Lower trapezius transfer to infraspinatus in cases of sequelae of obstetric brachial plexus injury.

Background: Deficient shoulder function is a common and exhausting issue in children with obstetric brachial plexus injuries. Even with functioning elbow, wrist, and fingers, upper limb function is markedly disabled by limited shoulder abduction external rotation. Lower trapezius transfer carries many advantages; simple and safe technique, same line of pull as donor; reliable nerve supply (extraplexal from spinal accessory nerve), and not acting on rotation of the shoulder, mostly it will not adversely affect internal rotation range after the transfer. This study aims to evaluate the role of isolated lower trapezius transfer in reconstructing shoulder external rotation.

Materials And Methods: This prospective case series study included 20 patients with sequelae of obstetric brachial plexus injury lacking shoulder external rotation who underwent lower trapezius transfer to infraspinatus. In all cases, the lower trapezius muscle was the donor, and the recipient tendon was the Infraspinatus muscle. Shoulder range of motion, Modified Gilbert grading, and Mallet Classification were used to evaluate results.

Results: The mean age at the time of surgery was 4.5 years. The average increase in shoulder external rotation and abduction was 40⁰ and 42.5⁰ respectively, the modified Gilbert grading improved from a mean of 3.85 to 4.85 postoperative. Mallet classification improved from a mean of 3.5 preoperative to 4.8 postoperative. Improvement (Mallet classification of ≥ 4) was obtained in 18 cases (90%).

Conclusion: Isolated lower trapezius transfer is considered an effective option with promising results in cases of sequelae of obstetric brachial plexus injury for restoration of shoulder external rotation as well as abduction.