Anomalous Courses of the Palmar Cutaneous Branch of the Median Nerve in Relation to the Flexor Carpi Radialis Tendon for ORIF of Distal Radius Fractures

Abstract

Background: The purpose of this study was to prospectively document the incidence of variations in the course of palmar cutaneous branch of the median nerve (PCBMN) that may increase the risk of injury to the nerve during the flexor carpi radialis (FCR) approach. We hypothesize that the incidence of anomalous branching of the PCBMN around the FCR sheath will be approximately 5%. Methods: All cases that met inclusion criteria between November 2013 and March 2018 were included. The operating surgeon made the final decision for operative intervention using the FCR approach. Each surgeon performed the standard FCR approach to the distal radius. The branching location from the median nerve, the relationship to the FCR sheath, and the course of the PCBMN were recorded. Results: In total, 101 distal radius fractures were included. The average branching point of PCBMN was 5.2 cm from the distal wrist crease (range = 3.3-9.0). There were 26 anomalous branching patterns of PCBMN. Nineteen (18.8%) crossed volar, dorsal, or ran within the FCR sheath. Six PCBMN were found within the FCR sheath, 1 penetrated the FCR sheath, 6 crossed volar to the FCR sheath, and 6 were dorsal to the FCR tendon sheath. When comparing the branching patterns of the PCBMN from the median nerve, 4 branched from the volar aspect, 2 branched from the dorsal aspect, and 1 branched from the ulnar aspect of the median nerve. Conclusions: Variation in the course of the PCBMN relative to the FCR sheath is more than previously thought and can be expected in approximately 18.8% of patients.