RESUMO
Introduction: Fractures of the humeral shaft account for about 3% to 5% of all fractures. Although conservative treatment remains the first choice, there are a number of surgical indications. Minimally invasive plate osteosynthesis shows good functional results. However, complications have been reported, such as non-union. Objective: To assess the prevalence and risk factors for non-union after treatment of humeral shaft fractures using minimally invasive plate osteosynthesis. Materials and methods: This retrospective study was carried out in patients treated by minimally invasive plate osteosynthesis between 2009 and 2019. Demographic data and variables related to the fracture that could influence bone healing were analysed. The unpaired t-test and Mann-Whitney test were used for the statistical analyses. Categorical variables were analysed using the chi-square test or Fisher's exact test. Results: The study population showed a male predominance (53 of 75, 70.7%). The average time for fracture healing was 19.8 ± 15.3 weeks. Seven patients developed non-union. Only the presence of an open fracture increased the likelihood of non-union. Conclusions: The prevalence of non-union in patients treated by minimally invasive plate osteosynthesis was 9.3%. Patients with open fractures were six times more likely to progress to non-union. Fracture characteristics (Arbeitsgemeinschaft für Osteosynthesefragen classification, fracture location and plate working length) did not influence progression to non-union.