Radial nerve injury is common in humeral shaft fractures and fails to recover spontaneously in 30% of cases. Few studies have evaluated predictors of recovery. The objectives of this study were to identify predictors of radial nerve palsy recovery and to assess the usefulness of surgical radial nerve exploration in patients with preoperative radial nerve palsy.

Factors predicting the outcome of radial nerve palsy can be identified.

Of 373 patients with humeral shaft fractures between 2005 and 2012, 43 had radial nerve palsy, including 23 who were lost to follow-up and 17 who were evaluated retrospectively at a mean of 26 months (range, 12–84 months) after internal fixation. The following were studied: age, smoking history, energy of the trauma, fracture type and displacement, skin integrity and intra-operative appearance of the radial nerve.

Of the 17 palsies, 13 were present preoperatively, including 10 that recovered (PreR group) and 3 that did not recover (PreNR group). Plate fixation and radial nerve exploration were performed in all patients. Of the 10 PreR patients, 6 had nerve contusion and 2-nerve entrapment. Of the 3 PreNR patients, 2 had gross nerve damage and 1 nerve contusion and a history of spinal muscular atrophy. Only age and presence of gross nerve damage differed significantly between the PreR and PreNR groups; trends towards significant differences were noted for skin breach and fracture displacement. Of the 4 postoperative radial nerve palsies, 2 recovered fully and 2 partially; mean age was higher in the 2 patients with partial recovery.

These findings are consistent with the few previous studies of outcome predictors in radial nerve palsy. Factors such as major fracture displacement and high-grade skin wounds probably promote the occurrence of gross nerve lesions. The high incidence of nerve entrapment and stretching supports routine nerve exploration during internal fixation in patients with preoperative radial nerve palsy.

IV, retrospective study with no control group.