Variation of the palmar cutaneous branch of the median nerve identified within the tendon sheath of the flexor carpal radialis

Purpose: During volar plate fixation of distal radius fractures, we have encountered patients with an anomalous course of the palmar cutaneous branch (PCB) of the median nerve within the sheath of the flexor carpi radialis (FCR) tendon. The purpose of this study was to assess the frequency and location of variations of the PCB within the sheath of the FCR tendon.Methods: This retrospective study enrolled 83 patients who underwent volar locking plate fixations through a modified Henry approach for distal radius fractures from July 2018 to April 2020. When we encountered an anomalous PCB within the sheath of the FCR tendon, we documented the specific finding and location where the PCB entered the sheath of the FCR tendon.Results: There were nine patients (10.8%) who had an anomalous course of PCB penetrating the sheath of the FCR tendon. The average entering point of PCB into the sheath of the FCR tendon was 3.07 cm from the distal wrist crease (range, 2.5–3.6 cm).Conclusion: An anomalous course of the PCB entering the sheath of the FCR tendon was observed at a high frequency (10.8%). Care must be taken not to injure the PCB during a dissecting of the FCR sheath during a modified Henry approach for a distal radius fracture.