The biomedical study of the subsequent injury induced by MCL rapture

The rupture of the medial collateral ligament (MCL) occurs frequently during high valgus impact or sporting activities and commonly results in subsequent injuries. Experimental and clinical studies have been widely performed, but were limited to obtaining stress distribution and conducting parametric studies. The purpose of this study was to develop a validated three-dimensional finite element model of knee joint, and to analyze the kinematics and stress distribution of MCL deficient knee in response to typical loading and boundary conditions. The model was developed from magnetic resonance images and validated by the experimental data in the literature. The validated model was applied to analyze the kinematics and stress distribution of the MCL deficient knee exposed to three different loading cases: a valgus moment of 10Nm, an internal rotation of 15Nm and a posterior-anterior load of 200N. Valgus loading was found to be an important factor to abnormal stress distribution in MCL deficient knee. Instead, posterior-anterior loads exhibited few influences on the biomechanical behavior in MCL deficient knee. Under the internal rotation load, remarkable increase of stress in ACL only occurred when the knee flexed. The stability decreased with increasing flexion angle under all loading conditions. This study could help to understand the various subsequent injuries led by MCL injuries, and to predict the potential risks from external loads that should be avoided in rehabilitation.