Routine Transposition or In Situ Decompression? Rethinking Ulnar Nerve Strategy in Distal Humerus Fractures.

Background: Fractures of the distal humerus (DHFs) represent challenging intra-articular injuries that are often followed by postoperative complications, most notably ulnar neuropathy. There is still debate regarding the best method of handling the ulnar nerve during open reduction and internal fixation (ORIF). Objective: The primary objective was to evaluate the incidence of postoperative ulnar neuropathy (UN) in patients who underwent open reduction and internal fixation (ORIF) for DHFs, comparing anterior transposition (AT) with in situ decompression (ISD) of the ulnar nerve. Additionally, we investigated the influence of AT on individuals presenting with preoperative UN. Methods: A retrospective review was conducted on 68 patients (26 females and 42 males; mean age: 46.3 years) who underwent ORIF for intra-articular DHF between 2018 and 2022. Patients were divided into two groups: anterior transposition (n = 14) and in situ decompression (n = 54). Ulnar neuropathy was evaluated using the modified McGowan classification, and radiographic outcomes were assessed with AO/OTA fracture classification. Results: Sixty-eight patients (26F/42M) were included. The mean age was 46.3 years (20-77 years) and the mean follow-up time was 53 months (36-76 months). The postoperative UN incidence was 30.8% (21/68). Neuropathy was significantly higher in the transposition group compared to in situ decompression (57.1% vs. 24%; p = 0.012). Olecranon osteotomy (36.3% vs. 20%; p = 0.042) and parallel plate configuration (33.3% vs. 12.5%; p = 0.037) were also associated with increased neuropathy risk. Among patients with preoperative ulnar neuropathy (n = 12), functional recovery was more favorable with transposition, where 71% experienced full resolution compared to 60% in the in situ group. Conclusions: Routine anterior transposition of the ulnar nerve during ORIF for DHF is associated with an increased risk of postoperative neuropathy and should be avoided in patients without preoperative symptoms. However, transposition appears beneficial in patients with pre-existing ulnar neuropathy. Surgeons should individualize ulnar nerve management to balance surgical risks and neurological outcomes.