Abstract: A femoral component of a knee prosthesis includes a bearing surface defined by a smooth, continuous surface which in one embodiment is entirely formed by a series of three segments of surfaces of revolution, the respective shapes of which are generated by rotating a common generating curve around three separate generating axes at respective pairs of major generating radii and through respective angles of rotation. The central segment of the surfaces of revolution constantly maintains the substantially same contact configuration with the superior bearing surface of a bearing insert over a range extending from full extension (0.degree. of flexion) to at least 45.degree. of flexion and up to 105.degree. of flexion. The maintenance of the substantially same contact configuration ensures area, point or line contact between the articulating surfaces which reduces contact stress and wear in flexion.

Abstract: A temporomandibular joint prosthesis is provided. The prosthesis includes the condyle component for attachment to the ramus of a temporomandibular joint to replace the natural condylar head. The condyle component is attached to the natural ramus by a fixation system that may include plasma-sprayed pegs or plasma-sprayed double screws. The prosthesis further includes a fossa component assembly having a metallic bone attachment member and a plastic bearing. The plastic bearing is disposed and configured for articular bearing engagement with the condyle component of the prosthesis.

Abstract: Joint endoprostheses, disclosed in the context of a total knee prosthesis, incorporate a first element for rigid connection to a first bone, the first element having an articulating surface; a second element for rigid connection to a second bone, the second element having a bearing surface which engages the articulating surface; wherein the engagement of the articulation surface with the bearing surface at any degree of relative rotation therebetween is reflected by a substantially constant contact configuration, the relative rotation of the device being accompanied by displacement of the bones toward and away from each other.

Abstract: Joint endoprostheses, disclosed in the context of a total knee prosthesis, incorporate a first element for rigid connection to a first bone, the first element having an articulating surface; a second element for rigid connection to a second bone, the second element having a bearing surface which engages the articulating surface; wherein the engagement of the articulation surface with the bearing surface at any degree of relative rotation therebetween is reflected by a substantially constant contact configuration, the relative rotation of the device being accompanied by displacement of the bones toward and away from each other.

Abstract: A tibia fixturing device comprises a metal tray formed with annularly spaced recesses in its underside at a depth of at least about 1.5 mm and from which a stem depends for axial insertion into a tibia conical cavity. The stem has a circular cylindrical portion proximal the tray and a conical portion distal the tray. Fins radially extend from the stem cylindrical portion and penetrate the tibia to provide some torsional resistance. Axially extending channels are formed about the stem periphery which channels have bottom surfaces parallel to the stem axis to provide further torsional resistance. The channels are arranged to not interlock with the cement in the axial direction to permit the cement to separate first from the device during axial removal of the device from the bone. The fins have inclined edges distal the tray and inclined radial outer edges to align and center the stem to the bone cavity edge.

Abstract: A prosthesis is provided having at least a smooth non-articulating load bearing surface disposed adjacent a bone. The prosthesis includes a substrate formed from a metallic alloy. At least the regions of the substrate defining the load bearing surface are coated with a biologically inert abrasion resistant material harder than the substrate for preventing leaching of ions from the substrate into adjacent body tissue and for preventing wear. The coating may be titanium nitride or zirconium or other such material exhibiting biological inertness and acceptable hardness. The coating preferably defines a thickness of 8-10 microns.

Abstract: A prosthesis is provided having at least a smooth non-articulating load bearing surface disposed adjacent a bone. The prosthesis includes a substrate formed from a metallic alloy. At least the regions of the substrate defining the load bearing surface are coated with a biologically inert abrasion resistant material harder than the substrate for preventing leaching of ions from the substrate into adjacent body tissue and for preventing wear. The coating may be titanium nitride or zirconium or other such material exhibiting biological inertness and acceptable hardness. The coating preferably defines a thickness of 8-10 microns.

Abstract: A femoral component with a femoral stabilizing implanted rod has condylar surfaces of different radii which mate with a thermoplastic bearing. A mating tibial platform is stabilized in the tibia with a rod, the bearing translating on the platform in the posterior-anterior directions in response to knee flexion and extension. The bearing bears the full extension load on congruent articulating contact regions with the condylar surfaces and lesser flexion loads via incongruent articulating contact. A hinge assembly is pinned to the femoral condylar component through a head having a depending shaft fixed to a thermoplastic tapered bearing axially floating and rotatably movable in a tibia platform component mating cavity. The head passes through the bearing and stops the bearing translations at extreme posterior and anterior positions.

Abstract: A prosthesis tibial bearing of thermoplastic material has a planar surface which engages the mating planar surface of a second prosthesis component such as the tibial platform. The typically metal platform edge wipes across the inner surface region of the bearing causing deformation of the bearing surface. This deformation causes stress magnification in the bearing at the platform edge region. The edge region of the platform planar surface is tapered to provide a gradual curved ramp between a relatively small corner radius at the platform edge and the platform planar surface, the tapered region being tangential to the edge radius and to the platform planar surface. The stress concentration increase at the edge region of the bearing is reduced at the platform edge region to below 100% and preferably to about 25% of the stress value between the bearing and the platform in the region interior the platform edge.

Abstract: A system of templates is provided for use during implantation of a prosthetic joint. The templates are of different surface areas and different thicknesses. The templates are first used to enable selection of a prosthetic component corresponding to the shape of a resected bone into which the prosthetic component will be implanted. The templates are then used to establish an appropriate prosthetic gap for the selected prosthetic component. The prosthetic gap will vary in accordance with the selected prosthetic component.

