Risk factors for poor functional recovery at 6 months after ankle fracture surgery: A retrospective cohort study and...

This study aimed to investigate risk factors for poor functional recovery at 6 months after open reduction and internal fixation for ankle fracture, develop a predictive nomogram, and perform internal validation to support early identification of high-risk patients and formulation of individualized postoperative rehabilitation strategies. A retrospective cohort study was conducted including 582 patients with ankle fracture treated between January 2022 and December 2024. The primary outcome was poor functional recovery, defined as an AOFAS ankle-hindfoot score < 80 at 6 months postoperatively. Univariate and multivariate logistic regression analyses were performed to identify independent risk factors and construct a nomogram prediction model. Model discrimination was assessed using receiver operating characteristic curves and area under the curve (AUC). Calibration was evaluated using the Hosmer-Lemeshow test. Two internal validation approaches were applied: bootstrapping with 1000 iterations and 10-fold cross-validation; no independent external validation was performed. The events-per-variable ratio was 21.6 (108 events, 5 predictors), ensuring low overfitting risk. Sensitivity and specificity were calculated at the optimal threshold determined by the Youden index. Calibration curves and decision curve analysis were used to evaluate clinical utility. Overall, 153 (26.29%) patients exhibited poor functional recovery. Independent risk factors included age ≥ 65 years, postoperative VAS score ≥ 5, weight-bearing duration ≥ 4 weeks, posterior malleolus involvement, and ankle range of motion < 20°. The nomogram showed good discrimination with AUC of 0.842 in the modeling cohort and 0.802 in the validation cohort. After internal validation, the AUC was 0.822, with a sensitivity of 82.6% and specificity of 83.4%. The model was well-calibrated and achieved favorable net benefit in decision curve analysis. This internally validated nomogram based on a retrospective cohort demonstrates reliable efficacy in predicting poor 6-month functional recovery after ankle fracture surgery. It provides quantitative evidence for early risk stratification, precise intervention, and individualized postoperative rehabilitation management to improve functional outcomes.