Purpose: The radial nerve raises several problems during plate fixation of the mid third of the humerus because of its particular anatomic position. Translocation of the radial nerve has been proposed to distend the nerve. There have been few studies studying the feasibility of translocation. The purpose of our work was to validate the translocation effect on nerve distension and the status of the translocated radial nerve branches.

Materials and methods: We report an anatomic study of six cases. These patients had recent communitive fractures of the mid third of the humerus with immediate radial paralysis in three cases. The anterolateral approach was used to expose the nerves that were found to be continuous. Nerve translocation then plate fixation were achieved without neurolysis. The anatomic study was conducted on 15 cadavers: the distance between the last branch for the triceps and the first epicondylar motor branch was calculated in three positions: D0: mean distance in the anatomic position of the nerve; D1: mean distance of the nerve in the anatomic position with the plate; D2: mean distance after anterior translocation of the nerve. We provoked shaft fractures in the mid and lower third of the humerus and evaluated the sensorial and motor branches after translocation.

Results: In this clinical series, translocation was easily achieved in all cases without stretching the sensorial or motor branches. The three radial paralyses recovered in six months. There was not postoperative paralysis for the other cases. For the anatomy study, mean measurements for D0, D1, and D2 were 112, 116 and 106 mm, for a 10 mm gain between D2 and D1. The sensorial branch was stretched making the technique difficult in one case.

Discussion: The results of these two studies confirm the effect of radial nerve distension that facilitates fixation. It frees the posterior aspect of the humerus allowing access in case of nonunion. However, the translocation should be done without neurolysis of the radial nerve and after informed consent from the patient.

Conclusion: Anteromedial translocation of the radial nerve appears to be useful for fractures of the humerus. The ideal indication is an oblique fracture of the mid or lower third of the humeral shaft with immediate radial palsy. A certain degree of comminution facilitates the translocation.