Repeat Genicular Nerve Cooled Radiofrequency Ablation: Retained Efficacy or Diminishing Returns?

Introduction: Radiofrequency ablation (RFA) of the genicular nerve is an increasingly common treatment for chronic knee pain, refractory to conservative measures. However, RFA often provides significant but temporary relief, and patients return for repeat RFAs for the treatment of their pain. This study investigates the efficacy of repeat RFAs compared to the initial RFA for patients who receive repeat RFAs for chronic knee pain. Methods: This study is a retrospective chart review and analysis that was conducted between 2015 and 2023. Groups were determined by the number of RFA procedures that patients received, and a one-tailed ANOVA test was performed to assess the statistical significance of the initial RFA and the three repeat RFA groups. A one-way ANOVA was performed to analyze statistical differences between percent improvement, preoperative pain scores, and the duration of improvement using the visual analog scale (VAS). A p-value of statistical significance was set at p < 0.05. A paired two-tailed T-test was carried out, individually comparing the initial RFA to the three repeat groups for percent improvement. A paired t-test was also carried out to compare initial and first repeat RFAs for preoperative pain score and duration of improvement. Results: A total of 42 patients underwent repeat RFA procedures, with 8 receiving bilateral treatments, totaling 50 knees and 116 procedures. The original RFA group demonstrated a mean percent improvement of 75% ± 25% (mean ± SD) and a duration of improvement of 9.46 ± 5.45 months. The first repeat group had a mean percent improvement of 66% ± 29% and a duration of improvement of 8.77 ± 7.32 months. The second repeat group had a mean percent improvement of 67% ± 24% and a duration of improvement of 10.00 ± 2.45 months. The third repeat group had a mean percent improvement of 85% ± 20% and a duration of improvement of 4.00 months. ANOVA revealed no statistically significant differences among the groups in preoperative scores (p = 0.40), percent improvement (p = 0.25), or duration of improvement (p = 0.79). Paired t-tests showed a significant decrease in percent improvement in the first repeat RFA compared to the original RFA (p = 0.04), but no significant differences were observed in preoperative scores (p = 0.057) or duration of improvement (p = 0.175). No significant differences were found in percent improvement via paired T-test between the original RFA and the second (p = 0.75) or third repeats (p = 0.21). Conclusions: The repeat RFA of genicular nerves retains a clinically significant level of pain reduction for chronic knee pain. However, this study demonstrated decreased pain relief following the first repeat RFA compared to the initial RFA when analyzing individual knees sequentially via a paired T-test. An analysis of initial, first, second, and third repeat groups via ANOVA showed no difference in percent improvement, duration of pain relief, or preoperative pain scores.