Distal Nerve Transfer for Opponensplasty in the Setting of High Median Nerve Injury: A Case Series

Background: High median nerve injury leads to an absence of thumb opposition and irreversible thenar atrophy. Currently, distal nerve transfer is a new option for opponensplasty. The superiority of nerve transfer over traditional tendon transfer is that in nerve transfer, all thenar muscles may be reinnervated and so thumb functions are fully achieved, while in tendon transfer, the goal is to reanimate the function of abductor pollicis brevis (APB). This study aims to describe the results of opponensplasty using distal nerve transfer. Materials and Methods: This article analyses the results of opponensplasty using the transfer of abductor digiti minimi (ADM) branch of the ulnar nerve to the recurrent branch of the median nerve. Clinical outcomes were assessed by objectively evaluating APB strength, degree of thumb opposition, and thenar muscle bulk. APB strength and degree of thumb opposition measured by Medical Research Council (MRC) and Kapandji scoring systems, respectively. Results: From 2016 to 2019, six patients with a mean age of 29.5 years (five males and one female) with high median nerve injury were considered for opponensplasty using nerve transfer. Clinical improvement, including APB strength regaining and thumb opposition, was achieved in all patients. Moreover, recovery of thenar atrophy was observed in five patients. Conclusion: In high median-nerve injury, early reconstructive intervention can prevent the thenar muscle atrophy and leads to prompt reinnervation and complete restoration of thenar function. ADM branch of the ulnar nerve is a superior donor for this purpose.