High performance knee prostheses

摘要

Knee prostheses featuring components that more faithfully replicate the structure and function of the human knee joint in order to provide, among other benefits: greater flexion of the knee in a more natural way by promoting or at least accommodating internal tibial rotation in a controlled way, replication of the natural screw home mechanism, and controlled articulation of the tibia and femur respective to each other in a more natural way. In a preferred embodiment, such prostheses include an insert component disposed between a femoral component and a tibial component, the insert component preferably featuring among other things a reversely contoured posterolateral bearing surface that helps impart internal rotation to the tibia as the knee flexes. Other surfaces can also be specially shaped to achieve similar results, preferably using iterative automated techniques that allow testing and iterative design taking into account a manageable set of major forces acting on the knee during normal functioning, together with information that is known about natural knee joint kinetics and kinematics.

主权项

1. A prosthetic knee implant, comprising:
a tibial insert having a medial bearing surface and a lateral bearing surface; and a femoral component having a medial condylar surface and a lateral condylar surface, the medial condylar surface being configured to contact the medial bearing surface and the lateral condylar surface being configured to contact the lateral bearing surface: (i) such that the femoral component and the tibial insert can move in flexion and extension with respect to one another; (ii) such that moving the femoral component and the tibial insert in flexion moves a contact point between the lateral bearing surface and the lateral condylar surface posteriorly along a track in an arcuate fashion from an anterior portion of the lateral bearing surface to a posterior portion of the lateral bearing surface; (iii) such that moving the femoral component and the tibial insert in flexion moves a contact point between the medial bearing surface and the medial condylar surface posteriorly from an anterior portion of the medial bearing surface to a posterior portion of the medial bearing surface; and (iv) such that moving the femoral component and the tibial insert in flexion permits an internal rotation of the tibial insert relative to the femoral component; wherein the lateral condylar surface is configured to move along a convex arc of the lateral bearing surface, the convex arc sloping in a distal-posterior direction; wherein the lateral bearing surface comprises a curved generally concave portion, and wherein the curved generally concave portion sweeps laterally from the anterior portion of the lateral bearing surface toward a middle portion of the lateral bearing surface and sweeps medially from the middle portion toward the posterior portion of the lateral bearing surface; and wherein the lateral bearing surface and the medial bearing surface have different contours.