Abstract: A centralizer for the stem of a cementable prosthetic orthopedic implant that is implanted into the medullary canal of a bone has a hollow annular body with a tapered interior surface for receiving a tapered stem of the implant. The centralizer has four fins spaced around the exterior surface of its annular body with the fins extending radially outwardly in a direction generally perpendicular to the longitudinal axis extending along the stem in a proximal-distal direction. The annular body of the centralizer has a proximal and a distal end surface spaced a predetermined distance apart with the fins having a base adjacent the body extending over a substantial portion of the predetermined distance. Adjacent fins are offset from neighboring fins in a proximal-distal direction so that when the proximal-distal dimension of the annular body is maintained, it generates a wavelike structure for the centralizer body.

Abstract: A method and apparatus for preparing a planar surface on the distal femur prior to implantation of a femoral knee prosthesis has a femoral plate with an opening therein for exposing both condyles of the femur. A guide with a central aperture is used to align the femoral plate on the distal femur. The guide is releasably secured to the femoral plate and an intramedullary guide rod is placed through the aperture therein and into the intramedullary canal of the femur. After alignment with the intramedullary canal, the femoral plate is pinned to the femur and the rod and guide are removed. A milling guide having two bores, one adjacent each condyle, is then placed on the femoral plate and an end mill is used to mill a planar surface on at least one of the condyles.

Abstract: A medical implant made of polymeric material having an increased oxidation resistance is formed by a method including the steps of placing a resin powder in a sealed container. A substantial portion of the oxygen is removed from the sealed container by either a vacuum, an oxygen absorbent or by flushing with inert gas. The container is then repressurized with a gas such as nitrogen, argon, helium or neon so that long term storage may be possible. On use, the resin is transferred to a forming device which both melts and forms the resin in an oxygen reduced atmosphere to produce a polymeric raw material such as a rod or bar stock. The medical implant is then formed from this raw material annealed and sealed in an air-tight package in an oxygen reduced atmosphere. The implant is then radiation sterilized and thereafter annealed in the package for a predetermined time and temperature sufficient to form cross-links between any free radicals in neighboring polymeric chains.

Abstract: A device for stabilizing a long bone combines an external fixator with a locking nail implanted in the medullary canal of a long bone. The external fixator has fixed bone pins at each of its ends and movable bone pins intermediate its ends. The fixed bone pins extend through transverse bores at each end of the bone nail and the movable pins extends through a slot in the bone nail intermediate its ends. By this method a fracture can be compressed and stabilized while healing.

Abstract: An acetabular bone graft impactor comprising a contact surface at least part of which is located on a head connected to a shaft provided with and anvil to be hit with a hammer. A flange extends from the head so that the contact surface shape can be selectively altered.

Abstract: A prosthetic patello femoral joint assembly comprises a patella mounting component on which is located a movable mobile bearing component. A first side of the bearing component is shaped to engage the patella groove of a natural or an artificial femur. A second side of the mounting component has a substantially spherical convex bearing surface which engages and can articulate against a substantially spherical posterior concave bearing surface on the mounting component. A control means acts between the components to restrict substantially vertical movement of the bearing component about a medio lateral axis of the knee with which it is to be used, but allows substantially horizontal movement and relative rotation between said mounting component and said bearing component.

Abstract: An acetabular cup for a total hip prosthesis has an outer shell and an inner bearing component. The shell is molded around the inner bearing component and has an elastic modulus similar to subchondral bone of between 5 GPa and 18 GPa. The shell has a part-spherical main portion and two independent arms projecting from the part-spherical main portion. The arms are separated from each other by an opening of predetermined shape and size.

Abstract: A surgical instrument system for preparing the medullary canal of the femur for implanting a prosthetic femoral component includes a template to be used in determining osteotomy position from an x-ray. A gauge is provided to locate and mark this position on the anterior femur. A distal reamer having an elongated drive shaft is used to form the canal to receive the distal stem of the femoral component. A metaphyseal template is used to determine the proper anteversion/retroversion and a chisel is used to cut the lateral area of the femur, both of which are guided by the elongated reamer shaft. A proximal broach also guided by the reamer shaft is used to shape the proximal medullary canal.

Abstract: A femoral hip component for use in hip arthroplasty has a stem portion for contact with bone cement. The stem portion is formed from a biocompatible material having a surface finish of less than about four microinches. This surface is coated with a uniform layer of material selected from the group consisting of diamond-like carbon, chromium carbide, titanium nitride, titanium carbo-nitride, chromium and zirconium and a combination thereof.

Abstract: A medical implant made of polymeric material having an increased oxidation resistance is formed by a method including the steps of placing a resin powder in a sealed container. A substantial portion of the oxygen is removed from the sealed container by either a vacuum, an oxygen absorbent or by flushing with inert gas. The container is then repressurized with a gas such as nitrogen, argon, helium or neon so that long term storage may be possible. On use, the resin is transferred to a forming device which both melts and forms the resin in an oxygen reduced atmosphere to produce a polymeric raw material such as a rod or bar stock. The medical implant is then formed from this raw material annealed and sealed in an air-tight package in an oxygen reduced atmosphere. The implant is then radiation sterilized and thereafter annealed in the package for a predetermined time and temperature sufficient to form cross-links between any free radicals in neighboring polymeric chains.

Abstract: A method of implanting an acetabular cup includes preparing an acetabular socket to receive said cup, placing cement in said socket before or after locating a loading tube in line with the socket and inserting the acetabular cup through the tube into said socket. This is done by pushing it down the tube with an inserter to a predetermined position therein defined by a stop element acting on the inserter or an attachment thereto.

