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

This study determined the clinical efficacy of extracorporeal shockwave therapy and the predictors of its efficacy for knee osteoarthritis.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.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.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 (I2) = 62%), pain reduction (standardized mean difference (SMD) -2.02, 95% CI -2.38 to -1.67, P < 0.00001; I2 = 95%), and Western Ontario and McMaster Universities Osteoarthritis Index function outcome (SMD -2.71, 95% CI -3.50 to -1.92, P < 0.00001; I2 = 97%). Follow-up duration and energy flux density were independent significant predictors of shockwave efficacy.Shockwave therapy is beneficial for knee osteoarthritis. Shockwave dosage, particularly the energy level and intervention duration, may have different contributions to treatment efficacy.