Foot Pronation after Prolonged Running Increased the Medial Contact Force in the Knee Joint:A Study Based on OpenSim Modelling and Machine Learning Prediction

Objective: To reveal the changes of loads in the lower extremity,foot postures and knee contact force and validate their correlations after long-distance running in runners,aiming to provide easily-measured parameters for rapid prediction of loads on knees. Methods: OpenSim subject-specific modelling was used to analyse lower extremity joint angles,moments and knee contact forces after 5-km running. One-dimensional statistical parametric mapping was used to test the statistics. Machine learning algorithm was developed,trained and tested by using foot posture index and total,medial and lateral knee contact forces. Results: 1)After 5-km running,the significantly increased angles of hip extension in push-off,hip external rotation in the early stance and ankle plantarflexion during stance were found;2)Significantly increased moments of hip extension during stance,abduction in early stance and ankle plantarflexion during stance were found;however,knee flexion moment was decreased significantly in early stance and push off;3)Total knee contact force was reduced in the push off and lateral knee contact force was reduced in early stance and push off,but medial contact force was significantly increased in early stance;4)The machine learning algorithm showed that the total and medial knee contact forces were increased,but lateral knee contact force was reduced during foot pronation. Conclusion: 1)After 5-km running,the lower extremity showed magnitude and redistribution in the loads,which exhibited increased hip extension and abduction moments,reduced knee flexion moment and increased ankle plantarflexion moment,all of these changes may be related to foot posture changes and relevant muscle strength;2)Medial knee contact force was increased significantly at post 5-km running and showed linear correlation with foot posture index scores;3)Rapid prediction of knee contact force could be made by using foot posture index,and runners could evaluate foot postures on-site and estimate the magnitude and distribution of knee loads after running,which could assist with drawing up the running plan and distance,and reduce knee injury risks in running.