Extracorporeal shockwave therapy improves pain and function in subjects with knee osteoarthritis: A systematic review and meta-analysis of randomized clinical trials

Objective: To examine the safety and effectiveness of extracorporeal shockwave therapy (ESWT) for reducing pain and improving functionality in people with knee osteoarthritis (KOA). Methods: The Cochrane Library, PubMed, CINAHL, Physiotherapy Evidence Database (PEDro) and Google Scholar were systematically searched for randomized trials published up to September 30th of 2019. The main outcome measures to evaluate the treatment effect were pain, as reported on a visual analogue scale (VAS), and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Secondary outcome measures were the range of motion (ROM) and walking tests. A quantitative analysis was conducted using the inverse variance method and the random effects model. Results: Fourteen studies were included (n = 782 participants and 877 knees). Moderate quality of evidence showed that ESWT causes a decrease on the pain VAS [mean difference (MD) = 1.7 cm; confidence interval (CI) 95%: 1.1-2.3] and WOMAC (MD = 13.9 points; CI 95%: 6.9-20.8). The effect of ESWT using medium energetic density was greater than with low or high density in the WOMAC (Chi(2) = 9.8, p = 0.002) and bordered statistical significance on the VAS (Chi(2) = 3.8, p = 0.05). Very low quality of evidence showed that ESWT causes moderate improvement in the knee ROM (MD = 17.5 degrees; CI 95%: 9.4-25.5) and walking test [standardized mean difference (SMD) = 0.58; CI 95%: 0.35-0.81]. Conclusions: ESWT is an effective treatment for improving pain and functionality in patients with KOA in the short term with few minor side effects. Further clinical trials should include longer follow-up periods and be designed to lower the risk of bias.