To assess the effectiveness of short-wave diathermy (SWD) treatment in the management of knee osteoarthritis (KOA) and to assess whether the effects are related to the induction of a thermal effect.
A systematic literature search was conducted in PubMed, CINAHL, PEDro, EMBASE, SPORTdiscus and Scholar Google. Included were trials that compared the use of SWD treatment in patients diagnosed with KOA with a control group (placebo SWD treatment or no intervention) and studies that used high-frequency electromagnetic energy (i.e., 27.12 MHz) with sufficient information regarding treatment dosage. Methodological quality of the included studies was assessed in accordance with the PEDro classification scale. A minimum of a 6/10 score was required for inclusion.
Seven studies were included in the final analysis. Treatment protocols (dosage, duration, number of treatments) varied extensively between studies. The meta-analysis of the studies with low mean power did not favour SWD treatment for pain reduction, while the results of studies employing some thermal effect were significant. No treatment effect on functional performance measures was determined.
This meta-analysis found small, significant effects on pain and muscle performance only when SWD evoked a local thermal sensation. However, the variability in the treatment protocols makes it difficult to draw definitive conclusions about the factors determining the effectiveness of SWD treatment. More research (using comparable protocols and outcome measurements) is needed to evaluate possible long-term effects of thermal SWD treatment and its cost effectiveness in patients with KOA.