A description and outcome evaluation of sacrococcygeal joint radiofrequency neurotomy for treatment of chronic coccydynia - A dorsal approach.

Background: Coccydynia is a condition characterized by pain and tenderness in the coccyx region of the spine. Chronic coccydynia (≥3-months) management remains a clinical challenge. Radiofrequency neurotomy (RFN) targeting the sacrococcygeal joint (SCJ) and/or 1st intercoccygeal joint (ICJ) margins has emerged as an alternative, minimally invasive intervention for refractory coccydynia. Objective: The objective of this study was to evaluate the safety and effectiveness of an RFN technique targeting the dorsal aspect of SCJ and/or 1st ICJ for treatment of patients with chronic coccydynia. Methods: Retrospective analysis of prospective outcomes for patients with chronic coccydynia (≥3-months) who underwent RFN to dorsal SCJ and/or 1st ICJ between 2009 - 2023. RFN technique was a dorsal approach targeting the distal sacrum and proximal coccyx, which form the SCJ or 1st ICJ margins. Numerical rating scale (NRS) and Pain Disability Quality-of-Life Questionnaire-Spine (PDQQ-S) scores were completed pre- and 3-months post-RFN. Successful RFN was defined as ≥50% reduction or minimal clinical important difference (MCID) in PDQQ-S and NRS pain scores. The primary outcome measures were the proportion of patients achieving ≥50% reduction in NRS pain and PDDQ-S scores following primary and repeat RFN to SCJ and/or 1st ICJ. Secondary outcomes included the proportion of patients achieving MCID on NRS pain and PDQQ-S scores following RFN, as well as mean NRS and PDQQ-S scores pre- and 3-months post-RFN, and magnitude of improvement for patients following successful RFN procedures. Results: A total of 52 RFN procedures (n = 30 primary, and n = 22 repeat procedures) were performed on 30 patients (female = 25, male = 5, mean age 55.1 ± 13.0yrs). Ten patients (33.3%; 95% CI = 17.3-52.8) reported ≥50% pain reduction as measured by NRS pain and PDQQ-S scores following primary SCJ and/or 1st ICJ RFN at 3-months follow-up. Fifteen patients (50%; 95% CI = 31.3-68.7) reported MCID NRS pain reduction and 12 patients (40.0%; 95% CI = 22.7-59.4) reported MCID PDQQ-S scores at 3-months following primary RFN. The mean magnitude of improvement for patients with primary successful RFN, as defined as ≥50% reduction in either NRS pain or PDQQ-S scores, was 77.4% (±SD 21.4%) and 74.9% (±SD = 19.9%), respectively. Similarly, the mean magnitude of improvement for patients with successful RFN, as defined by MCID reduction in NRS pain or PDQQ-S scores, was 62.6% (±SD = 28.2%) and 69.3% (±SD = 22.3%), respectively. At 3-months follow-up, 14 patients (63.6%; 95% CI = 40.7-82.8) reported ≥50% pain reduction as measured by either NRS pain and PDQQ-S scores following repeat RFN. Nineteen patients (86.4%; 95% CI = 65.1-97.1) reported MCID NRS pain reduction and 16 patients (72.7%; 95% CI = 49.8-89.3) reported MCID PDQQ-S scores at 3-months following repeat RFN. Statistically significant differences were observed between pre- and post-RFN NRS pain and PDQQ-S scores (p < 0.005) in both primary and repeat procedures. Discussion/conclusion: This study represents an introductory step in evaluating the efficacy of a dorsal approach RFN technique targeting the SCJ and/or 1st ICJ as a treatment option for chronic coccydynia. Primary RFN demonstrated pain reduction and improvement in function at 3-months in 33.3% of patients. Several limitations remain, including heterogeneity in patient population, small sample size, and no control groups. Future detailed investigations include cadaveric studies to clarify sensory innervation and enhance reliability of our targets during RFN. Larger prospective studies of long-term outcomes, including comparison with control groups, are required to further evaluate the efficacy of our dorsal RFN approach.