Abstract: The hip joint socket is formed of a socket body of relatively elastic material, for example of plastic, and one or more reinforcement rings which are shrunk fit on the socket body under a prestress. The rings impart rigidity to the hip joint socket. The rings may protrude from the contour of the socket body or may have projections which protrude from the contour of the socket body in order to improve fixation in a cement bed or pelvic cavity.

Abstract: The injector is provided with an injection nozzle in the bottom of the cylinder tube for low pressure operation wherein large quantities of bone cement are to be injected. The injector also has a nozzle element which can be releaseably attached to the cylinder tube for high pressure injection. This nozzle element has a nozzle tube of reduced cross-sectional area through which a ram passes in the form of a piston in order to provide for high pressure injection.

Abstract: The hip joint socket is provided with a peripheral edge or flange in which a plurality of bores are formed. Each bore narrows conically from one side of the peripheral edge towards the free surface of the socket to provide outflow paths for excess bone cement which is displaced during implanting of the socket in a pelvis. The construction in the bores also permits the excess cement to harden into a rivet-like plug to increase the securement of the hip joint socket in the cement bed.

Abstract: 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.

Abstract: The prosthesis shank is composed of a blade which carries a joint head and a wedge-shaped end piece. The end piece is driven in along a guide in the lateral narrow side of the blade while the blade remains in a fixed position. The wedge-shaped form of the end piece permits fixation of the blade at a predetermined height such that the joint head can be at the level of the trochanter tip.

Abstract: The conical pin end of the male endoprosthesis part is provided with a deformable surface while the conically recessed articular ball is provided with inwardly directed lugs for penetrating into the deformable surface during mounting on the pin end. The lugs have a maximum height of 0.5 millimeters and a maximum width of three millimeters. The deformable pin surface may be formed by a screw thread, a plurality of circumferential grooves of wavy configuration or a plurality of circumferential ribs.

Abstract: The retention device is formed of a guide piece for slidably receiving the shank of an endoprosthesis and an anchoring element for anchoring the guide piece within a bone. The guide piece and anchoring element can be pushed together or threaded together. The anchoring element is provided with slits so as to facilitate expansion upon movement of the guide piece into the anchoring element.

Abstract: The socket body has an exterior surface which tapers in one direction while anchoring beads on the exterior surface taper in an opposite outward direction. The beads serve to anchor the body within a pelvis. In addition, cross ribs are formed on the anchoring beads with at least some of the ribs being elastic. Upon insertion of the socket, the ribs bend in a direction opposite to the direction of insertion. The two oppositely directed anchoring tapers of the socket body and the beads provide a firm fit of the socket body in a pelvis with a cement-free anchoring. Also, the bent ribs tend to resist withdrawal of the socket from the pelvis.

Abstract: 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.

Abstract: The anchoring surface of the bone implant is provided with villi (depressions or projections) devoid of corners and edges. The villi are of generally conical shape with transition surfaces merging into the base level of the anchoring surface. The villi allow implanting in a bone without cement since bone tissue is allowed to grow into or around the villi.

Abstract: The bone implant is made from elements which have different mechanical properties and which are maintained out of contact from each other by means of a plastic member. The plastic member is disposed in and fills a gap formed by the implant elements. In addition, the plastic member has thin-walled extensions which are engaged in narrowing sections at the outer boundaries of the gap. These extensions guard against any creep in the plastics member under the forces imposed on the plastics member during stressing of the bone implant.

Abstract: The joint implant utilizes a pin and socket arrangement wherein the pin and socket are of non-circular cross-sectional shapes. In addition, the socket has a shaped aperture which permits the pin to tilt or rock in the socket without twisting about the longitudinal axis of the pin. The socket has a reduced cross-sectional portion within which the pin is guided as well as widening portions within which the pin may tilt.

Abstract: The metal male joint part has a taper which is less than that of the cavity of the oxide ceramic female joint part. In addition, the surface of the male part has a resistance to deformation which is less than that of the core of the male part. The cone angle .beta. of the female cavity and the cone angle .alpha. of the male joint part are in the relation:tan .beta./2 - 0.001 .ltoreq. tan .alpha./2 .ltoreq. tan .beta./2 - 0.005.

Abstract: The joint head is mounted via a sleeve of a cup-shaped member to rotate and move axially relatively to a pin on the prosthesis stem while at least one groove-like recess is formed between the sleeve and joint head to allow passage of lubricant. The movement of the joint head produces a "reciprocating pump" effect on the lubricating fluid.

Abstract: The concave articular surface of the prosthetic acetabulum which receives a spherical joint head is formed with a groove which extends about the surface and joint head. This groove serves to distribute the lubricant within the joint during loading and unloading of the joint.

Abstract: An artificial head assembly for a human femur consists of the head portion roper and a metal pin. The head portion is a sintered ceramic ball having a polished contact face of convex, spherical curvature and a blind bore tapering conically inward toward the contact face. The pin is shaped for insertion of one end into the hollow stump of the femur, the other end tapering conically at the same apex angle as the bore in the ball. A knurling of the conical face of the pin reduces the compressive strength of the pin surface to less than the tensile strength of the ball so that the assembled head and pin can be sterilized without cracking the ceramic head portion because of differences in coefficients of thermal expansion between the metal and the ceramic material.

Abstract: An intermediate member is positioned between the proximal joint part and the distal joint part in order to permit increased hand movements. The intermediate member has a V-shaped recess which receives an extension of the proximal joint part and allows an extra degree of movement. The distal joint part has a spherical joint head which is snapped into a socket in the intermediate member.