Sulzer Brothers Limited

Sulzer Medizinaltechnik

Robert M Streicher

Rudolf Koch

Hansjorg Gysin

An endoprosthesis of compact thermoplastics including composite materials is disclosed. The endoprosthesis includes a plurality of prefabricated fibers such as carbon or aramid. Thermoplastics such as polyacrylates, polyaryl ether ketones, polycarbonates, polyether sulphones, polyethylenes or polyproplyenes are used as a binding agent. The prefabricated fibers have an internal core with predominately longitudinally oriented fibers and an enclosing covering with mutually intersecting fibers. The prefabricated fibers are cut to a length which is preferably five times their minimum diameter. The fibers are oriented substantially parallel to the major axis of the endoprosthesis. During molding and even in shallow cross- sections relative to the major axis of the endoprosthesis, each prefabricated fiber is at least partially overlapped by an adjoining prefabricated fiber. It is preferred that the prefabricated fibers at their ends take various forms including tapering, bevelled, and may have scooped, spherical or dished areas. A compression mold is used. The compression mold defines a female cavity which contains the elongate male profile of the endoprosthesis. Preheated prefabricated fibers are placed into the compression mold of the endoprosthesis. The fibers are all generally parallel to the major axis of the mold. Relative to cross-sections taken across the major axis of the mold, the number and array of the fibers varies as the particular cross-section varies. Specifically, at large cross-sections many fibers are found; at small cross-sections, the fibers are reduced in number.

Method of making an endoprosthesis of compact thermoplastic composite

The knee joint prosthesis is formed of a tibia metal plate which can be attached to a tibia and a femur part which can be secured in a femur. An intermediate plastic part is provided on the tibia metal plate to receive the femur part in bearing relation. In order to reduce abrasion of the intermediate plastic part, support members of hard material are distributed in the bearing surface of the intermediate plastic part to receive the femur part thereon. The bearing surfaces of the support members are integrated in the bearing surface of the intermediate part and are provided with dual surfaces to receive different bearing surfaces of the femur part, each of which has a different radius of curvature.

Knee joint prosthesis

The implant is made of two members which are relatively movable relative to each other. One member is made of hard material while the second member is made of a soft material. In addition, a plurality of support members of hard material are embedded in the soft member and each has a sliding surface to receive the hard member thereon in bearing relation.

Growing community of inventors

Winterthur, Switzerland

Robert M Streicher