Abstract
OBJECTIVE: To assess the dose-related effects of radial extracorporeal shock wave therapy on pain alleviation in knee osteoarthritis. METHODS: With the use of a 2?×?2 factorial randomized controlled design, 89 patients diagnosed with knee osteoarthritis were assigned to 1 of 4 treatment groups, which varied in terms of shock intensity (0.12 mJ/mm2, lower density, or 0.24 mJ/mm2, higher density) and shock number (2,000 impulses or 4,000 impulses), or to a placebo control. Each group received 4 sessions of radial extracorporeal shock wave therapy, one week apart. The primary outcome was pain intensity measured on a visual analogue scale, and the secondary outcome was the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score. Assessments were performed at baseline, after each session, and at 4-week follow-up. RESULTS: Two-way repeated-measures analysis of variance revealed a significant effect on the Pain score for intensity (p<0.001), with no effect for number (p=0.467) or the intensity?number interaction (p=0.536). Similar results were obtained for the WOMAC scores, except for an association between number and WOMAC score (p=0.036). At the 4-week follow-up, all treatment groups showed greater reductions in the Pain and WOMAC scores than the control group. In addition, scores decreased more at higher densities of shock intensity than at lower densities, while there was no significant difference between the 2,000- and 4,000-shock conditions. CONCLUSION: Moderate-intensity radial extracorporeal shock wave therapy was effective, and a higher density might be more efficacious in alleviating pain in knee osteoarthritis.