Abstract No. 273 Cooled versus Standard Radiofrequency Ablation of the Medial Branch Nerves in the Management of Chronic Facetogenic Low Back Pain

Lumbar facetogenic back pain has been estimated as high as 45% of all chronic low back pain causes (range 15-45%).1 Radiofrequency ablation of the lumbar medial branches is a commonly performed treatment for this indication.2 The study objective was to compare effectiveness of cooled and standard radiofrequency ablation in the management of chronic lumbar facetogenic back pain. This prospective, multi-center, randomized study was registered on ClinicalTrials.gov (NCT04803149) on March 17, 2021. Participants were eligible if they had a positive response from dual medial branch blocks (MBB). Bilateral lumbar medial branch radiofrequency ablation was performed targeting the left and right L3 and L4 medial branches L5 dorsal ramus to treat the L4–L5 and L5–S1 facet joints (Fig 1) with either CRFA (17 gauge with a 4-mm active tip) or SRFA (20 gauge curved probe with a 10-mm active tip). Following treatment, follow-up visits were performed at months 1, 3, 6, 9 and 12. Endpoints included NRS, SF-36, EQ-5D-5L and the Oswestry Disability Index (ODI). The primary effectiveness endpoint was defined as the proportion of subjects whose back pain was reduced by ≥ 50% based on Usual NRS (average daily pain over the last 7 days) at 6 months. A sample size of 75 participants in each group (total of 150) would achieve 80% power. Due to difficulty in finding participants to meet inclusion criteria, enrollment ended early. A total of 74 participants were treated (37 in each cohort). Usual NRS scores for both cohorts are reported in Table 273.1. At 6 months in the CRFA group, 20 of 27 (74.1%) were responders and in the SRFA group, 22 of 34 (64.7%) (p = 0.0069 between groups). Both groups demonstrated a reduction in pain of greater than 2 points on NRS, from baseline to 6 months. The mean NRS at baseline for the CRFA group = 6.9 (+1.22) and at 6 months = 2.7 (+2.88), a 4.2 drop in pain score with 27 participants reporting. The mean NRS at baseline for the SRFA group = 6.8 (+0.83) and at 6 months = 3.4 (+2.29), a 3.4 drop in score, with 34 participants reporting (p = 0.1234 between groups). Secondary endpoints reported in Table 273.2 show the mean score and mean change from baseline for secondary endpoints SF-36 (Physical Function Domain), ODI, EQ-5D-5L Index Score and GPE for both cohorts. A single treatment of radiofrequency ablation of the lumbar facetogenic joints improves a patient's pain and function. This stands in contrast to the MINT trials,3 suggesting that appropriately selected patients, combined with widely adopted treatment protocols, result in clinically significant improvements for this patient popular.