Dose-related effects of radial extracorporeal shock wave therapy for knee osteoarthritis: A randomized controlled trial

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.

Keywords: dose-response relationship; knee osteoarthritis; radial extracorporeal shock wave therapy.

Fig. 1

CONsolidated Standards of Reporting Trials (CONSORT) 2010 flow diagram. HD: higher density; LD: lower density.

Fig. 2

Changes from baseline to the 4-week follow-up in the visual analogue scale (VAS)-pain scores and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores across all groups (mean (standard deviation (SD)). (A) The mean VAS-pain score of all groups at baseline, after the 1st, 2nd, 3rd, and 4th sessions of treatment, and at the 4-week followup. (B) Variations in the mean WOMAC score across all groups. Group: LD/2,000, n = 19; LD/4,000, n = 19; HD/2,000, n = 19; HD/4,000, n = 18; Control group, n = 14. VAS: visual analogue scale; HD: higher density; LD: lower density; 4,000: 4,000 impulses; 2,000: 2,000 impulses.

Fig. 3

Comparisons of the visual analogue scale (VAS)-pain scores among treatments at the 4-week follow-up. Values are estimated marginal means (95% confidence interval; 95% CI) from 2-way repeated measures analysis of variance (ANOVA). *p < 0.05/3, post hoc Bonferroni-adjusted tests for multiple comparisons (k=3). HD: higher density; LD: lower density; 4,000: 4,000 impulses; 2,000: 2,000 impulses.

Fig. 4

Comparisons of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores among treatments at the 4-week follow-up. Values are estimated marginal means (95% confidence interval; 95% CI) from 2-way repeated measures analysis of variance (ANOVA). *p < 0.05/3, post hoc Bonferroni-adjusted tests for multiple comparisons (k = 3). HD: higher density; LD: lower density; 4,000: 4,000 impulses; 2,000: 2,000 impulses.