Abstract: Orthopedic implants which includes the components of zirconium or zirconium-based alloys having surfaces coated with oxidized zirconium or alternatively, other orthopedic implants comprising abrasion resistant surfaces contacting surfaces of cross-linked polyethylene are disclosed. Such implants provide low friction, highly wear resistant coatings especially useful in artificial joints, such as hip joints, knee joints, elbows, etc., but also useful in other implant devices as well.

Abstract: This application provides a novel unitary bone implant having at least one rigid, mineralized bone segment, which may be machined to include threads, grooves, a driver head, perforations, a recess, or a symmetric shape, and a flexible, demineralized segment, which may also be machined to any desired shape prior to demineralization, or after demineralization. The disclosed implant has wide orthopedic applicability, including but not limited to repair or replacement of ligaments, tendons, and joints and for inducing vertebral fusions and fractured bone repair.

Abstract: Artificial implants having reduced area to provide reduced wear are provided. The reduced area is particularly located at areas where greatest wear is exhibited. In a particular embodiment of a mobile bearing knee implant, the area is reduced on the mobile bearing insert underside, where it contacts a tibial component. The reduced area may be any shape of indentations, for example, grooves, dimples, straight patterns, curved patterns, crossing patterns, holes, channels or slots. The indentations may be various sizes, and have been found to be particularly effective if covering about 10% to about 20% of the insert at depths between about 1-2 mm.

Abstract: A spacing device for supporting a joint adjacent to diseased bone or missing bone tissue, comprising a support piece and a semi-resilient pad. The pad is shaped to cradle and support the healthy bone joint. The reverse side of the pad is fixedly connected to one end of the support piece. The other end of the support piece is shaped to straddle healthy tissue adjacent the damaged area, such as the ilium when supporting a hip joint and is to be fixedly connected to the adjacent healthy tissue, using a suitable mechanism, such as biocompatible Steinman pins. Diseased, damaged, or necrotic tissue can be removed without requiring removal of the natural bone joint. Because the undamaged bone joint is not replaced, the problems commonly experienced during and following bone joint replacement are avoided. In particular, blood loss during surgery, surgical cost, surgical time, and rehabilitation of the patient after surgery is reduced.

Abstract: A joint implant, which is not itself a femoral component for a conventional hip joint replacement prosthesis having a diamond or diamond like coated ball, has a diamond or diamond like coated articulating surface. The coating can be transitional in nature. The implant can be based on a suitable support material, for example, a metal, a ceramic, or a plastic, with the support material being coated with the diamond or diamond like substance. The implant may be, for instance, for a ginglymous type, an enarthrodial type, or a digital joint. Convex and/or concave articulating surface(s) of a prosthesis can have the coating.

Abstract: A prosthetic implant system connected to the tissue of a living organism. The system contains a first device for measuring the mechanical strain in the implant in an area thereof which is not exposed to tissue regrowth, a second device for measuring the mechanical strain in the implant in an area thereof which is exposed to tissue regrowth, a device for continuously determining the stress/strain relationship of said implant, and a device for treating said tissue.

Abstract: Prosthetic joints, components for prosthetic joints, superhard bearing and articulation surfaces, diamond bearing and articulation surfaces, substrate surface topographical features, materials for making joints, bearing and articulation surfaces, and methods for manufacturing and finishing the same, and related information are disclosed, including a prosthetic joint having substrate surface topographical features and at least one diamond articulation surface.

Abstract: This invention relates to a prosthetic element comprising two principal components intended to be assembled together and immobilized with respect to each other by means of a screw, which may be screwed by means of at least one thread in two tappings which are respectively fast or intended to be rendered fast with one and the other principal components. The screw comprises at least one radial element in relief adapted to come into abutment against a stop surface fast with a first component, and a non-threaded end forming guide finger and adapted to slide in a housing, of cross-section correspondiong to that of this finger and made in the second component.

Abstract: A long bone prosthesis includes upper and lower articulating components, with the free ends of the components configured to engage a corresponding prosthetic joint. The overall length of the articulating components is adjustable to approximate the length of a patient's long bone, such as the humerus. The articulating components include a stem and collet arrangement for fixing the relative axial and rotational position of the components. A tapered lock nut is threaded onto the outer threaded surface of the collet portion to provide a pressure engagement of the articulating elements. Various surface features can be implemented among the components of the prosthesis to enhance the pressure fixation, restrict rotation or provide indexed movement of the articulating components relative to each other.

