Body Donor Feasibility Study of Triple Nerve Transfer for Elbow Flexion in Upper Brachial Plexus Injury

Following C5 and C6 brachial plexus injury there is loss of active elbow flexion. Nerve transfers from ulnar and median nerves have been reported for restoration of innervation to biceps and brachialis. However, fatigue of reinnervated elbow flexors remains a challenge. Double versus single fascicle transfer results are superior (MRC Grade 4 score 83% vs. 63.3%; p = 0.013), considering this we evaluate the feasibility of reinnervating a third muscle to support elbow flexion in terms of minimum reinnervation distance and surgical technique. This study explores the feasibility of nerve transfer to biceps, brachialis, as well as brachioradialis (BR) via a lateral cutaneous nerve of forearm (LCNF) in-situ interposition graft. Eight fresh frozen body donors, of mixed age range and gender, were dissected to measure baseline limb lengths, irrespective of bone circumference to determine: branching motor points for key muscles (biceps, brachialis, and BR) and measure donor nerve fascicle dissection lengths and calculate theoretical reinnervation distances from median nerve to biceps, ulnar nerve to brachialis via MSCN and to BR via the LCNF. The novel transfer from the ulnar nerve to BR using LCNF interposition graft was feasible in all eight limbs. The average fascicle dissection length of the median nerve was 14.63 mm (95% CI: 12.4-16.9) and for the ulnar nerve was 17.5 mm (95% CI: 13.9-21.0). Average theoretical reinnervation distance for BR was 94.13 mm (±23.21, R: 70-145, 95% CI: 77.35-110.90) equivalent to 3 months for reinnervation. With the biceps, reinnervation was 23.0 mm (±3.46, R: 15-35, 95% CI: 17.38-26.82) approximately 4 weeks and was 35.0 mm (±16.23, R: 9-55, 95% CI: 25.5-47.39) or approximately 5 weeks for brachialis, not accounting for latency or intramuscular axon regeneration distances from the motor point. Nerve transfer reinnervation of the BR through a LCNF in-situ graft is feasible with acceptable reinnervation distances. Clinical adoption of this modification to the traditional Oberlin nerve transfer could provide a way of improving elbow flexion strength and endurance through providing more reinnervated muscle mass, with the inclusion of BR.