Three dimensional modeling of the knee joint: prediction of ligament related gait abnormalities

Abstract

The purpose of this study is to investigate the affect of anterior bundle of ACL (aACL), anterior portion of posterior cruciate ligament PCL (aPCL), anterior and deep portions of MCL (aMCL, dMCL) and the tibiofemoral articular contacts on to passive knee motion. A well accepted reference model for a normal tibio-femoral joint was reconstructed from the literature in which attachments of the bundles of the ligaments and the articular surfaces in medial and the lateral components were carefully defined. Another three dimensional dynamic tibiofemoral model which includes the isometric fascicles, aACL, aPCL, aMCL, dMCL, and the medial-lateral articular surfaces were represented as the constraints to predict the trajectory of the tibia on the femur during flexion. The tibiofemoral model was also integrated in to the dynamic patella-tibio-femoral model. The behavior of the knee model was also tested by simulating dynamic and static clinical tests such as knee extension exercise and drawing test. The patello- tibio-femoral model was integrated into full-body model to simulate people walk with normal and ACL deficient patterns. The predictions were closely agreed with the literatures and correspond well to measurements of the model which represents natural patello-tibio-femoral joint. The aACL, aPCL, aMCL, dMCL bundles and the medial-lateral articular surfaces might play a primary role to give the nature of distal femoral sphere like shape. The clinical significance of the work is that anything which changes the lengths and locations of the related ligaments may demolish natural constraints and force the articular structures in to unnatural shape which may make the knee to change contact behavior on the articular surface and may cause pain. The surgical treatments must be accurate enough to provide both ligament bundle geometries and articular geometry to achieve a problem free knee kinematics after the surgery.|Keywords: Knee, Kinematics, Geometry, Three-dimensional model, Ligament surgery.