Protek Ag

Sulzer Medizinaltechnik Ag

Sulzer Brothers Limited

Walter Moser

Roland Willi

Ueli Wehrli

Markus Schneider

With the invention there is shown a C-shaped clip as a compression member (8) which can be inserted into a pocket (15) of a joint support (4) and which can itself be secured in this pocket against falling out of place by a latched arrangement. In this arrangement the two limbs of the clip act transversely to their spring direction as a spacer between a spring tongue (5) and a shoulder which are formed on the joint support (4). In this way a simple securing device arises which is recessed in the joint support (4) and which prevents springing back of the latched spring tongue (5) and is only loaded in compression. In the installed state the spring tongue (5) is not itself subjected to any alternating bending loads.

Tibia platform for a knee joint prosthesis

A screw-nut for screwing implants together includes a thrust-shoulder which projects radially and presses axially against part of a housing. The screw-nut further includes an internal threaded portion adapted to fit a corresponding screw part, and a plurality of members, each mounted onto the side of the thrust-shoulder facing away from the part of the housing against which the thrust shoulder presses. These members are adapted to receive a tool for tightening the screw-nut. A plurality of leaf springs is included for engaging the housing part. The leaf springs, the ends of which form latching-in dogs, project, in the axial direction, from the screw-nut. The leaf springs are constructed such that, when the thrust-shoulder makes contact with the housing part, each latching-in dog snaps into a recess in the housing part in order to prevent loosening of the screw-nut from the housing part.

Screw-nut for screwing implants together

With the invention is shown an artificial knee joint, in which the rear cruciate ligament and the collateral ligaments are assumed as being retained. A metal platform is attached to the tibia and perpendicular to the tibia axis has a plane surface, on which three slide members are slidably disposed so as to guide the metal platform relative to the femur condyles made of metal within the limits of the degree of freedom remaining to them under the tension of the ligaments. A central slide member forms an eminentia rotatable around a pin, which guides the femur condyles directly or indirectly with respect to rotation around the tibia axis and which along its median line, which extends in the sagittal direction in the non-rotated central position, forms a direct or indirect longitudinal guiding device for the femur condyles, while the flexion movement is guided at doubly curved femur condyles by the two outer slide members.

Meniscus platform for an artificial knee joint

An artificial knee joint has a convex femoral part (1) and tibial part (2). At the femoral part (1), which has smaller radii of curvature as bending increases, the tibial part (2) performs a rolling and sliding movement, with the femoral part (1) and the tibial part (2) each comprising a lateral guide surface (F.sub.2, F.sub.2 ') and a medial guide surface (F.sub.1, F.sub.1 '). The medial guide surface (F.sub.1 ') of the tibial part (2) forms a flat guide plane, which with different flex angles, abuts cylindrical guide surfaces (F.sub.1) of the femoral part (1) with line contact, while the lateral guide surface (F.sub.2 ') of the tibial part is trapped by the lateral condyle with different bending angles in the frontal plane in the lateral direction by line contact along circular segments having the same radius of curvature (R.sub.3). The value of this same radius of curvature (R.sub.3) lies between the smallest and largest flex radius (R.sub.n) of the lateral condyle in the track (7).

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Herrenschwanden, Switzerland

Walter Moser