A 2D Model Analysis of Artificial Knee Joint during Deep Squatting

The objective of this study is to analyze kinetics and kinematics of artificial knee joint at deep flexion, using a 2D geometric model. Our knee model was composed of the tibio-femoral and patello-femoral joints, including the patella tendon and the quadriceps muscles. Since the model was 2D, it neglected the rotation and the varus/valgus motion. In the model, such assumption was made that articulation surfaces were rigid and a point contact was made. Also it was assumed that the force and moment equilibrium conditions were always satisfied. The motion to be studied was decided as the motion from standing to deep squatting with heel-rising. From the simulation we found such results that the femur did not make a rollback and contact force at post-cam became pretty large in high and deep flexion, indicating the post-cam mechanism did not function well. Also patello-femoral contact forces reached larger than tibio-femoral contact forces. Our results demonstrated that how to design the post-cam and patello-femoral joint should be critical issues for developing a new prosthesis which can make deep flexion.