The purpose of this study was to analyze associated factors of primary radial nerve palsy and to evaluate clinical outcome for its treatment in patients with humerus shaft fracture.

We divided two groups of patients with (17 patients) and without (116 patients) primary radial nerve palsy and analyzed correlation between radial nerve injury and various parameters, including age, sex, cause of injury, AO classification, fracture type, fracture location, and presence of open fracture. We also evaluated configuration of nerve injury, presence of recovery, and recovery time.

The overall prevalence of primary radial nerve palsy after humerus shaft fracture was 12.8% (17 palsies in 133 fractures). Younger age, AO type B, and distal 1/3 fractures showed significantly higher correlation with radial nerve palsy. No significant correlation was observed between radial nerve palsy and other parameters, including sex, cause of injury, fracture type, and presence of open fracture. Thirteen patients (76.5%) underwent early nerve exploration with internal fixation. Intraoperatively, all patients had continuity of radial nerve except one patient with segmental loss. At the final follow-up, 16 patients (94.1%) with radial nerve palsy had made a complete recovery. The mean time to complete recovery was 6.7 months.

Primary radial nerve palsy after humerus shaft fracture was more common in young age, AO type B, distal 1/3 fractures. Early surgical exploration can be recommended to confirm the condition of the radial nerve if the fracture should be fixed.