The effect of therapeutic ultrasound on pain and physical function in patients with knee osteoarthritis

Abstract

Osteoartritis (OA) is one of the most frequent causes of pain, loss of function and disability in adults. The prevalence of OA is expected to increase substantially in the future. Knee OA is the most common subset of OA. Therapeutic ultrasound (US) is one of several physical therapy modalities suggested for the management of pain and loss of function due to OA. The purpose of our study was to investigate the efficacy of US therapy in reducing pain and functional loss and improving the quality of life in patients with knee OA in comparison to sham US therapy. The study involved 62 patients. The patients were randomly divided into two groups. The patients in group 1 (n = 30) were administered 1 W/cm(2), 1 MHz continuous US, and the patients in group 2 (n = 32) were administered sham US. The US treatment was applied for 8 min to each knee, 16 min in total, 5 d a wk, for a total of 10 sessions during 2 wk. The patients were evaluated immediately after treatment and 1 mo after therapy according to the visual analog scale (VAS), night pain, range of motion, morning stiffness, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Lequesne and Short Form-36 (SF-36) scales and 6 min walking distance. Improvement in pain and joint functions was observed in both groups according to the evaluation immediately after treatment and at 1 mo after the therapy. According to the evaluation results immediately after treatment, there was significant improvement in all pain scales (VAS, WOMAC, Lequesne, SF-36), morning stiffness and 6 min walking distance in patients receiving real US treatment (p < 0.05), but only in some pain scales (VAS, WOMAC) and functions in the group receiving sham US (p < 0.05). Significantly better improvement was observed in some pain scales (SF-36), functions (WOMAC, SF-36) and 6 min walking distance in the real US group. At 1 mo after therapy, no significant difference was observed between groups except for improvement in night pain in the real US group. In conclusion, US therapy has been found to be effective in reducing pain and improving physical function in the short term, but this positive effect was not persistent in the long term. However, we believe that the results of our study may contribute to ongoing research for the treatment of patients with knee OA, and further systematic investigation on larger patient populations may delineate the role of US in knee OA treatment.