Wrist Extension Reconstruction Using Distal Anterior Interosseous to Extensor Carpi Radialis Brevis Nerve Transfer in Brachial Plexus Injuries.

Purpose: Reconstruction of wrist extension in C5-C8 root brachial plexus injuries (BPIs) is challenging, because of limited nerve and tendon donors. The purpose of this study was to report outcomes relating to the pronator quadratus branch of the anterior interosseous nerve (AIN) to extensor carpi radialis brevis (ECRB) nerve transfer from three BP surgeons.

Methods: Ten patients with C5-C8 BPI underwent AIN to ECRB nerve transfer. The mean age of the patients was 30.5 ± 15.9 years. All patients were men. The mean time to nerve surgery following initial injury was 4.5 ± 1.2 months. In all patients, wrist extension was absent at baseline. All patients had a minimum follow-up of 12 months (mean: 28.1 months) after surgery.

Results: Seven of 10 patients achieved Medical Research Council (M) grading system 4 wrist extension. In these patients, mean time to M2 was 12.7 ± 10.1 months, and mean time to M4 was 19.9 ± 10.0 months. The three patients who did not achieve M4 wrist extension had double fascicular transfer and relied strongly on the "Oberlin effect" where wrist flexion was required to initiate and achieve antigravity elbow flexion. Additionally, the three patients who did not achieve M4 wrist extension also had longer recovery to achieve antigravity (M3) elbow flexion, all presenting with poorer ability to initiate and achieve elbow flexion independent of the Oberlin effect. None of the patients had loss of forearm pronation after AIN to ECRB nerve transfer.

Conclusions: The AIN to ECRB nerve transfer can effectively reconstruct wrist extension in BPI patients with C5-C8 root injuries. Single fascicular transfer with the ulnar nerve as a donor and avoidance of multiple muscle targets for reinnervation from the median nerve may result in more consistent recovery through this nerve transfer.

Type of study/level of evidence: Therapeutic V.