Background Medial branch blocks (MBBs) and intra-articular (IA) facet joint injections are both used to diagnose facet joint pain and are presumed to be equivalent. No study has sought to determine which has a better prognostic value before radiofrequency (RF) denervation.
Methods A case-control study was performed at 4 institutions in which RF denervation outcomes in patients who obtained 50% or more pain relief from either MBB (n = 212) or IA injections (n = 212) were compared. “Control” patients (MBB) were matched to “cases” by treating physician, last name, and date of treatments. During data mining, 87 patients were identified who underwent RF ablation after receiving both IA injections and MBB and were used for secondary analyses.
Results A total of 70.3% of MBB patients experienced 50% or more pain relief at the 3-month follow-up versus 60.8% in those who underwent IA injections (P = 0.041). In multivariable analysis, undergoing MBB was associated with RF treatment success (odds ratio [OR], 1.57; 95% confidence interval [95% CI], 1.0–2.39; P = 0.036), whereas opioid use (OR, 0.52; 95% CI, 0.34–0.79; P = 0.002) and previous back surgery (OR, 0.60; 95% CI, 0.38–0.95; P = 0.028) were associated with treatment failure. No significant differences were noted between MBB alone and combination treatment or single versus multiple blocks. In the secondary multivariable analysis including the combination IA + MBB group, MBB alone was again independently associated with an RF ablation treatment success (OR, 1.73; 95% CI, 1.12–2.67; P = 0.014).
Conclusions When used as a prognostic tool before lumbar facet radiofrequency, MBB may be associated with a higher success rate than IA injections. Our results should be confirmed by large, prospective, randomized studies.
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S.P.C. is a consultant for Semnur Pharmaceuticals, Mountain View, CA, and serves on the Advisory Board of Kimberly Clark, Roswell, GA. All other authors declare no conflict of interest. C.M.B. receives research funding from Neuros Medical, Willoughby, OH.
The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense.
This work was funded in part by a Congressional Grant from the Center for Rehabilitation Sciences Research, Uniformed Services University of the Health Sciences, Bethesda, MD (SAP Grant No. 111726).