Artificial intelligence-driven elucidation of the mechanistic links between proximal joint strength and tibial loading in Medial Tibial Stress Syndrome runners: implications for precision rehabilitation.

OBJECTIVES: This study leveraged machine learning algorithms to observationally elucidate how proximal joint muscle activation patterns-particularly those involving the trunk and hip-are associated with the modulation of tibial loading during running. These findings may provide preliminary theoretical insights into reducing tibial loading during running in individuals with Medial Tibial Stress Syndrome (MTSS) and preventing recurrence. DESIGN: Cross-sectional design. SETTING: Biomechanics lab with musculoskeletal modeling and machine learning. PARTICIPANTS: A total of 174 recreational runners diagnosed with MTSS underwent biomechanical assessment during running, during which tibial loading was quantified. OpenSim modeling was subsequently performed to estimate muscle force production of proximal joints throughout the gait cycle. INTERVENTIONS: N/A. MAIN OUTCOME MEASURES: Three machine learning models-Extreme Gradient Boosting (XGBoost), Random Forest (RF), and Support Vector Regression (SVR)-were developed and integrated with the SHapley Additive exPlanations (SHAP) framework to characterize the relationships between proximal muscle force and tibial loading. RESULTS: Among the three models, XGBoost demonstrated the highest predictive accuracy. The SHAP dependence plots further identified several model-derived inflection features, indicating that tibial loading increased markedly when ipsilateral external oblique muscle force exceeded 10.417 N/kg, gluteus minimus force decreased below 0.776 N/kg, or piriformis muscle force exceeded 1.952 N/kg. These values should be interpreted as exploratory, model-dependent reference points rather than definitive clinical thresholds. CONCLUSION: Excessive force generated by the ipsilateral external oblique and piriformis, coupled with insufficient gluteus minimus force, markedly elevates tibial loading during running in individuals with MTSS. Based on these observational findings, we speculate that restoring bilateral balance in external oblique force and strengthening the hip abductors and internal rotators may help reduce tibial loading and thereby mitigate the risk of MTSS. However, this hypothesis requires confirmation in future intervention studies.