Risk factors for non-union in humeral shaft fractures: a retrospective analysis of intramedullary nailing outcomes

Abstract

Background: Intramedullary nailing is the primary surgical treatment for many humeral shaft fractures. Non-union in these patients require new surgical treatments, with severe impact on the quality of life; identifying the risk factors associated with non-union is crucial to reduce this evolution. The goal of this retrospective cohort study is to analyze the aspects that can lead to non-union in humeral shaft fractures treated with intra-medullary nailing.
Methods: The authors retrospectively analyzed cases of humeral aseptic non-union treated with nail removal and Open Reduction Internal Fixation (ORIF) with a locking compression plate, in a single hospital between November 2013 and June 2024. From 33 identified cases, 20 patients met our inclusion criteria: age over 18 years, humeral shaft fractures (AO/OTA 12-A1 or 12-B2) involving the deltoid tuberosity treated with antegrade intramedullary nailing and failure of healing after 12 months. All the non-unions were not infected and vital normo or hypertrophic. The following exclusion criteria were applied: age under 18 years, pathological fractures, fractures treated non-surgically, or fractures treated with devices other than antegrade intramedullary nails.
Results: 20 patients (mean age 49 ± 10.6 years; 13 males, 7 females) underwent revision surgery with plate fixation after failed intramedullary nailing. Left-sided fractures accounted for 45% of cases. AO/OTA 12-A2 was the most prevalent fracture pattern (55%), followed by 12-B2 (40%). Among the twenty patients, the fracture at the deltoid insertion was involved with a “V” fragment in thirteen cases of nonunion. The mean overall follow-up was 11 ± 3 months. Complete radiographical union was achieved in 19 patients (95%) with a mean time to bony union of 7.1 ± 3.5 months. No deep infections or osteomyelitis occurred. 
Conclusions: The results of this study contraindicate IM nailing in humerus fractures AO types 12-A1, 12-A2, and 12-B2 with displacement of the “V” fragment. The non-union occurs due to the difficulty in reducing and fixing the “dynamic” gap caused by deltoid traction and the slow healing of that area. The solution for the vital non-union is to reduce the gap and use plate fixation, and this treatment is recommended, especially in an acute setting.