Importance

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Abstract

A constrained prosthetic knee for surgical replacement of a dysfunctional knee includes a tibial platform, a movable bearing element, a hinge portion, and a femoral component. In one embodiment of the invention, the femoral component is typically constructed of a cobalt-chromium or titanium alloy and includes an upward extension for securing the femoral component to the femur. The femoral component, in this embodiment, includes a convex curve which rotatably and/or slidably engages the movable bearing, typically constructed of high molecular weight polyethylene. The superior surface of the bearing element is designed to congruently slidably engage the inferior surface of the curved portion of the femoral component. The inferior surface of the femoral component is generally convex with a radius of curvature matching the superior surface of the bearing element. The inferior surface of the femoral component may have more than one radii of curvature at different points along the convex surface. The superior surface of the tibial platform is generally flat and may include one or more protrusions for controlling the movement of the bearing element as it slides on the superior surface of the tibial platform. The hinge portion of the prosthetic device includes a lateral hinge pin and a yoke which rotatably mounts the femoral component on the tibial platform and provides two planes of rotation. The tibial platform includes a depending stem for securing the tibial portion to the tibia. A coaxial superior-inferior shaft within the tibial stem supports the yoke to define the plane of rotation of the hinge portion relative to the tibial platform.

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First Claim