To assess the efficacy of ultrasound therapy (US) for decreasing pain and improving physical function, patient-perception of disease severity, and cartilage repair in people with knee osteoarthritis (OA). We conducted a systematic review (to February 2009) without language limits in MEDLINE, EMBASE, Cochrane Library, LILACS, MEDCARIB, CINAHL, PEDro, SPORT-discus, REHABDATA, and World Health Organization Clinical Trial Registry. We included randomized controlled trials of people with knee OA comparing the outcomes of interest for those receiving US with those receiving no US. Two reviewers independently selected studies, extracted relevant data and assessed quality. Pooled analyses were conducted using inverse-variance random effects models. Six small trials (378 patients) were included. US improves pain [Standardized Mean Difference (SMD) (95% confidence interval (CI))=-0.49 (-0.79, -0.18), P=0.002], and tends to improve self-reported physical function [SMD (CI)=-0.54 (-1.19, 0.12), P=0.11] along with walking performance [SMD (CI)=0.81 (-0.09, 1.72), P=0.08]. Results from two trials (128 patients), conducted by the same group, show a positive effect of US on pain [SMD (CI)=-0.77 (-1.15, -0.39), P<0.001], self-reported physical function [SMD (CI)=-1.25 (-1.69, -0.81), P<0.001], and walking performance [SMD (CI)=1.47 (1.06, 1.88), P<0.001] at 10 months after the intervention concluded. Heterogeneity observed between studies regarding the effect of US on pain was explained by US dose, mode and intensity. The quality of evidence supporting these effect estimates was rated as low. US could be efficacious for decreasing pain and may improve physical function in patients with knee OA. The findings of this review should be confirmed using methodologically rigorous and adequately powered clinical trials. Copyright 2010 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.
