Abstract: A knee prosthesis having a femoral component with two condyles, an opening disposed between the two condyles, and a tibial component having bearing surfaces to engage and support each of the femoral component condyles. Moving the femoral and tibial components in flexion from about 0° to about 165° causes medial pivot rotation of the femoral component upon the tibial component. Rotation may be caused by interaction between an asymmetrical cam extending between the femoral condyles and a post disposed between the bearing surfaces and extending superior from the tibial component. Rotation may alternatively be caused by asymmetrical medial and lateral condyles which translate posteriorly upon respective medial and lateral bearing surfaces at disparate rates, without a femoral cam, a tibial post, or a post/cam contact surface. Embodiments of the knee prosthesis may be used in cruciate-substituting or cruciate-retaining procedures. Embodiments of the knee prosthesis may also prevent roll forward.

Abstract: A knee joint endoprosthesis is provided which consists of a femur component and a tibia component having cooperating joint surfaces in contact with one another. A rotation guide arrangement is provided for forcing the femur component and the tibia component to rotate relative to each other about a medial center of rotation as a result of a flexure of the knee joint endoprosthesis. The rotation guide arrangement having a first guide element with a first guidance surface and a second guide element with a second guidance surface which cooperates with the first guidance surface. A projection of the tibia component comprises the first guide element and a transverse extension connecting condyles of the femur component comprises the second guide element. The first guidance surface defines a first radius of curvature and the second guidance surface defines a second radius of curvature. The first and second radii of curvature are identical.

Abstract: A knee joint endoprosthesis is provided with a simplified construction. The knee joint endoprosthesis consists of a femur component and a tibia component which comprise cooperating joint surfaces that are in contact with one another. A rotation guide arrangement is provided for forcing the femur component and the tibia component to rotate relative to each other about a medial center of rotation upon a flexure of the knee joint endoprosthesis. The rotation guide arrangement comprises a first guide element having a first guidance surface and a second guide element having a second guidance surface which cooperates with the first guidance surface. The tibia component comprises the first guide element and the femur component comprises the second guide element. The first guidance surface defines a first radius of curvature and the second guidance surface defines a second radius of curvature. The first and second radii of curvature are identical.

Abstract: A knee prosthesis includes a femoral component having two condyles and an asymmetrical cam extending between the condyles. The cam has a medial end and a lateral end. The knee prosthesis also includes a tibial component having bearing surfaces and a post disposed between the bearing surfaces. The femoral component and tibial component are engageable by contact between the femoral condyles and tibial bearing surfaces, and by contact between the cam and post. The cam includes a first curvature defined by a first plane passing through the cam, and a second curvature defined by a second plane passing through the cam, the first curvature having a first vertex, and the second curvature having a second vertex, the distance between the first vertex and a medial plane being greater than the distance between the second vertex and the medial plane.

Abstract: A knee prosthesis includes a femoral component having two condyles and an asymmetrical cam extending between the condyles. The cam has a medial end and a lateral end. The knee prosthesis also includes a tibial component having bearing surfaces and a post disposed between the bearing surfaces. The femoral component and tibial component are engageable by contact between the femoral condyles and tibial bearing surfaces, and by contact between the cam and post. The cam includes a first curvature defined by a first plane passing through the cam, and a second curvature defined by a second plane passing through the cam, the first curvature having a first vertex, and the second curvature having a second vertex, the distance between the first vertex and a medial plane being greater than the distance between the second vertex and the medial plane.

Abstract: A knee prosthesis having a femoral component with two condyles, an opening disposed between the two condyles, and a tibial component having bearing surfaces to engage and support each of the femoral component condyles. Moving the femoral and tibial components in flexion from about 0° to about 165° causes medial pivot rotation of the femoral component upon the tibial component. Rotation may be caused by interaction between an asymmetrical cam extending between the femoral condyles and a post disposed between the bearing surfaces and extending superior from the tibial component. Rotation may alternatively be caused by asymmetrical medial and lateral condyles which translate posteriorly upon respective medial and lateral bearing surfaces at disparate rates, without a femoral cam, a tibial post, or a post/cam contact surface. Embodiments of the knee prosthesis may be used in cruciate-substituting or cruciate-retaining procedures. Embodiments of the knee prosthesis may also prevent roll forward.

Abstract: A knee joint endoprosthesis is provided with a simplified construction. The knee joint endoprosthesis consists of a femur component and a tibia component which comprise cooperating joint surfaces that are in contact with one another. A rotation guide arrangement is provided for forcing the femur component and the tibia component to rotate relative to each other about a medial centre of rotation upon a flexure of the knee joint endoprosthesis. The rotation guide arrangement comprises a first guide element having a first guidance surface and a second guide element having a second guidance surface which cooperates with the first guidance surface. The tibia component comprises the first guide element and the femur component comprises the second guide element. The first guidance surface defines a first radius of curvature and the second guidance surface defines a second radius of curvature. The first and second radii of curvature are identical.

Abstract: A knee prosthesis having a femoral component with two condyles and an opening disposed between the two condyles. The prosthesis includes a cam extending between the condyles forming a posterior boundary to the opening. Also included is a tibial component having bearing surfaces to support each of the femoral component condyles, and a post disposed between the bearing surfaces and extending superior from the tibial component. The femoral component and tibial component are engageable by contact between the femoral condyles and tibial bearing surfaces, and by contact between the cam and post during at least a portion of flexion between the femoral and tibial components. Moving the femoral and tibial components in flexion from about 45° to about 145° causes a contact region between the cam and post to move inferiorly from a first contact region to a second contact region while also causing rotation between the tibial and femoral components.