Computer simulation of knee arthrometry to study the effects of partial ACL injury and tibiofemoral contact

We simulated the knee arthrometry test to obtain a deeper understanding of the joint´s stability behavior and interpret the arthrometric results more effectively. A 2D sagittal plane finite element model of the lower limb in the standard configuration of knee arthrometry was developed using ANSYS APDL. A detailed model of the knee joint was considered including the femoral articulating contour represented by an ellipse, the tibial plateau represented by a circular arc, and four major knee ligaments and their individual bundles represented by linear and nonlinear tensile springs. A deformable layer of articular cartilage was also considered over the tibial plateau to simulate the bones engagement more precisely. The model was analyzed while the tibia was subjected to an anterior drawer force of up to 150 N with 10 N increments and the tibial anterior translation was obtained. Simulation of the arthrometry test for different curvatures of the tibial plateau revealed that the bones engagement has a considerable effect on the knee joint´s laxity. However, a considerable change from the intact knee´s data curve was only observed when the ACL total ruptured was simulated. This emphasizes the difficult task involved when trying to distinguish the partial injuries of the ACL using arthrometric data.