Predictors of Non-union in Subtrochanteric Femur Fractures: A Multivariate Logistic Regression Analysis

Subtrochanteric femur fractures account for 10-34% of all hip fractures. They typically occur in two distinct patient groups: young adults who sustain high-energy trauma and elderly individuals with osteoporotic bone following low-energy trauma. The subtrochanteric region has unique anatomical and biomechanical features, including poor vascularity, high cortical density, and strong deforming muscle forces. These factors make stable fixation and timely union difficult to achieve. Intramedullary nailing is the most commonly used treatment method. However, complications, such as mal-reduction, non-union, and implant failure remain common. Identifying predictors of poor outcomes is crucial for guiding surgical planning and enhancing functional outcomes.

We analysed subtrochanteric fractures in skeletally mature patients treated surgically at our centre between January 2021 and December 2023. Patients with insufficient follow-up, pathological fractures, or prior surgery elsewhere were excluded. Radiographic and clinical records were reviewed to evaluate complications and outcomes. Statistical analysis included chi-square tests, ANOVA, and logistic regression.

A total of 85 patients were included (mean age: 45.3 ± 16.8 years; 83.5% male). Most fractures were caused by high-energy trauma, with 55% classified as Seinsheimer Type 3-5. Proximal femoral nailing (PFN) was used in 84.7% of cases. Radiological union was achieved in 75.3% of patients, with a mean healing time of 18.5 weeks. Non-union occurred in 16.5%, delayed union in 7%, and varus malalignment in 14.1%. Functional outcomes were good to excellent in 84.7% based on the Harris Hip Score. Multivariate analysis identified age ≥ 60 years (aOR 3.12), diabetes mellitus (aOR 2.67), Seinsheimer Type 3-5 fractures (aOR 2.89), and medial wall comminution (aOR 4.05) as independent predictors of poor outcomes.

Subtrochanteric fracture outcomes are strongly influenced by fracture complexity, patient comorbidities, and reduction quality. Medial wall integrity is a key determinant of union and implant success. Tailored surgical strategies and early risk identification are critical to improving prognosis.