Effectiveness of continuous versus pulsed short-wave diathermy in the management of knee osteoarthritis: A randomized pilot study

BACKGROUND: Short-wave diathermy (SWD) is an electrotherapeutic modality used in the conservative treatment of knee osteoarthritis (KOA). Electromagnetic radiation delivered in continuous (cSWD) or pulse (pSWD) mode provides a deep heating effect on tissues. There is no consensus on outcomes of treatment with cSWD versus pSWD in KOA. The aim of this study was to compare the effects of cSWD versus pSWD on pain, functionality and walking distance in KOA. METHODS: 34 female patients aged 49-65 with KOA were randomized into two groups. A total of 27 patients completed the study. One group (n=11) was treated with cSWD, the other (n=16) with pSWD for three weeks. Patients were assessed before, after and at one month post therapy. Outcome measures included visual analogue scale (VAS) for knee pain, Western Ontario and Mcmaster University Osteoarthritis Index (WOMAC) and a six-minute walking test (6MWT). RESULTS: Based on the minimal clinically important improvement (MCII), there was a reduction in VAS and WOMAC scores in both cSWD and pSWD groups post treatment (-37.3mm, 31.2mm respectively for VAS and 26%, 23% respectively for WOMAC) and at one month post treatment. There was no difference in pre and post treatment VAS for pain, WOMAC or 6MWT scores between the two groups. There was a small post treatment effect size on between- group 6MWT scores (Cohen’s d: 0.238). CONCLUSION: Both treatment options appear to be efficacious in reducing pain and improving functionality in KOA. There was no between-group difference. A larger study must be conducted to consolidate these findings.