Therapeutic ultrasound for osteoarthritis of the knee

Therapeutic ultrasound is one of several physical therapy modalities suggested for the management of pain and loss of function due to OA.

To assess the effectiveness of therapeutic ultrasound therapy for treating OA.

We searched the Cochrane Musculoskeletal Group trials register, and MEDLINE, up to the end of December 2000, using the sensitive search strategy developed by the Cochrane Collaboration. The search was complemented with bibliography searching of the reference list of the trials retrieved from the electronic search. Key experts in the area were contacted for further published and unpublished articles.

All randomized controlled trials (RCTs) and controlled clinical trials (CCTs) comparing therapeutic ultrasound against placebo or another active intervention in patients with OA were selected.

Two reviewers determined the studies to be included based on inclusion and exclusion criteria (LB, VW). Data were independently abstracted by two reviewers (VW, LB), and checked by a third reviewer (BS) using a pre-developed adapted form for the OA sub-group of the Cochrane Musculoskeletal Group. The same two reviewers, using a validated scale, assessed the methodological quality of the RCTs and CCTs independently. OA outcome measures were extracted from the publications. The pooled analysis was performed using weighted mean differences (WMDs) for joint counts, pain, global and functional assessments. A chi-square test was used to assess heterogeneity among trials. Fixed effects models were used throughout and random effects for outcomes showing heterogeneity.

Three trials, including 294 patients with knee OA were included. Only one trial (n=74) compared therapeutic ultrasound to placebo. This trial showed no difference in range of motion, pain or gait velocity after 4 weeks of therapeutic ultrasound. Two trials compared therapeutic ultrasound to an active therapy (n=220). These trials showed no statistical difference between galvanic current or short wave diathermy for the outcomes of pain and patient-assessed improvement.

Ultrasound therapy appears to have no benefit over placebo or short wave diathermy for patients with knee OA. These conclusions are limited by the poor reporting of the characteristics of the device, of the population, of the OA,and therapeutic application of the ultrasound and low methodological quality of the trials included. No conclusions can be drawn about the use of ultrasound in smaller joints such as the wrists or hands.