Impact of obesity on reduction quality and operative outcomes of proximal femoral nail for intertrochanteric femoral fractures in the lateral decubitus position

Abstract Background The aim of this study is to compare the clinical and radiological outcomes of proximal femoral nailing performed in the lateral decubitus position between obese and non-obese patients. Methods This retrospective cohort study, approved by the institutional ethics committee, included patients with acute AO/OTA classification types 31A1, 31A2, and 31A3 intertrochanteric femoral fractures treated with closed reduction and osteosynthesis using a short proximal femoral nail between 2022 and 2024. Obesity was defined as a body mass index of ≥ 30 kg/m 2 . Patients were divided into obese and non-obese groups, and clinical, radiological, and complication outcomes were compared between the two groups. Results A total of 533 patients were included, comprising 95 obese and 438 non-obese individuals. Obese patients were significantly younger and had higher Charlson Comorbidity Index scores ( p < 0.001). Operative time and intensive care unit admission rates were significantly higher in the obese group ( p < 0.001), and anesthesia type distribution differed between groups ( p < 0.001). Length of hospital stay and Harris Hip Scores were comparable ( p > 0.05). Radiologically, the distribution of tip–apex distance according to the 25-mm threshold did not differ between groups ( p = 0.244). However, optimal screw placement according to the Cleveland index was significantly less frequent in obese patients ( p < 0.001), and malposition in the lateral view was more common ( p < 0.001). Varus alignment and differences in reduction quality were also significantly associated with obesity status ( p < 0.001). Multivariable logistic regression analysis demonstrated that obesity remained an independent predictor of postoperative varus malalignment (OR 2.80, 95% CI 1.58–4.96; p < 0.001). Conclusion Obesity negatively affects reduction quality and operative parameters during proximal femoral nailing for intertrochanteric femoral fractures performed in the lateral decubitus position, although acceptable reductions can generally still be achieved. Furthermore, obesity remained an independent predictor of postoperative varus malalignment after adjustment for potential confounding factors. Surgeons should be aware of these technical challenges when treating obese patients and consider them during preoperative planning and intraoperative reduction maneuvers.