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 patella milling instrument has a planar base with a fixed patellar clamping element formed thereon. A movable patellar milling element is slidably mounted on the base and is movable towards and away from the fixed clamping element. A drive element is operable between the base and the movable element for moving the movable clamping element. The drive element is actuated by a drive mechanism fixed in a handle of the device found at one end thereof and connected to a drive element which is also in the form of a ratchet element. A movable end mill type cutting element is mounted on a support arm supported by the base. The support arm is capable of movement in directions parallel to the plane of the base and is adjustable in a direction perpendicular to the base. The end mill has a drive shaft rotatably mounted in a bushing in an end of the support arm which drive shaft is rotatable by a power tool and capable of movement in a direction perpendicular to the plane of the base.

Abstract: A method of dehydration of bulky hydrogel samples of polyvinyl alcohol (i.e., PVA) and a method of preparation of prosthetic nuclei for vertebral discs are given. A method of gamma irradiation sterilization of PVA gel samples which does not incur the side effects of discoloration and of increased crystallinity (i.e., further reduction of water content) is also given.A method of dehydrating bulky hydrogel samples of polyvinyl alcohol (i.e., PVA) so that no significant distortion in the samples results, comprises:(a) subjecting the sample to a solvent system comprising at least one organic solvent which(1) has a solubility for PVA which is less than the solubility of water for PVA and(2) is miscible with waterfor a length of time generally from about 2 to about 10 days so that the dehydration rate of the hydrogel samples is sufficiently slow so as not to cause any distortions on the dehydrated samples.

Abstract: An improved surgical broach for preparing an intramedullary canal of a bone for receiving a prosthesis is described, wherein the broach comprises a plurality of cutting teeth having different configurations and placement upon the broach for optimizing cutting efficiency and speed for improved surgical ease-of-use while minimizing gap formation between the prosthesis and the intramedullary canal.

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 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 ratcheting compression device is provided which is very strong, which can be customized in length, which can be retightened periodically to maintain compression, which allows precise placement and alignment of bones with both grossly tuned compression and finely tuned compression, and in which only a limited inventory of parts is required. The two-piece compression device comprises (a) a novel first piece having a bone screw located at a first end thereof and having a ratcheting member located near the second end thereof and comprising teeth having their crests lying substantially in a plane and (b) a novel second piece comprising an anti-rotation member which acts in cooperation with the ratcheting member of the first piece to compress two segments of bone together. In yet other embodiments, two embodiments of a driver are provided for quickly driving the stop onto the ratcheting member to a desired extent.

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 multi-piece trial femoral component kit for use in sizing a femoral cavity prior to implantation of a prosthetic femoral implant. The trial femoral component kit has at least two distal trial components of different size and two proximal trial components of different size and mating elements which allow the proximal and distal components to be releasably coupled to form a femoral trial prosthesis. The distal trial component combines with the proximal trial component to form the stem of the femoral trial prosthesis, the joint of the two components located in the circumferential area between the gluteal tuberosity and about 2" below the pectineal line of the femur when the femoral trial is inserted within the femur. The distal and proximal components may further include means for selectively combining the proximal and distal components to form a femoral trial prosthesis that corresponds to an available prosthetic femoral implant.

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 device for bending a plate with an offset distance L and two angles simultaneously is provided, the device comprising special jaws which are replaceably attachable to the jaws of a pliers. A kit of a plurality of sets of bending jaws having a variety of offset lengths is provided.

Abstract: An awl suitable for both opening up a bone canal and for sizing that bone canal so as to obviate the use of a Charnley awl and the use of 4 to 5 distal reamers comprises (a) a tapered distal cutting head having a pointed first end, and a second end; and (b) a shaft attached to the second end, such that the shaft has a multiplicity of grooves calibrated so as to indicate the diameter of the isthmus of the bone canal. Also provided is a method of opening up a bone canal and of measuring the diameter of the isthmus of the bone canal with a single instrument.

Abstract: A femoral hip prosthesis comprises a main member, a modular member and a means for connecting the two. The main member has a stem portion and a body portion which are adapted for insertion into the intramedullary canal. The body portion has lateral, posterior, and anterior sides adapted to mate with the bone and has a medial side configured and dimensioned to receive a modular member. The modular member is chosen from a plurality of such members of various shapes and sizes and is adapted to fit accurately into the intramedullary canal, especially after the intramedullary canal has been deformed through the prior implantation of a prosthetic hip device.

Abstract: A prosthesis with an integral proximal spacer is described. The prosthesis has a base element with a textured surface to aid in adhesion to bone cement. The integral spacer has a generally tripod shape. A top circumferential portion at least partially surrounds the proximal end of the prosthesis, and three legs extend distally along the length of the prosthesis. Also disclosed is the process for making the prosthesis and spacer, which preferably involves injection molding of PMMA.

Abstract: Methods and apparatus are set forth for preparing and delivering bone cement from a powdered polymer component and a liquid monomer component by simultaneously injecting the powdered and liquid components, stored in separate component chambers, into an evacuated mixing chamber under the effect of the vacuum; by uniformly mixing the components in the mixing chamber (to thoroughly wet the powder); and by delivering the cement formed by the polymerization process, as needed in an operative setting, utilizing a single ready to use device. The uniform mix is achieved by simultaneously subjecting the contents of the component chambers to the effects of the mixing chamber's vacuum via separate one way nozzles, interconnecting the component chambers to the mixing chamber, which cause the powder to be broadcast and liquid to be sprayed into the mixing chamber.

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: An osteotomy cutting guide is disclosed. The cutting guide utilities an angle cutting block which is removably and adjustably attached to a stabilizing base. Also utilized is a distal hole drill block which is removably and adjustably attached to the stabilizing base. The stabilizing base has at least one projecting element which can be inserted into an existing cut. The osteotomy cutting guide allows angled cuts and implant insertions to be performed with accuracy.

Abstract: A prosthetic nucleus for a vertebral disc is made of a hydrogel material. The hydrogel prosthetic nucleus has a shape generally conforming to the natural nucleus pulposus, and it exhibits diminished lateral bulging under high compressive loads. The hydrogel has a water content of from 30% to 90% and has a compressive strength of 4 MNm.sup.-2 or greater. When the hydrogel material is dehydrated, it has a dimension of less than half of that of the hydrated hydrogel nucleus. The prosthetic nucleus may be formed of two or more pieces of hydrogel material which pieces, when combined, have a shape generally conforming to the natural nucleus. The prosthetic nucleus may have a stiff posterior periphery and/or a thickened anterior wall.

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: Novel prosthetic nuclear implants for insertion into vertebral discs are prepared by dehydrating hydrated bulky hydrogel discs under specific conditions so as to reduce the water content as low as possible (down to about 10% by weight) but without distortion of the implants, without the formation of concavities and sharp edges, and without changing the shape of the hydrated implant.