Incidence of an Anomalous Course of the Palmar Cutaneous Branch of the Median Nerve During Volar Plate Fixation of Distal Radius Fractures

Abstract

Volar plating of distal radius fractures using an approach through the flexor carpi radialis (FCR) sheath is commonplace. The palmar cutaneous branch of the median nerve (PCB) is considered to run in a position adjacent to, but outside, the ulnar FCR sheath. Anatomic studies have not identified anatomic abnormalities relevant to volar plating. The purpose of this study was to determine the frequency of anomalous PCB branches entering the FCR sheath during volar plating. This observational study involved 10 attending hand surgeons during a 7-month period (July 2015-January 2016). Surgeons assessed, documented, and reported any PCB anomalies that were encountered during volar plating through a trans-FCR approach. There were 182 volar plates applied that made up the study group. There were 10 cases (5.5%) of anomalous PCBs entering the FCR sheath. In 4 cases, the PCB pierced the radial FCR sheath proximally, crossed beneath the tendon, and traveled distally on the ulnar side. In 4 other cases, the PCB entered the FCR sheath proximally on the ulnar or central aspect of the sheath and remained within the sheath, staying along the ulnar or dorsal side of the tendon. In 1 case, the PCB pierced the ulnar distal aspect of the sheath and split into 2 branches. In 1 case, the PCB ran within the sheath along the radial aspect of the FCR. Anomalies in the course of the PCB are more common than often considered. These variants are at risk during volar surgical approaches to the wrist that proceed through the FCR sheath. Although dissecting along the radial side of the FCR sheath may protect the PCB in most cases, care must be taken to identify anomalous branches (if present) and protect them during surgery.