Investigating the effects of knee joint motion schemes on knee joint injury: A finite element analysis

This study uses a three dimensional model of the knee joint to determine which knee joint motion schemes lead to ACL injury, while exploring the possible types of concomitant injuries associated with each motion scheme. The physical elements of the knee joint including bones, articular cartilage, meniscus and ligaments were obtained by reconstructing magnetic resonance images. A failure locus representing the relationship between motion schemes and knee joint injury was created from finite element simulations considering knee flexion, femoral axial rotation and both valgus and varus motion. The relationships between knee joint orientation and various tissue failures were examined and susceptibility spectrums for knee injuries were obtained. The posterolateral bundle demonstrated higher rupture susceptibility than the anteromedial bundle. The average varus angular displacement for ACL failure was 46.6\% lower than the average valgus angular displacement. Femoral external rotation decreases overall ACL valgus/varus failure angle by 27.5\% compared to internal rotation. Articular cartilage injury was shown to occur prior to ACL failure in all valgus simulations. A simplified and computationally efficient version of the full 3D model showed close correlation to the complete model with respect to ligament failure and shows that if only ligament failure is of interest, a simple model can be used. The results of this study highlight several detrimental joint motions and can aid in improved clinical diagnoses and improved training programs for athletes.