An implant for coxofemoral prosthesis comprises a slightly conical approximately straight tail that is to be engaged in the medullary cavity of the femur and a body carrying the lug or neck of a ball-and-socket joint, the body being connected to the tail by an upper part or head formed by at least one inclined projection intended to be applied against the surface of the femur cut after its resection at the level of the large trochanter. The implant is characterized in that the projection predominates over the anterior and posterior faces of the tail, and is greatly inclined from the side of the internal cortical wall to constitute a sliding shoe, allowing automatic placing of the implant on the inside the medullary canal.

The anchoring shank is provided with a plurality of depressions which are arranged in fish-scale manner. Each depression is of arch-like shape with flanks which taper conically towards the proximal end of the shank. In addition, each depression merges into the shank at the distal end while having a trough parallel to the axis of the shank. The depressions serve to improve the adhesion between the bone cement bed and the shank obviates looseness caused by shrinkage of the bone cement bed.

The shank of the prosthesis is provided with a plurality of parallel grooves in order to improve adhesion of the shank in a prepred bone cavity. The grooves are used to improve adhesion either directly to bone tissue or to a cement bed within a bone cavity. The grooves are spaced apart on a center-line to center-line distance of a few millimeters and each has a depth of several tenths of a millimeter.

A hip-joint prosthesis which provides for universal motion about three transverse pivot axes comprising a femoral member adapted to be coupled to the femur and a cup assembly partially receiving the femoral member. The cup assembly is slidably received in the acetabulum. Motion about one of the pivot axes can occur in the prosthesis and motion about the other two pivot axes is forced to occur between the cup assembly and the acetabulum.

This invention describes a femoral twin-stem for a hip endoprosthesis. The ateral stem portion and the medial stem portion are connected by a bridge. The neck of the femoral twin-stem is connected to the proximal section of the lateral stem portion. The proximal prong of the medial stem portion and the distal prong of the lateral stem portion allow for a gradual load transfer to the bone since they can be individually designed with a proper geometry all the way to their respective tips. Gradual load transfer in turn reduces stresses in the bone cement mantle and improves the long term results of the hip replacement effected with this femoral twin-stem.