Predictors of Traumatic Nerve Injury and Nerve Recovery following Humeral Shaft Fractures: Short title: Traumatic Nerve Palsy after Humeral Shaft Fracture.

Abstract

INTRODUCTION\nNerve palsy is common after humeral shaft fracture with the radial nerve being the most commonly injured nerve. Isolated nerve injuries usually recover spontaneously and operative intervention is rarely indicated. Our goal was to study the predictors of traumatic nerve injury and recovery in a large cohort of patients with humeral shaft fractures.\n\n\nMETHODS\nAfter obtaining IRB approval, 376 patients with humeral shaft fracture including 96 patients with documented traumatic nerve palsy and 280 with intact neurovascular exam on presentation were retrospectively included in the study. The primary outcome was incidence of a traumatic nerve palsy and the secondary outcome was nerve recovery.\n\n\nRESULTS\nNerve palsy was present in 96 (25.5%) patients at the time of injury. Radial nerve was the most commonly injured nerve (93.6%), followed by ulnar (5.1%), and axillary (1.2%) nerves. Seventeen patients (17.7%) had multiple nerves palsies. A multivariable regression analysis revealed that the concomitant vascular injury (OR: 52, 95% CI: 5.6-480.6), distal 1/3 fractures (OR: 6.3, 95% CI: 2.7-14.7) and middle 1/3 (OR: 2.8, 95% CI: 1.2-6.5) versus proximal fractures, open fracture (OR: 2.1, 95% CI: 1.1-4.4), and high-energy trauma (OR: 1.7, 95% CI: 1.1-2.9) were independent predictors of nerve palsy. Iatrogenic nerve injury was detected in 7 (4.6%) patients, all affecting the radial nerve. Spontaneous recovery of traumatic nerve injuries was detected in 87 (91%) patients with 19% partial and 72% complete recovery. Initial sign of recovery was observed at median times of 7 and 9 weeks for those managed conservatively or fracture fixation. Operative treatment of the fracture had no effect on the outcome of nerve recovery (88.5% vs. 100%; p=0.14). Ten (14.1%) patients had transected nerves at the time of exploration and open fractures (22.7% vs. 6.8%; p=0.04) and concomitant vascular injury (33.3% vs. 7.3%; p=0.02) were associated with nerve transection, portending a worse prognosis for nerve recovery compared to nerves in continuity (40% vs. 95.3%, p=0.004).\n\n\nDISCUSSION\nThe incidence of nerve injury after humeral shaft fracture was 25%, reflecting an abundance of high energy and open injuries in this cohort. Ninety one percent of patients experienced improvement in their nerve function with median time to recovery of 7-9 weeks. The operative treatment of the fracture did not change the rate of nerve recovery. Patients with multiple nerve palsies and concurrent vascular insult had worse nerve recovery. We recommend nerve studies if no sign of recovery is observed by 9 weeks.\n\n\nLEVEL OF EVIDENCE\nLevel III; Retrospective Case-Control Design; Prognosis Study.