Abstract: An orthopaedic implant comprising a cast metal base member having an outer surface and an ingrowth surface comprising a plurality of attachment spacer elements of unequal lengths integrally cast with said base member and a metal attachment element integrally cast with said spacer elements, said attachment element having connecting elements extending between said spacer elements to allow attachment of the bone to occur between an underside of said connecting elements and the outer surface of said base member. The invention also consists of a method for preparing such an implant, wherein the spacer elements are of equal or unequal length, which comprises inserting a preformed ceramic pattern for the ingrowth surface into a die for the implant, injecting a meltable material in its molten state into the die at a temperature below the melting temperature of the ceramic to fill the holes and grooves of the pattern.

Abstract: A femoral component of a replacement hip joint has a collarless stem including a shoulder for fixing in a medullary canal by cement. The component has a stem beneath the shoulder having a straight taper and the anterior and posterior faces of the stem each having a concave surface formed by a longitudinally extending curve from the top of the shoulder to the distal tip of the stem.

Abstract: An orthopedic instrument for guiding a saw blade for preparing the distal end of a human femur to receive an endoprosthetic femoral component has a base component provided with guide for guiding cutting blades. The guide can be used to shape all of the necessary femoral surfaces to receive the femoral component to be fitted once the base component is fitted to the bone. A device for aligning the base component on the bone elements for attaching the base component to the bone after alignment is also provided.

Abstract: A medical implant made of polymeric material having an increased oxidation resistance is formed by a method including the steps of placing a resin powder in a sealed container. A substantial portion of the oxygen is removed from the sealed container by either a vacuum, an oxygen absorbent or by flushing with inert gas. The container is then repressurized with a gas such as nitrogen, argon, helium or neon so that long term storage may be possible. On use, the resin is transferred to a forming device which both melts and forms the resin in an oxygen reduced atmosphere to produce a polymeric raw material such as a rod or bar stock. The medical implant is then formed from this raw material annealed and sealed in an air-tight package in an oxygen reduced atmosphere. The implant is then radiation sterilized and thereafter annealed in the package for a predetermined time and temperature sufficient to form cross-links between any free radicals in neighboring polymeric chains.

Abstract: A beam adapted for implantation within a bone is able to support bending and torsional loading forces applied thereto. The beam has a stiffness defined by a modulus elasticity, which stiffness varies along the length of the beam to match the corresponding stiffness of the cortical bone adjacent the beam after implantation within the bone. The beam is made from an elongated core formed of chopped carbon fibers embedded in a thermoplastic polymer matrix. Encasing the core is a sheath formed of carbon reinforced filament fibers embedded in the thermoplastic polymer which is wound in spiral formation around the core and molded thereto. The winding angle and the sheath thickness along the beam may be varied to vary the modulus of elasticity to match that of the cortical bone adjacent thereto.

Abstract: An improved metallic bone prosthesis having a porous coating for bone ingrowth or interlocking with bone cement is disclosed. The porous coating comprises two layers of generally ball-shaped metallic particles bonded together at their points of contact, e.g. by sintering, and defining between them a plurality of connected interstitial pores having an average pore size of from about 350 microns to about 500 microns. A high resistance to failure at the coating-substrate and bone-coating (or cement-coating) interfaces is achieved with the use of the improved prosthesis. Also disclosed are a novel method for affixing the porous coating to a metal substrate, and a knee joint prosthesis having bearing portions designed so that the function of said prosthesis closely approximates that of the natural knee.

Abstract: An acetabular cup for use as a prosthetic implant has an insert with a body including a central bore for receiving a positioning rod therein. A key element is formed on the bore and is adapted to align the positioning rod. The insert has a locating element formed on an outer surface of the body and also includes spring elements extending radially outwardly from the body. The acetabular cup has a generally hemispherical shell member coupled to the outer surface of the insert. The shell has an outer surface for engaging the acetabulum and an inner surface having a circumferential groove for receiving the spring elements. The spring elements may be deflected radially inwardly out of engagement with the groove for releasing the insert from the shell. The spring elements can be deflected by pushing a sleeve down the rod to make contact with and deflect the spring element.

Abstract: A method and apparatus for preparing a planar surface on the distal femur prior to implantation of a femoral knee prosthesis has a femoral plate with an opening therein for exposing both condyles of the femur. A guide with a central aperture is used to align the femoral plate on the distal femur. The guide is releasably secured to the femoral plate and an intramedullary guide rod is placed through the aperture therein and into the intramedullary canal of the femur. After alignment with the intramedullary canal, the femoral plate is pinned to the femur and the rod and guide are removed. A milling guide having two bores, one adjacent each condyle, is then placed on the femoral plate and an end mill is used to mill a planar surface on at least one of the condyles.

Abstract: A medical implant made of polymeric material having an increased oxidation resistance is formed by a method including the steps of placing a resin powder in a sealed container. A substantial portion of the oxygen is removed from the sealed container by either a vacuum, an oxygen absorbent or by flushing with inert gas. The container is then repressurized with a gas such as nitrogen, argon, helium or neon so that long term storage may be possible. On use, the resin is transferred to a forming device which both melts and forms the resin in an oxygen reduced atmosphere to produce a polymeric raw material such as a rod or bar stock. The medical implant is then formed from this raw material annealed and sealed in an airtight package in an oxygen reduced atmosphere. The implant is then radiation sterilized and thereafter annealed in the package for a predetermined time and temperature sufficient to form cross-links between any free radicals in neighboring polymeric chains.