Post-Surgical Ulnar Nerve Neuropathy in Distal Humerus Fractures: Comparison Between In Situ Decompression and Anterior Subcutaneous Transposition

Abstract

Postoperative ulnar neuropathy is a common complication in patients undergoing surgery for distal humerus fractures, particularly when open reduction and internal fixation (ORIF) is performed. Objectives: This study aims to compare the rates of ulnar nerve neuropathy following classic in situ decompression versus ulnar nerve subcutaneous anterior transposition. Methods: A retrospective study was conducted, including 51 patients treated for distal humerus fractures with precontoured locking plates in our institution between 2009 and 2023, according to specific inclusion and exclusion criteria. Age, sex, ulnar neuropathy, range of motion (ROM), complications, surgical approach, and Mayo Elbow Performance Score (MEPS) were evaluated. Ulnar nerve function was graded according to modified McGowan classification. Results: Ulnar neuropathy was observed in 17 (33.3%) patients, with a higher risk in those who underwent anterior ulnar nerve transposition compared to in situ decompression (58% vs. 26%, p = 0.042). In the modified McGowan classification, 14 patients had grade 1 and 3 had grade 2 neuropathy. The overall complication rate was 49%, and the functional outcomes according to the MEPS scale showed a mean score of 81.6 (SD 17.29). The mean flexion-extension was 100.56°, and 94% of patients retained complete pronosupination. Conclusions: Our results demonstrate that routine intraoperative ulnar nerve transposition should not be performed for these fractures.

Keywords: fractures; humerus; nerve transposition; ulnar nerve; ulnar neuropathy.