Posterior Approach for Harvesting and Transferring an Ulnar Nerve Fascicle to Posterior Arm Muscles in C5-C7 Upper Brachial Plexus Injury: Surgical Technique and Case Series

BACKGROUND AND OBJECTIVES: Nerve transfers are crucial to upper brachial plexus injury reconstruction, and we describe a posterior approach for harvesting an ulnar nerve fascicle to reanimate posterior targets in C5-C7 injuries. METHODS: Twelve patients with traumatic upper brachial plexus injuries underwent staged nerve reconstruction between 2018 and 2025, including transfer of a selected ulnar nerve fascicle harvested through a posterior arm approach. The fascicle was transferred to the anterior branch of the axillary nerve or, in selected cases, to the motor branch of the long head of the triceps with outcomes assessed at ≥18 months. RESULTS: Nine patients completed follow-up, all achieving meaningful functional recovery (Medical Research Council M3-M4) of shoulder abduction or elbow extension without clinically significant ulnar donor morbidity. CONCLUSION: Posterior approach for ulnar nerve fascicle harvest is a safe, reproducible technique that expands donor options for deltoid and triceps reanimation in extended upper brachial plexus injuries.