Three-dimensional knee model: constrained by isometric ligament bundles and experimentally obtained tibio-femoral contacts.

The purpose of this study is to investigate the effect of anterior portion of anterior cruciate ligament, posterior cruciate ligament, anterior and deep portions of medial collateral ligament and the tibio-femoral articular contacts on passive knee motion. A well-accepted reference model for a normal tibio-femoral joint is reconstructed from the literature. The proposed three-dimensional dynamic tibio-femoral model includes the isometric fascicles, ligament bundles and irregularly shaped medial-lateral contact surfaces. With the approach we aim to analyze bone shape and ligament related abnormalities of knee kinematics. The rotations, translations and the contact forces during passive knee flexion were compared against a reference model and the results were found in close accordance. This study demonstrated that isometric ligament bundles play an important role in understanding the femur shape from contact points on tibia. Femoral condyles are not necessarily spherical. The surgical treatments should consider both ligament bundle lengths and contact surface geometries to achieve a problem free knee kinematics after a knee surgery.

Interaction of ligament bundles and articular contacts for the simulation of passive knee flexion.

The purpose of this study is to investigate the effects of anterior bundle of ACL (aACL), anterior portion of PCL (aPCL), anterior and deep portions of MCL (aMCL, dMCL) and the tibio-femoral articular contacts on to passive knee motion. A three-dimensional simplistic anatomical dynamic model, based on the literature was used as a reference. This reference model attaches the bundles of the ligaments on medial and the lateral spherical condyles of the femur and tibial plateau giving us a representation close enough to a normal natural tibio-femoral joint, but does not allow to study abnormalities of the knee kinematics due to the assumptions of the femur shape. The proposed three-dimensional dynamic tibio-femoral model, however includes the isometric fascicles, aACL, aPCL, aMCL, dMCL, and irregularly shaped medial-lateral contact surfaces. The approach taken in this model is capable of ligament and bone surface modifications that will enable us to analyze bone shape and ligament related abnormalities of knee kinematics.