Does Triceps Branch Transfer to the Whole of the Axillary Nerve Improve External Rotation in a Selected Group of Upper-Arm Brachial Plexus Patients?

Abstract

In upper brachial plexus injuries involving the C5–C6 roots, restoring shoulder abduction and external rotation remains a key objective of reconstructive nerve surgery. Conventional transfer of the long head triceps branch of the radial nerve to the anterior branch of the axillary nerve reliably reinnervates the deltoid, but its limitation lies in excluding the posterior axillary branch, leaving the teres minor denervated and often resulting in suboptimal recovery of external rotation. To address this limitation, we adopted a modified approach in which the long head triceps branch is transferred to the main axillary nerve trunk prior to its bifurcation, enabling simultaneous reinnervation of both anterior and posterior divisions. This technique was selectively applied in patients with C5–C6 injuries showing predominant C5 involvement—characterized by weakness of deltoid, supraspinatus, infraspinatus, and partially biceps, with preservation of C6-dominant radial nerve-innervated muscles such as brachioradialis. Anatomical considerations at the root level suggest that fascicles destined for the radial nerve are more posterior and resilient, making the donor branch a reliable source. Early clinical outcomes have been favorable. Patients demonstrated robust deltoid recovery comparable to or exceeding that achieved with the traditional technique. Notably, we observed a consistent improvement in active external rotation, suggesting effective reinnervation of the teres minor through inclusion of the posterior axillary branch. Transfer of the long head triceps branch to the main axillary nerve trunk appears to offer a more comprehensive reconstructive option for selected C5–C6 brachial plexus injuries. This modification enhances shoulder external rotation without compromising the reliability of deltoid reinnervation. Further study is warranted to validate these encouraging early results.