Cooled radiofrequency ablation for patients with chronic postsurgical pain after total knee arthroplasty: Pilot clinical trial.

Introduction: Total knee arthroplasty (TKA) generally provides substantial and durable relief in end-stage knee osteoarthritis, yet a proportion of patients develops chronic postsurgical pain (CPSP). Conventional analgesics often fail to adequately address this condition. Cooled radiofrequency ablation (CRFA) has shown effectiveness in knee osteoarthritis, but its utility for patients with CPSP after TKA has not been investigated. This study aimed to report a phase I/IIa clinical trial regarding CRFA for patients with CPSP after TKA. Materials and methods: This prospective pilot study (jRCTs052230123) enrolled consecutive patients with CPSP between November 2023 and August 2025. Inclusion criteria included persistent pain ≥6 months after TKA, inadequate response to standard analgesics (NRS ≥5), and ≥50% pain reduction after diagnostic genicular nerve block. Following informed consent, participants underwent CRFA using the Coolief® system. The primary endpoint was the change in Numeric Rating Scale (NRS) pain score from baseline to 6 months. 2011 Knee Society Score (KSS) was also used for the efficacy evaluation. As for the safety evaluation, the occurrence and outcomes of any severe adverse events between the day of treatment and 6 months post-treatment were recorded. Results: Of 15 screened patients, 5 met all criteria and completed the study. CRFA resulted in a consistent reduction in pain intensity; however, the change in NRS scores did not reach statistical significance at 6 months. Responder analyses demonstrated that a substantial proportion of patients achieved clinically meaningful improvements at 6 months. Although the 2011 KSS showed a trend toward improvement, the change was not statistically significant. No adverse events or complications occurred. Conclusions: CRFA provided clinically meaningful pain relief without adverse events in patients with CPSP after TKA. These findings suggest that CRFA is a safe and potentially effective therapeutic option. Larger studies are needed to verify its clinical value.