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: In order to improve a modular implant part for replacing a part of a natural knee joint with an implant component comprising a shaft extending away from the implant component and a connecting device for connecting the shaft to the implant component such that the shaft is adapted to be fixed to the implant component in a multiplicity of desired positions in a simple manner, it is proposed that the connecting device be formed in such a manner that, in a mounting disposition, the shaft is adapted to be moved into different translatory positions by a translatory movement in a direction transverse or substantially transverse to its longitudinal axis, and that, in an implantation disposition, the shaft is adapted to be fixed immovably to the implant component in one of the different translatory positions. Furthermore, an improved knee joint prosthesis is proposed.

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 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: In order to improve a modular implant part for replacing a part of a natural knee joint with an implant component comprising a shaft extending away from the implant component and a connecting device for connecting the shaft to the implant component such that the shaft is adapted to be fixed to the implant component in a multiplicity of desired positions in a simple manner, it is proposed that the connecting device be formed in such a manner that, in a mounting disposition, the shaft is adapted to be moved into different translatory positions by a translatory movement in a direction transverse or substantially transverse to its longitudinal axis, and that, in an implantation disposition, the shaft is adapted to be fixed immovably to the implant component in one of the different translatory positions. Furthermore, an improved knee joint prosthesis is proposed.