A risk prediction model for poor joint function recovery after ankle fracture surgery based on interpretable machine learning.

Objective: Currently, there is no individualized prediction model for joint function recovery after ankle fracture surgery. This study aims to develop a prediction model for poor recovery following ankle fracture surgery using various machine learning algorithms to facilitate early identification of high-risk patients. Methods: A total of 750 patients who underwent ankle fracture surgery at Lu'an Hospital Affiliated to Anhui Medical University between January 2018 and December 2023 were followed up. The collected data were chronologically divided into a training set (599 cases) and a test set (151 cases). Feature variables were selected using the Boruta algorithm, and five machine learning algorithms (logistic regression, random forest, extreme gradient boosting, support vector machine, and lasso-stacking) were employed to construct models. The performance of these models was compared on both the training and test sets to select the best-performing model. The decision basis of the optimal model was further analyzed using Shapley Additive Explanation (SHAP) and Local Interpretable Model-Agnostic Explanations (LIME). Results: In total, 12 characteristic variables were identified using the Boruta algorithm. Among the five machine learning models, random forest model: AUC (training set: 0.840, test set: 0.779), accuracy (training set: 0.781, test set: 0.742); SVM: AUC (training set: 0.809, test set: 0.768), accuracy (training set: 0.751, test set: 0.728); XGBoost: AUC (training set: 0.734, test set: 0.748), accuracy (training set: 0.668, test set: 0.722); logistic regression: AUC (training set: 0.672, test set: 0.691), accuracy (training set: 0.651, test set: 0.656); lasso-stacking model: AUC (training set: 0.877, test set: 0.791), accuracy (training set: 0.796, test set: 0.762). The PR curve and decision curve of the lasso-stacking model were better than those of other models. The lasso-stacking model had the best performance. SHAP analysis showed that functional exercise compliance, combined ligament injury, and open fracture accounted for the largest proportion of SHAP values and were the most important influencing factors. Conclusion: Through evaluation and comparison of the developed models, the lasso-stacking model demonstrated the best performance and is more suitable for predicting joint function recovery after ankle surgery. This model can be further validated externally and applied in clinical practice.