A 3D model analysis of knee prosthetic motion (2nd report, variations of articulating pattern for prosthetic geometries and walking conditions)

The object of this study is to introduce contact points' trajectories on the articulating surfaces and kinematics of knee prosthesis under various walking conditions for various types of prosthesis to help to design new prosthesis. After creating a 3D mathematical model including the tibio-femoral and patello-femoral compartments of prosthesis, we performed simulation analyses using the model. In the simulation, we employed three typical types of prostheses; conformity, laxity and flat types, for normal and elderly gaits and an elderly gait with a misaligned prosthesis. The simulation results demonstrated that trajectories and pressure of contact points on the articulating surfaces were much influenced by the prosthetic types and their alignments. The results also demonstrated that in some cases elderly gait exhibits unbalance of joint contact forces between the medio and lateral sides, excessive posterior deviation of contact points on the tibial surface. This warns against the current notion that the prosthesis may be more endurable for elderly gait for its less activity than normal gait.