Intra-operative subperiosteal elevation of the ulnar nerve is a safe and effective way to minimize post-operative ulnar neuritis in distal humerus fractures.

Objectives: To describe subperiosteal elevation of the ulnar nerve and compare to anterior transposition and in situ decompression techniques.

Methods: Design: Retrospective comparative study.

Setting: Urban Level 1 trauma center.

Patient selection criteria: Distal humerus fractures (OTA/AO 13) treated with open reduction internal fixation between 2014-2022.

Outcome measures and comparisons: Rate of pre- and post-operative neuritis grouped by management of the ulnar nerve. During subperiosteal elevation, the ulnar nerve was identified and raised off the ulna subperiosteally and mobilized submuscularly anterior to the medial epicondyle to protect the nerve. The nerve was released only laterally off the triceps and the medial soft tissue attachment is maintained. The main outcomes measurements was rate of neuritis documented within physical exam.

Results: Within the 125 patients, 35 underwent subperiosteal elevation (mean age of 56 ± 21 years, 57% female), 63 in situ decompression (mean age of 60 ± 18 years, 46% female), and 27 anterior transposition (mean age of 55 ± 20 years, 59% female). Pre-operative ulnar neuritis was present in 34%, 21%, and 33% of patients treated with subperiosteal elevation, in situ decompression, and anterior transposition, respectively (p=0.26). At post-operative evaluation symptom resolution occurred in 100%, 69%, and 33% of patients treated with subperiosteal elevation, in situ decompression, and anterior transposition, respectively (p=0.003). New cases of post-operative ulnar neuritis occurred in 6%, 8%, and 26% of patients treated with subperiosteal elevation, in situ decompression, and anterior transposition, respectively (p=0.054). Subperiosteal elevation outperformed anterior transposition regarding post-operative ulnar neuritis (p=0.019) and symptom resolution (p=0.002) and performed similarly to in situ decompression (p>0.05). On multiple regression analysis, anterior transposition was an independent risk factor for post-operative neuritis (OR=5.2, p=0.023).

Conclusions: Subperiosteal elevation is an effective way to minimize post-operative neuritis and similar to an in-situ decompression during distal humerus fracture fixation. Based on the results of this cohort, authors recommended that anterior transposition of the ulnar nerve be used with caution due to association with post-operative ulnar neuritis.

Level of evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.