The posterior ulna medial approach to the elbow: a cadaveric anatomical study of exposure of the coronoid and posteromedial collateral ligament.

BACKGROUND: This study aimed to describe the posterior ulna medial approach (PUMA) that permits exposure and repair of the anteromedial coronoid facet and posterior bundle of the medial collateral ligament (pMCL) in posteromedial rotatory instability (PMRI). Varus PMRI of the elbow disrupts key stabilizers, the anteromedial coronoid facet, the lateral ligament complex, and the posterior band of the medial collateral ligament, often requiring surgical stabilization. Although the pMCL is pivotal for stability, a reproducible posterior approach allowing for its direct repair has not been well described. METHODS: Six freshly unfrozen upper limbs were dissected using the PUMA. We assessed the exposure, involvement with the ulnar nerve, and feasibility of pMCL repair. Surgeons completed online pre- and post-cadaveric questionnaires assessing the approach's utility. RESULTS: The PUMA consistently exposed the pMCL without detaching the primary origin of the flexor pronator, violating the anterior MCL, or requiring transposition of the ulnar nerve. It enabled simulated repair of the pMCL and, when required, the medial collateral ligament, and fixation of the anteromedial coronoid. Neurovascular structures remained protected throughout the procedure. CONCLUSIONS: The PUMA offers anatomical access to the pMCL and adjacent medial elbow structures in a cadaveric setting, demonstrating feasibility for repair in selected PMRI patterns. Level of evidence: Anatomical study.