Cooled Radiofrequency Ablation of the Genicular Nerves for Chronic Pain due to Knee Osteoarthritis: Six-Month Outcomes.

Objective: Determine outcomes of cooled radiofrequency ablation (C-RFA) of the genicular nerves for treatment of chronic knee pain due to osteoarthritis (OA). Design: Cross-sectional survey. Setting: Academic pain medicine center. Subjects: Consecutive patients with knee OA and 50% or greater pain relief following genicular nerve blocks who underwent genicular nerve C-RFA. Methods: Survey administration six or more months after C-RFA. Pain numeric rating scale (NRS), Medication Quantification Scale III (MQSIII), Patient Global Impression of Change (PGIC), and total knee arthroplasty (TKA) data were collected. Logistic regression was used to identify factors that predicted treatment success. Results: Thirty-three patients (52 discrete knees) met inclusion criteria. Thirty-five percent (95% confidence interval [CI] = 22-48) of procedures resulted in the combined outcome of 50% or greater reduction in NRS score, reduction of 3.4 or more points in MQSIII score, and PGIC score consistent with "very much improved/improved." Nineteen percent (95% CI = 10-33) of procedures resulted in complete pain relief. Greater duration of pain and greater than 80% pain relief from diagnostic blocks were identified as predictors of treatment success. The accuracy of the model was 0.88 (95% CI = 0.78-0.97, P  < 0.001). Conclusions: Genicular C-RFA demonstrated a success rate of 35% based on a robust combination of outcome measures, and 19% of procedures resulted in complete relief of pain at a minimum of six months of follow-up. Report of 80% or greater relief from diagnostic blocks and duration of pain of less than five years are associated with high accuracy in predicting treatment success. Further prospective study is needed to optimize the patient selection protocol and success rate of this procedure.