1438 - A Novel Approach to Facet Joint Denervation Targeting the Sub-mammillary Fossa: A Case Study

Case Diagnosis: Facetogenic low back pain

Case Description: This is a case of a 56 year old male presenting with axial low back pain secondary to facet joint dysfunction with image findings of pronounced facet hypertrophy. The patient had a prior LMBB using a traditional approach with < 50% relief in pain. Given his continued concordant facet mediated pain, a decision was made to pursue repeat LMBB/RFA using a novel approach to test for improved neural coverage and pain relief, targeting the medial branch within the sub-mammillary fossa. Modified fluoroscopic technique was utilized to place needles along the sub-mammillary fossa located inferior and medial to the mamillo-accessory notch. 0.5mL of 0.5% Bupivacaine was injected at each site. On follow up, patient reported > 80% resolution of pain for the duration of anesthetic. This result was reproduced successfully with the second MBB. Patient was scheduled for high temperature RFA utilizing this approach.

Discussions: Lumbar medial branch (LMB) radiofrequency ablation (RFA) is a widely used treatment for facetogenic low back pain, but outcomes can vary due to technical and anatomical challenges. Recent studies have identified the sub-mammillary fossa as a novel anatomical target that may enhance MB capture and improve consistency in pain relief. The sub-mammillary fossa offers a unique and complementary target to traditional approaches, making it especially useful in cases of severe scoliosis or pronounced facet hypertrophy. In this case, the patient demonstrated improved efficacy with LMBB using the novel approach and may experience improved neural coverage during RFA.

Conclusions: This case highlights the clinical applicability of the sub-mammillary fossa as an alternative or adjunctive site for MB targeting, especially in anatomically challenging presentations. Further clinical studies are warranted to validate long-term outcomes and to refine fluoroscopic techniques for broader adoption in interventional pain practice.