Risk factors for nonunion after traumatic humeral shaft fractures in adults

INTRODUCTION: Humeral shaft fractures account for 3% of adult fractures. Optimal management remains a topic of debate given variable union rates reported in the literature after surgery or functional bracing. The primary aim was to compare these 2 cohorts of patients and their primary fracture union rates. A secondary aim was to identify predictors of nonunion. METHODS: A retrospective cohort study of 164 adult patients with traumatic humeral shaft fractures was performed. Fractures were classified according to the Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association classification. Primary outcomes included rate nonunion, including symptomatic fractures requiring conversion to open reduction and internal fixation (ORIF). Secondary outcomes included rates of complications and secondary procedures. RESULTS: Ninety-four (57%) patients were treated initially with ORIF. Nonoperative patients were older (47.1 vs. 41.5 years, P = .028) and had more medical comorbidity (62% vs. 43%, P = .017), low-energy trauma (62% vs. 34%, P < .0001), and isolated injuries (74% vs. 32%, P < .0001). All patients with open fractures (23%) were treated with débridement and ORIF, and surgical patients had more nerve injuries on presentation (36% vs. 9%, P < .0001). The overall rate of primary fracture union was 88%, similar after ORIF and nonoperative management (92% vs. 83%, P = .095). Multivariate analysis found alcohol abuse (odds ratio [OR]: 3.4, 95% confidence interval [CI]: 1.0-11.0, P = .046) and deep infection (OR: 19.9, 95% CI: 2.6-150.5, P = .004) to be significant predictors of nonunion. Chronic liver disease demonstrated a trend toward increased risk of nonunion (OR: 4.1, 95% CI: 0.8-20.9, P = .088). Seventeen operative patients (18%) developed 17 postoperative complications: iatrogenic nerve palsy (5%), deep infection (5%), and implant failure (3%), the most common. Reoperation rate was 10%, primarily for revision ORIF (4%). CONCLUSION: Patients managed nonoperatively were more often older patients with isolated fractures and more medical comorbidity. Surgical candidates were younger, more often with higher energy injuries, and were frequently with concomitant injury. Primary union occurred in 88%, with a trend toward a higher rate after ORIF. Patients with chronic liver disease and/or alcohol abuse are at greater risk for nonunion, irrespective of treatment.