmation of knee OA (Kellgren and Lawrence grades II and III) were randomized to either three 30-min sessions of hyperthermia per week for 4 weeks were administered using a 433.92 MHZ microwave generator or receive placebo treatment (machine not turned on) for same number of sessions. The Western Ontario McMaster Universities (WOMAC) questionnaire and the Timed Up and Go test (TUGT), a performance-based measure of function, were obtained at baseline (week 0), at the end of treatment (week 4), and at final follow-up (week 16). Results: The treatment group showed a significant decrease in the overall WOMAC score and each of its components, and in the TGUG test between the beginning (week 0) and the end of treatment (week 4), as well as at final follow-up (week 16). In the placebo group, a significant fall was only visible in the pain subscore at week 4. However, the mean improvement was only 1 point and was lost at final follow-up (P = 0.332). There was a significant difference in pain -7.4 pre-post (P < 0.01), -8.1 pre-follow-up (P < 0.01); stiffness -4.6 pre-post (P < 0.01), -5.1 pre-follow-up (P < 0.01); activities daily living (ADL) -30.9 pre-post (P < 0.01), -33.2 pre-follow-up (P < 0.01); and WOMAC total score -43 pre-post (P < 0.01), -46.4 pre-follow-up (P < 0.01); and in TGUG test -2.4 pre-post (P < 0.01), -2.9 pre-follow-up (P < 0.01) between the treatment and placebo group over the whole length of the trial. Conclusions: A 433.92 MHz microwave hyperthermia regimen showed beneficial effects in patients with moderate knee OA to reduce pain and to improve their physical function. Level of evidence: I. © 2010 Springer-Verlag.