Abstract: A tibia fixturing device comprises a metal tray formed with annularly spaced recesses in its underside at a depth of at least about 1.5 mm and from which a stem depends for axial insertion into a tibia conical cavity. The stem has a circular cylindrical portion proximal the tray and a conical portion distal the tray. Fins radially extend from the stem cylindrical portion and penetrate the tibia to provide some torsional resistance. Axially extending channels are formed about the stem periphery which channels have bottom surfaces parallel to the stem axis to provide further torsional resistance. The channels are arranged to not interlock with the cement in the axial direction to permit the cement to separate first from the device during axial removal of the device from the bone. The fins have inclined edges distal the tray and inclined radial outer edges to align and center the stem to the bone cavity edge.

Abstract: A prosthesis is provided having at least a smooth non-articulating load bearing surface disposed adjacent a bone. The prosthesis includes a substrate formed from a metallic alloy. At least the regions of the substrate defining the load bearing surface are coated with a biologically inert abrasion resistant material harder than the substrate for preventing leaching of ions from the substrate into adjacent body tissue and for preventing wear. The coating may be titanium nitride or zirconium or other such material exhibiting biological inertness and acceptable hardness. The coating preferably defines a thickness of 8-10 microns.

Abstract: A joint prosthesis having a femoral element, a tibial element and a bearing for articulation therebetween is disclosed to further include an intermediate element. The intermediate element permits rotation of the bearing with respect to the tibial element and longitudinal translation of the bearing with respect to the intermediate element. Transverse translation of the bearing with respect to the intermediate element is precluded. In an alternative embodiment, the longitudinal translation may be limited either in the anterior or posterior direction.

Abstract: A prothesis tibial bearing of thermoplastic material has a planar surface which engages the mating planar surface of a second prothesis component such as the tibial platform. The typically metal platform edge wipes across the inner surface region of the bearing causing deformation of the bearing surface. This deformation causes stress magnification in the bearing at the platform edge region. The edge region of the platform planar surface is tapered to provide a gradual curved ramp between a relatively small corner radius at the platform edge and the platform planar surface, the tapered region being tangential to the edge radius and to the platform planar surface. The stress concentration increase at the edge region of the bearing is reduced at the platform edge region to below 100% and preferably to about 25% of the stress value between the bearing and the platform in the region interior the platform edge.

Abstract: A prosthetic component is provided for a condylar joint. The prosthetic component includes a platform having a bearing surface and a pair of side walls. The side walls include a pair of concave surfaces which face one another and define arcs of the same right circular cylinder. The prosthetic component also includes a plastic bearing having a bearing surface slidably engaged with the bearing surface of the platform. The bearing also includes thrust surfaces defining arcs of two right circular cylinders having radii less than the radius of the side wall surfaces of the platform. The thrust surfaces are spaced from one another to permit only limited sliding movement of the bearing in medial to lateral directions, but greater sliding movement in anterior to posterior directions.

Abstract: Joint endoprostheses, disclosed in the context of a total knee prosthesis, incorporate a first element for rigid connection to a first bone, the first element having an articulating surface; a second element for rigid connection to a second bone, the second element having a bearing surface which engages the articulating surface; wherein the engagement of the articulation surface with the bearing surface at any degree of relative rotation therebetween is reflected by a substantially constant contact configuration, the relative rotation of the device being accompanied by displacement of the bones toward and away from each other.

Abstract: An acetabular reamer is provided with a shaft having opposed front and rear ends. A mounting cap is securely connected to the front end of the shaft and includes a skirt having an interior surface spaced radially outwardly from the shaft and an opposed non-cylindrical exterior surface. At least one aperture extends through the skirt. A locking spring is disposed adjacent the interior surface of the skirt and includes a locking detent extending through the aperture in the skirt. The spring can be deflected radially inwardly to bring the detent into alignment with the exterior surface of the skirt. A reamer head is mountable over the mounting cap such that the rear wall of the reamer head deflects the spring radially inwardly during mounting and unmounting. In the fully mounted condition of the reamer head, the locking detent of the spring engages an inwardly facing surface of the rear wall of the reamer head. The.degree.

Abstract: A multi-component hip joint prosthesis is provided comprising an acetabular cup and a plastic bearing liner, each of which defines a segmented open shell with an inferior segment thereof removed to provide enhanced flexibility. The enhanced flexibility substantially facilitates the assembly and disassembly of the components. The liner and the cup are retained in their assembled condition by interengagement between a plurality of ridges and at least one groove on the respective components. The plurality of independent ridges enhances the flexibility of the ridges, thereby further minimizing the assembly forces required. Interengageable keys and keyways on the respective components may be provided to prevent relative rotation therebetween. The cup may comprise a removable tab to facilitate the insertion of a tool between the cup and the liner for prying the liner from the cup if necessary.

Abstract: A surgical saw having a base blade portion, a plurality of staggered teeth and an intermediate blade portion, the thickness of which is less than the thickness of the base blade portion. The thickness of the intermediate blade portion is sufficiently less than the thickness of the base blade portion to permit passage of bone cuttings and other material away from the staggered teeth during operation of the surgical saw.

Abstract: A prosthetic joint includes a first bearing element which is attached to a first bone and has a substantially flat bearing surface. A second element having a bearing surface is attached to a second bone. A bearing is disposed between the first and second elements. The bearing has a central axis and is defined by a first surface and a second surface. The first surface is substantially flat and is at least partially in contact with the first flat surface of the first element. At least a portion of the second surface is in contact with the surface of the second element. The area of the planform of the first surface of the bearing is smaller than, and dissimilar in shape from, the area of the planform defined by the second surface of the bearing.