Efficacy of extracorporeal shock wave therapy for knee tendinopathies and other soft tissue disorders: A meta-analysis of randomized controlled trials

Background: Extracorporeal shock-wave therapy (ESWT), which can be divided into radial shock-wave therapy (RaSWT) and focused shock-wave therapy (FoSWT), has been widely used in clinical practice for managing orthopedic conditions. The aim of this study was to determine the clinical efficacy of ESWT for knee soft tissue disorders (KSTDs) and compare the efficacy of different shock-wave types, energy levels, and intervention durations. Methods: We performed a comprehensive search of online databases and search engines without restrictions on the publication year or language. We selected randomized controlled trials (RCTs) reporting the efficacy of ESWT for KSTDs and included them in a meta-analysis and risk of bias assessment. The pooled effect sizes of ESWT were estimated by computing odds ratios (ORs) with 95% confidence intervals (CIs) for the treatment success rate (TSR) and standardized mean differences (SMDs) with 95% CIs for pain reduction (i.e., the difference in pain relief, which was the change in pain from baseline to the end of RCTs between treatment and control groups) and for restoration of knee range of motion (ROM). Results: We included 19 RCTs, all of which were of high or medium methodological quality and had a Physiotherapy Evidence Database score of ≥5/10. In general, ESWT had overall significant effects on the TSR (OR: 3.36, 95% CI: 1.84-6.12, P < 0.0001), pain reduction (SMD: - 1.49, 95% CI: - 2.11 to - 0.87, P < 0.00001), and ROM restoration (SMD: 1.76, 95% CI: 1.43-2.09, P < 0.00001). Subgroup analyses revealed that FoSWT and RaSWT applied for a long period (≥1 month) had significant effects on pain reduction, with the corresponding SMDs being - 3.13 (95% CI: - 5.70 to - 0.56; P = 0.02) and - 1.80 (95% CI: - 2.52 to - 1.08; P < 0.00001), respectively. Low-energy FoSWT may have greater efficacy for the TSR than high-energy FoSWT, whereas the inverse result was observed for RaSWT. Conclusions: The ESWT exerts an overall effect on the TSR, pain reduction, and ROM restoration in patients with KSTDs. Shock-wave types and application levels have different contributions to treatment efficacy for KSTDs, which must be investigated further for optimizing these treatments in clinical practice.