Risk Factors for Failure of Internal Fixation in Postmenopausal Patients With Osteoporotic Intertrochanteric Fractures

AIM: To identify independent risk factors for internal fixation failure after intramedullary nail fixation in postmenopausal patients with osteoporotic intertrochanteric fractures, and to develop and internally validate a predictive model for risk assessment. METHODS: The clinical data of 360 postmenopausal patients with osteoporotic intertrochanteric fractures admitted to The Second Affiliated Hospital of Liaoning University of Traditional Chinese Medicine from January 2021 to May 2024 were retrospectively analyzed. The patients were divided into the failure group (n = 65) and the success group (n = 295) according to whether internal fixation failure occurred within 6 months after the operation. General data, bone metabolism indices, imaging parameters, and surgery-related factors were collected. Univariate and multivariate logistic regression analyses were used to screen the independent risk factors of internal fixation failure. The receiver operating characteristic (ROC) curve was used to evaluate the model’s discriminative ability, while the Hosmer–Lemeshow test and bootstrap resampling calibration curve were used to evaluate calibration. Decision curve analysis was used to assess the clinical utility of the model. RESULTS: The failure rate of internal fixation was 18.06% (65/360). Multivariate logistic regression analysis showed that the quality of fracture reduction was poor (odds ratio (OR) = 3.07, 95% CI: 1.60–5.87, p < 0.01). The intramedullary nail position deviated from the center of the medullary cavity (OR = 2.38, 95% CI: 1.13–5.01, p = 0.02) was identified as an independent risk factor for internal fixation failure, whereas bone mineral density (BMD) T-score (OR = 0.17, 95% CI: 0.06–0.47, p < 0.01), femoral cortical thickness index (OR = 0.54, 95% CI: 0.38–0.79, p < 0.01), and lateral wall thickness (OR = 0.83, 95% CI: 0.76–0.90, p < 0.01) were independent protective factors. The model demonstrated good performance, with an area under the curve (AUC) of 0.83 (95% CI: 0.77–0.89). The Hosmer–Lemeshow test showed no significant difference between the predicted probability of the model and the actual observation (p = 0.28), and the calibration curve closely aligned with the ideal line. Decision curve analysis showed that the model had significant net clinical benefit within a wide threshold probability range. CONCLUSIONS: Poor quality of fracture reduction, the position of the intramedullary nail deviated from the center of the medullary cavity, lower bone mineral density, lower femoral cortical thickness index, and smaller lateral wall thickness are independent risk factors for the failure of internal fixation after intramedullary nail fixation in postmenopausal women with osteoporotic intertrochanteric fractures. The predictive model based on these factors demonstrates good discrimination, calibration, and clinical utility. Clinicians should pay close attention to the identified risk factors, thoroughly evaluate preoperative bone quality, achieve anatomical reduction, and ensure optimal positioning of the main nail during operation to reduce the risk of internal fixation failure and improve patient outcomes.