MEDIAL ELBOW APPROACHES FOR CORONOID FRACTURES: RISK TO THE ULNAR NERVE

Coronoid fractures often require open reduction internal fixation (ORIF) to restore elbow stability. The flexor carpi ulnaris (FCU) split and flexor pronator split approaches are frequently used medial approaches to access the coronoid. The ulnar nerve can be released or transposed when performing these exposures. The optimal surgical approach and management of the ulnar nerve has not been clearly defined. Our purpose was to investigate and compare postoperative nerve complications in coronoid fractures undergoing ORIF following a FCU or flexor pronator split approach and ulnar nerve release or transposition. A retrospective review of 91 patients with coronoid fractures treated with ORIF using a medial approach from 2004 to 2022 was performed at three academic medical centres. Patients ≥ 18 years of age who sustained coronoid fractures with or without associated injuries were included. Patient charts and perioperative imaging were reviewed. Patient demographics, fracture classification, associated injuries, surgical approaches, ulnar nerve management, and postoperative complications were recorded. Primary outcomes assessed were signs and symptoms of postoperative ulnar nerve neuropathy. The mean age in the cohort was 45 ±16, 71% were males with a mean length of follow up of 16±22 months. Of the 91 coronoid fractures, 69 were O'Driscoll anteromedial fractures, eight were tips, and 14 were basal types. The incidence of preoperative ulnar neuropathy was 5% (n=5). The incidence of postoperative ulnar nerve neuropathy was not significantly different between in situ release 30% (n=9) or transposition of the ulnar nerve 34% (n=20), (p=0.64). Only 55% of the patients with a postoperative neuropathy completely resolved by final follow up. There was a significantly higher rate of postoperative resolution with transposition (70%) versus in situ release (22%), (p=0.045). The rate of postoperative ulnar neuropathy was not significantly different between the FCU or flexor pronator split approaches, (p=0.79). However, a significantly higher rate of neuropathy resolution occurred following the FCU split approach (p=0.026). While the incidence of postoperative ulnar nerve dysfunction is high with management of these fractures, using a FCU split approach and transposing the ulnar nerve led to a higher rate of neuropathy resolution. Larger cohorts and randomized clinical trials are needed to confirm these findings.