The Kinematic and Static Analysis of the Tibio-Femoral Joint Based on a Novel Spatial Mechanism

To reveal the characteristics of knee movement and tibio-femoral joint contact force, a novel single degree of freedom spatial mechanism is built to simulate the joint kinematics based on a three dimensional model of the human knee. The length changes of the three ligaments can be obtained by establishing and solving the kinematics spiral function. Based on this mechanism, a static model is built where linear springs are used to model the ligaments and whose stiffness coefficients are obtained by the finite element method. The main strength of the proposed model is that it associates the knee's flexion motion with internal/external rotation of the tibia based on the isometricity of the anterior cruciate ligament. This offers an efficient method to model and analyse the changes of ligament lengths and static kinematics after ligament reconstruction, which is crucial in designing knee recovery and rehabilitation equipment