Abstract: A hip joint femoral prosthesis has a rod, the proximal end of which has a cross-section of oval shape and a surface area increasing towards the proximal end. At least one wall of the proximal end includes alveoli therein hollowed out so as to present a maximum depth on their side towards the proximal end. The alveoli are of a circular or semi-circular shape and intersect, thereby providing a surface which improves the stability and anchoring of the prosthesis into the femur.

Abstract: An acetabular prosthesis assembly for implantation into a prepared acetabulum has a generally hemispherically-shaped cup. The cup has a substantially hemispherically-shaped inner surface and a substantially hemispherically-shaped outer surface defining a wall therebetween. The wall has a plurality of generally circular apertures therein for receiving a bone screw. The wall surrounding each aperture has a bevelled surface extending toward the outer surface followed by a generally cylindrical surface extending from the bevelled surface to the outer surface of the cup. The generally cylindrical surface of each aperture is threaded with threads of predetermined diameter and pitch. A bone screw has a first screw thread having a pitch and diameter for engagement with the thread of the cylindrical surface on the cup and a second screw thread having a major diameter and a pitch greater than the predetermined diameter and pitch of the cylindrical surface.