Time From Injury to Surgical Fixation of Diaphyseal Humerus Fractures Is Not Associated With an Increased Risk of Iatrogenic Radial Nerve Palsy.

OBJECTIVES: To determine whether time from injury to fixation of diaphyseal humeral fractures and nonunions is associated with the risk of iatrogenic radial nerve palsy.

DESIGN: Retrospective review.

SETTING: Two Level 1 trauma centers.

PATIENTS/PARTICIPANTS: Between 2001 and 2015, 325 patients who had documented intact radial nerve function preoperatively were treated with fixation of a humerus fracture or humerus nonunion.

INTERVENTION: Open reduction and internal fixation.

MAIN OUTCOME MEASUREMENTS: Development of an iatrogenic radial nerve injury. Those with an injury were followed to either resolution of the nerve palsy or definitive treatment.

RESULTS: The risk of iatrogenic radial nerve palsy was 7.7% (25/325). Time to surgery was not significantly associated with iatrogenic radial nerve palsy. In a multiple variable analysis, when comparing patients treated within 4 weeks to those treated 4-8 weeks (P = 0.41), 8-12 weeks (P = 0.94), and over 12 weeks (0.20), there were no significant associations. Independent risk factors for iatrogenic radial nerve palsy included distal location of fracture (P = 0.04, odds ratio 3.71) and previous fixation (P = 0.03, odds ratio 3.80). Of the 25 iatrogenic nerve injuries, 22 recovered fully with expectant management, 1 was lost to follow-up, and 2 required either nerve graft or tendon transfers.

CONCLUSIONS: Time from injury to surgery does not seem to be a risk factor for developing an iatrogenic radial nerve palsy when treating diaphyseal humerus fractures. Patients with distal fractures, and those with previous fracture implants, are at increased risk of iatrogenic radial nerve palsy.

LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.