Distal median to ulnar nerve transfers to restore ulnar motor and sensory function within the hand: technical nuances

ULNAR NERVE INJURIES can be severely debilitating and result in weakness of wrist flexion, loss of hand intrinsic function, and ulnar-sided hand anesthesia. When these injuries produce a Sunderland fourth- or fifth-degree injury, surgical intervention is necessary for functional recovery. Traditional methods for restoring hand intrinsic function after ulnar nerve palsy include interposition nerve grafting for timely presentations or tendon transfers for either complex injuries or late presentations. Distal median to ulnar nerve transfer to restore ulnar intrinsic nerve muscle function was first performed in 1991. We continue to find it advantageous for recovery of ulnar intrinsic function in patients with proximal ulnar nerve injuries by significantly reducing denervation time and directing motor fibers into this critical motor distribution. Several case reports have been published discussing the concept behind this approach, but none have outlined the specific steps involved in this operation. As such, this article discusses our operative methodology behind the distal median to ulnar neurotization, which includes a Guyon canal release, identification of donor median and recipient ulnar nerve fascicular anatomy within the forearm, and an operative tutorial on proper technique for neurotization to restore both ulnar motor and sensory function. We present the technical nuances of the following nerve transfers to restore ulnar nerve function within the hand: anterior interosseous nerve to deep motor branch of ulnar nerve, third webspace sensory contribution of median nerve to volar sensory component of ulnar nerve, and end-to-side reinnervation of ulnar dorsal cutaneous to the remaining median sensory trunk.