Sulzer Orthopedics Inc.

Centerpulse Orthopedics Inc.

Vincent Leclercq

Bernhard Gyssler

Ren&eacute; Brack

Martin Aicher

A kit for a knee joint prosthesis includes a tibia part, a femur part and a meniscus part which is to be arranged between the femur part and the tibia part. The kit enables the assembly of different prosthesis types, namely of prostheses in which the meniscus part is arranged to be immobile relative to the tibia part and of prostheses in which the meniscus part is arranged so as to be movable relative to the tibia part. The kit includes a plurality of guiding elements which are formed in such a manner that the respective guiding element is in engagement with the tibia part and with the meniscus part when the prosthesis is assembled and determines the movability of the meniscus part relative to the tibia part.

Kit for a knee joint prosthesis

A tibia part for a knee joint prosthesis. The prosthesis includes a tibia bearing surface for the support of a bearing body and a bore for the reception of a guiding element. A cut-out for the rear cruciate ligament is provided in the tibia bearing surface and the bore is formed in such a manner that it can, depending on the design of the guiding element, receive the latter either rotationally fixedly relative to the tibia part or rotatably relative to the tibia part.

Tibia part for a knee joint prosthesis and a kit with a tibia part of this kind

A knee prosthesis has a medial condyle ( ) and a lateral condyle ( ), the running surfaces ( ) of which and the counter-surfaces A, B of which that lie on a tibia platform ( ) are sections of spherical surfaces with radii R , R , with their center M &prime; and M &prime; forming in their vertical projection onto the counter-surfaces A, B the points M , M . The lateral counter-surface B belongs to a lateral meniscus part ( ) which, guided on a plane ( ) of the tibia platform, is pivotal with the point M on a circular arc with radius R about the point M , with the radius R corresponding to the distance a of the centers M &prime;, M &prime;.

Knee implant

A mono-condylar knee joint prosthesis that includes a femur part having a convex running surface. The knee joint prosthesis further includes a tibia part having a sliding surface which faces the femur part and an intermediate part which is introduced between the femur part and the tibia part during implantation. The intermediate part has two bearing surfaces, namely a first, concave bearing surface for cooperating with the convex running surface of the femur part as well as a second bearing surface for cooperating with the sliding surface of the tibia part. A boundary surface is provided at the tibia part which bounds the sliding surface of the tibia part and projects pointing in the direction towards the femur part in order to be able to cooperate with a side surface of the intermediate part. The boundary surface which is provided at the tibia part is formed to be curved in the shape of an arch, and the intermediate part has a side surface which is curved corresponding to the boundary surface which is provided at the tibia part and which is curved in the shape of an arch.

Mono-condylar knee joint prosthesis

An artificial knee joint has a meniscus part ( ) which is displaceably journalled on a tibia platform ( ) and a guiding part ( ) which is rotatably journalled on the tibia platform ( ) and which engages into a guide ( ) of the meniscus part ( ), with the guiding part and the meniscus part having lateral guiding surfaces ( ) for guiding the meniscus part ( ). In order to limit the surface pressure between the guiding surfaces ( ) the lateral guiding surfaces ( ) have different radii of curvature (R , R ) which are greater than 10 cm, with the sum of the reciprocals of the radii of curvature /R /R being less than 0.2 cm .

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Winterthur, Switzerland

Vincent Leclercq