Cooled Radiofrequency Ablation of the Genicular Nerves for Treatment of Chronic Knee Pain

Background: Chronic knee pain from conditions such as osteoarthritis (OA) is a significant problem in a growing and aging population. Cooled radiofrequency ablation (CRFA) is an emerging technique to treat chronic knee pain. There is significant literature noting the clinical outcomes of CRFA in anatomic locations including the peripheral joints and the lumbar spine. This retrospective study found significant improvements in Pain Disability Index (PDI) scores and Numerical Pain Rating Scale (NPRS) scores for patients with chronic knee pain who underwent cooled radiofrequency ablation (CRFA) therapy of the genicular nerves. Objectives: This retrospective study evaluated the effectiveness of CRFA in the general chronic knee pain population. Study Design: Retrospective electronic chart review. Setting: Outpatient non-profit practice. Methods: After institutional review board approval, we reviewed the data of 205 patients who had undergone cooled radiofrequency ablation therapy of the genicular nerves at a multiple-site pain practice between December 5, 2017 and September 4, 2019. The primary outcome was improvement in Pain Disability Index (PDI) scores. The secondary outcomes were pain scores, assessed by the Numerical Pain Rating Scale (NPRS), and opioid consumption, assessed by daily Morphine Equivalent Dose (MED). From the 205 patients who met inclusion criteria, there were 104 patients who had PDI scores both before and after the CRFA procedure that were collected in the appropriate time frame. For these 104 patients, the pain scores and opioid consumption before and after the CRFA procedure were also collected. The age of the 104 patients ranged from 21 to 89 years. There were 38 males and 66 females. Results: The mean PDI score before genicular nerve block and CRFA was 38.7, and the mean PDI score after CRFA was 26.5. After CRFA treatment, 67.38% of patients had a decrease in their PDI scores, 27.9% had no change, and 4.81% had an increase in their PDI scores. P-value <0.001 with 95% CI Median (-11, -7). The mean NPRS score before genicular nerve block and CRFA was 6.98, and the mean NPRS score after CRFA was 4.18. P-value <0.001 with 95% CI Median (-3, -2). The largest group of patients, 49% of patients, had a pain score reduction of 2.25 points, while the next largest group, 17.3% of patients, had a reduction of 0.75 points, followed by 12.5% of patients with a reduction of 3.75 points. When comparing Morphine Equivalent Dose (MED) before and after the CRFA procedure, 37.5% of patients were not on opioid medication at any time during the study; additionally, the MED did not change for the majority of patients (80.77%), while the MED decreased for 13.46% of patients and increased for 5.77% of patients. Mean MED before GNB and CRFA was 17.13 and 15.91 after CRFA. P=0.025 with 95% CI Median (0,0). No serious adverse events were reported. Limitations: Retrospective nature of the study. Conclusions: This study demonstrates the clinical effectiveness of CRFA for the treatment of chronic knee pain by improvements in PDI scores and NPRS scores for the majority of patients. Results from this study indicate that CRFA treatment provides significant pain relief and reduces the disability caused by chronic knee pain.