The 'teres major first' approach for deltoid reinnervation in brachial plexus injuries with shoulder fracture-dislocations.

Background: In upper brachial plexus (C5-C6) avulsion injuries, deltoid reinnervation via radial-to-axillary nerve transfer is standard. However, fracture-dislocations around the shoulder complicate surgical exposure due to fibrosis and distorted anatomy.

Methods: Fifteen male patients (mean age: 26.1 years) with C5-C6 avulsion injuries and concomitant shoulder fractures were treated between October 2019 and April 2022 using a modified posterior approach. The "teres major first" technique utilized the inferior border of the teres major muscle as a consistent landmark to identify and mobilize the long head triceps branch and anterior axillary nerve. A vertical slit in the teres major tendon improved access and allowed tension-free coaptation. All patients also received spinal accessory to suprascapular nerve transfers, and partial ulnar and/or median nerve transfers for elbow flexion restoration.

Results: All patients had fibrous adhesions in the quadrangular space, and 3 had distal axillary nerve injuries. The teres major landmark enabled safe dissection in all cases. Twelve of 15 patients achieved deltoid reinnervation with active shoulder abduction between 110° and 170° (mean 156°; MRC grade III-IV). Three patients (2 with proximal humerus fractures and 1 with lateral clavicle fracture with coracoclavicular disruption) showed limited recovery (70°-80° abduction). Triceps donor site weakness (MRC grade ≥3 in 14/15) was tolerated well, and full elbow flexion was restored in all patients. EMG evidence of reinnervation appeared by week 21 (deltoid) and week 23 (infraspinatus), with improvement in active shoulder abduction from week 27 onward.

Conclusion: The "teres major first" approach enables rapid and safe identification of target nerves in brachial plexus injuries complicated by shoulder fractures and dislocations. This technique minimizes dissection in fibrotic areas, ensures tension-free repair, and achieves reliable functional outcomes. However this study is limited by the relatively small sample size and a reduced statistical power.