Long-Term Evaluation of Ulnar Nerve Function in Patients With Distal Humerus Fractures Treated With Open Reduction and Internal Fixation: A Nerve Conduction Study

Abstract

Objectives: To investigate the long-term ulnar nerve function in patients with distal humerus fractures treated with open reduction and internal fixation using electromyography. Design: Retrospective cohort study. Setting: Level 1 trauma center. Patients: Fifty-two patients (20 men and 32 women) with distal humerus fractures between 2002 and 2017. Interventions: Open reduction and internal fixation with a minimum of 5 years of follow-up. Main Outcome Measurements: Nerve conduction tests for evaluation of ulnar nerve function. Secondary outcomes were modified McGowan grading system for symptoms of ulnar neuropathy. Results: The mean follow-up time was 112.7 ± 39 months after surgery. Fifteen patients (28.8%) scored in grade I, 30 (57.6%) in grade II, and 7 (13.6%) in grade III on the affected side according to McGowan grading scale. According to EMG results, 40.1% (21/52) of patients had abnormal results. There was significant differences between fracture and unaffected side regarding ulnar nerve motor wrist compound muscle action potential (CMAP) amplitude, motor below-elbow CMAP amplitude, above-elbow CMAP amplitude, above-elbow motor nerve conduction velocity, and sensory wrist amplitude. Ulnar nerve motor wrist-abductor digiti minimi latency (P = 0.01; r = 0.446) and ulnar nerve sensory conduction velocity (P < 0.001, r = −0.504) were significant correlation with McGowan grading scale. Conclusions: There were significant differences between fractured and unaffected side regarding ulnar nerve motor amplitude and sensory wrist amplitude. A mean decrease in sensory amplitude of fracture elbow was found to be 25% compared with the unaffected side in our result. Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.