Anterior radial nerve transposition in humerus midshaft fractures: anatomic and clinical study

Purpose of the study Plate fixation of midshaft humerus fractures raises the risk of radial nerve injury. Anterior transposition of the radial nerve has been proposed as a possible solution but few reports have been published. The purpose of the present study was to validate the effect of transposition on the transposed radial nerve and its branches. Material and methods We conducted an anatomic study on 10 cadavers. The length of the radial nerve between 2 anatomic landmarks was determined before and after transposition and plate fixation. A clinical evaluation was performed four years after surgery in 6 patients with midshaft humerus fractures treated with plate fixation after radial nerve transposition. Results The anatomic study demonstrated a mean gain of 11 mm in the length of the radial nerve with no problem for the transposed nerve or its branches. Clinically, osteosynthesis was facilitated and tension on the nerve was reduced. Discussion These 2 complementary studies demonstrated the releasing effect of transposition on the radial nerve and the facilitated osteosynthesis reported by others. The benefit of transposition is particularly important when bone fixation is particularly difficult to achieve without risk of injuring the radial nerve. Transposition does however require an extensive dissection, and the patient must be informed. Conclusion The ideal indication for anterior transposition of the radial nerve is an oblique fracture of the mid-third to lower-third of the humeral shaft with radial palsy at onset. A certain degree of comminution facilitates the technique. Indications for this technique could however be widened to include cases of difficult osteosynthesis where the option to transpose the radial nerve is always a peroperative decision.