Outcomes of Botulinum Toxin Injection for Shoulder Internal Rotation Contractures in Infants with Brachial Plexus Birth Injury.

[PURPOSE] Shoulder internal rotation contractures (IRC) are common sequela of brachial plexus birth injuries (BPBI). Botulinum toxin A (BTX-A) injection into targeted muscles has been described to facilitate functional improvement at the shoulder joint and prevent glenohumeral dysplasia. The purpose of this study was to assess the outcomes of BTX-A injections on shoulder IRC in children with BPBI.

[METHODS] We conducted a retrospective analysis of 47 children with shoulder IRC due to BPBI, who were treated with BTX-A. Shoulder passive external rotation in adduction and Active Movement Scale external rotation scores were recorded before and after BTX-A injection. We also recorded the number of children who underwent secondary surgical balancing procedures to improve shoulder motion after BTX-A injection.

[RESULTS] Mean age at the time of injection was 12 months (range, 5-23 months). Subjects demonstrated a significant increase in passive external rotation of 46° (range, 10° to 90) at 4 months; an average improvement of 18° (range, -30° to 80°) persisted at 11 months after injection. A total of 28 patients (60%) underwent subsequent external rotation tendon transfer. At 5-year follow-up, 7 patients (15%) had adequate functional shoulder range of motion and did not undergo external rotation tendon transfer.

[CONCLUSIONS] Botulinum toxin A injections result in improvement in IRC due to BPBI, which is sustained beyond the expected half-life of 3 months. As many as 15% of patients who have this treatment avoid external rotation tendon transfer.

[TYPE OF STUDY/LEVEL OF EVIDENCE] Diagnostic IV.