Shortwave diathermy for managing knee osteoarthritis: A systematic review with meta-analysis

Background Shortwave diathermy (SWD) is an important non-surgical treatment method for knee osteoarthritis (KOA), but the current research results on its clinical efficacy are inconsistent.Objectives The purpose of this systematic review was to evaluate the extent to which SWD produces clinically relevant improvements in KOA.Methods PubMed, Embase, Web of Science, and the Cochrane Library were searched up to April 1, 2026. Risk of bias and evidence certainty were assessed. Data synthesis and statistical testing were executed with Stata version 18.Results The final analysis encompassed 17 trials with an aggregate sample of 1,372 participants. Pre-post pooled analysis revealed SWD significantly improved pain (mean −2.13; 95% CI [−2.64, −1.62];p < .01), walking ability (mean −0.72; 95% CI [−1.07, −0.36];p < .01), physical function (mean −6.17; 95% CI [−10.06, −2.29];p < .01), and stiffness (mean −1.12; 95% CI [−1.48, −0.75];p < .01). Compared with conventional therapy, SWD provided superior pain relief (SMD −0.53; 95% CI [−0.98, −0.08]; p = .02), with comparable outcomes for walking ability, function, and stiffness. Ultrasound outperformed SWD in pain alleviation (SMD 0.28; 95% CI [0.05, 0.51]; p = .02), yet they did not differ statistically in walking ability, physical function, or stiffness. SWD outcomes were statistically comparable to electrotherapy for pain, physical function, and stiffness.Conclusion SWD appears to yield meaningful improvements in pain, walking ability, knee joint function, and stiffness. It does not outperform ultrasound or electrotherapy; however, SWD may provide greater pain relief than conventional therapy. Because some evidence is of very low certainty, definitive conclusions cannot be drawn, and further high-quality randomized trials with standardized protocols are needed.