Improving active shoulder external rotation in adults with brachial plexus birth injury and internal rotation contracture

Background: Brachial plexus birth injury (BPBI) can lead to significant shoulder dysfunction, particularly internal rotation contractures that limit active external rotation (aER). This study evaluates the feasibility and outcomes of subscapular tendon step lengthening and partial coracoid resection to improve aER in adults with BPBI with no previous surgical experience. To our knowledge, no previous studies have investigated this type of surgical assessment in adults with BPBI. Methods: A retrospective analysis was conducted on 17 adult patients with BPBI. Preoperative and postoperative assessments included shoulder range of motion, glenoid and humeral head morphology, and subjective patient-reported outcomes. Results: The surgical procedure resulted in improved aER in all patients, without loss of functional internal rotation. Increased glenoid retroversion was associated with lower aER gains, as confirmed by linear regression analysis demonstrating a significant negative correlation between glenoid retroversion and postoperative improvement. Out of 17 assessed patients, 15 reported that they still would have chosen to undergo surgery based on their outcomes. Conclusions: Subscapularis tendon step lengthening and partial coracoid resection might provide a viable surgical option for improving aER in adults with BPBI with preserved glenohumeral joint morphology and internal rotation contracture. Increased glenoid retroversion negatively correlates with external rotation improvements, highlighting the need for careful patient selection.