Feasibility of cooled radiofrequency ablation versus intra-articular hyaluronic acid for knee osteoarthritis in Singapore: a pilot study

INTRODUCTION: Knee osteoarthritis is a common and debilitating problem. Safe and effective nonoperative treatments with sustained outcomes are needed, especially for patients unsuitable for knee replacement. Cooled radiofrequency ablation (CRFA) and hyaluronic acid (HA) injection have demonstrated efficacy, but CRFA is less well studied in Asian populations. METHODS: In this prospective, open-label, randomised controlled pilot study, patients with chronic knee osteoarthritis seen at a single tertiary centre in Singapore, who had at least 50% pain reduction after a genicular nerve block, were allocated to undergo CRFA or receive a single 6 mL injection of HA. Visual Analogue Scale (VAS) for pain, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) knee scores, Knee Injury and Osteoarthritis Outcome Score (KOOS), EuroQol-5 Dimensions-5 Level and Global Perceived Effect were compared at 2 weeks, 1 month, 3 months and 6 months after treatment. RESULTS: Twelve participants underwent intervention (7 CRFA and 5 HA), and 11 completed follow-up to 6 months (7 CRFA and 4 HA). Responder rates at 6 months were 40.0% (95% confidence interval [CI] 11.8%-76.9%) for HA and 28.6% (95% CI 8.2%-64.1%) for CRFA. Over time, VAS, KOOS and WOMAC pain scores and GPE improved in both groups, with peak improvement at 1 month. Adverse events were generally minor and self-limiting. Intergroup differences were not statistically significant. CONCLUSION: Both interventions were safe and efficacious for knee osteoarthritis. Owing to the small sample size, the findings were preliminary and hypothesis-generating. Larger studies comparing CRFA with other interventions for knee osteoarthritis in the Singapore population are warranted.