Clinical efficacy of extracorporeal shockwave therapy for knee osteoarthritis: a systematic review and meta-regression of randomized controlled trials

Objective: This study determined the clinical efficacy of extracorporeal shockwave therapy and the predictors of its efficacy for knee osteoarthritis. Data Sources: Electronic databases and search engines, namely MEDLINE, PubMed, EMBASE, Cochrane Library Database, Physiotherapy Evidence Database (PEDro), China Academic Journals Full-text Database, and Google Scholar, were searched until 5 March 2019, for randomized controlled trials without restrictions on language and publication year. Review Methods: Eligible trials and extracted data were identified by two independent investigators. The included articles were subjected to a meta-analysis and risk of bias assessment. Outcomes of interest included treatment success rate, pain, and physical function outcomes. A meta-regression analysis was performed to determine the predictors of treatment outcomes following shockwave therapy. Results: We included 50 trials (4844 patients) with a median (range) PEDro score of 6 (5-9). Meta-analyses results revealed an overall significant effect favoring shockwave therapy on the treatment success rate (odds ratio 3.22, 95% confidence interval (CI) 2.21-4.69, P < 0.00001; heterogeneity (I-2) = 62%), pain reduction (standardized mean difference (SMD) -2.02, 95% CI -2.38 to -1.67, P < 0.00001; I-2 = 95%), and Western Ontario and McMaster Universities Osteoarthritis Index function outcome (SMD -2.71, 95% CI -3.50 to -1.92, P < 0.00001; I-2 = 97%). Follow-up duration and energy flux density were independent significant predictors of shockwave efficacy. Conclusion: Shockwave therapy is beneficial for knee osteoarthritis. Shockwave dosage, particularly the energy level and intervention duration, may have different contributions to treatment efficacy.