Abstract: A joint surface replacement or joint prosthesis for the distal radioulnar (DRU) joint. A complete surface replacement comprises two parts, a radial component (1) and an ulnar component (2), both of which are designed to be inserted radially relative the radius (6) and the ulna (7). The radial (1) and ulnar (2) components are constructed to assure that the concave surface of the radial component may be pivoted and translated around the convex surface of the ulnar component during rotational movement of the forearm. Either component may be singularly implanted when there is no deterioration of the mating component. By providing these components in a range of thicknesses and lengths, more effective stabilization of such joint is possible.

Abstract: The present invention relates to a method and instrumentation for gaining access to areas in and around joints for treatment and to provide new implants and instrumentation adapted for the new method. In a transosseous core approach of the present invention, the joint is entered through a pathway provided in a portion of a joint bone. Such pathway is preferably made by taking out a bone core from the bone in or adjacent to the joint, wherever possible without substantially compromising physical integrity and physiological viability of the joint. Typically the main route for the transosseous core approach traverses through a more-accessible bone of the joint which can be aligned with a less-accessible bone of the joint in order to facilitate treatment of articular surfaces and/or other structures in the joint. The transosseous pathway into the joint is preferably provided by novel surgical instruments such as a core cutter, cartilage punch, hemostatic device, and retractable axial/transaxial cutting device.

Abstract: A textured surface and oxidation layer coating on a metallic material is accomplished through the chemical and/or electrochemical etching of the surface to modify the surface texture and an in-situ oxidation procedure. The surface is useful for the fabrication of prosthetic devices, particularly medical implants, due to the corrosion and wear resistance imparted by the oxidation layer and the ability to enhance grafting of the implant onto bone imparted by the surface texture.

Abstract: A medical implant having at least a portion thereof made of a formable, pyromellitic, dianhydride (PMDA)-free, non-halogenated, aromatic polyimide is disclosed. Further disclosed are a process of manufacturing the implant and a method of implanting the implant in a subject in need thereof.

Abstract: Material compositions for use in orthopedic implants comprising blends of ultra high molecular weight polyethylene (UHMWPE) and hard ceramic powders prepared by blending powdered UHMWPE and the ceramic powder in a high shear mixer are described. Orthopedic implants are then fabricated by pressure/thermo-forming the ceramic/polymer blend into a net shape prosthesis or a rod suitable for subsequently machining the desired components using diamond tooling. Net shape forming is the preferred method for preparing the orthopedic implants.

Abstract: A prosthetic joint in an embodiment has two load-bearing surfaces that are slidingly disposed relative to each other and define a region of frictional contact. The joint is thermally managed as heat is removed from the region during joint use by thermal conduction so that the surfaces are maintained approximately at or below specified temperatures. In other embodiments, heat flows preferentially through one member which includes one of the surfaces. Use of high thermal conductivity materials in conjunction with various joint designs affording thermally managed devices are provided in numerous embodiments.

Abstract: The present invention relates to the prevention and decrease of osteolysis produced by wear of the ultrahigh molecular weight polyethylene (UHMWPE). Methods are disclosed for the isolation of wear particles, preparation of implants exhibiting decreased wear in comparison to conventional UHMWPE and preparation of implants that cause decreased biological response in comparison to conventional UHMWPE. The implants created by these methods are also included in the present invention.

Abstract: A joint prosthetic component that includes first and second arms, and a joint member interposed therebetween. The joint member is configured to permit flexion motion between the first and second arms, and includes a first concave surface and a second concave surface. The first concave surface has a plurality of arcuate portions defined therein. The first and second concave surfaces are located on opposing sides of the joint member.

Abstract: A teletibial implant is provided for measuring forces between a femur having first and second condylar surfaces and a tibia when a joint is articulated. The implant includes a medial tibial insert engaging the first condylar surface and a lateral tibial insert engaging the second condylar surface. A transducer includes a medial plate coupled to the medial tibial insert, a lateral plate coupled to the lateral tibial insert, and a bottom plate supporting the medial and lateral plates. The medial and lateral plates receive forces from the medial and lateral inserts, respectively. The bottom plate also has a plurality of spaced apart force sensors for measuring forces exerted on the medial and lateral plates.

Abstract: The invention relates to joint prosthesis elements, to a method of manufacturing prostheses, and to a kit for putting said prostheses into place. The prosthesis element which is put into place in a resection in the joint surface is defined by a contact surface C, a fixing surface F and, interconnecting said surfaces, a peripheral surface P which co-operates with a projecting rim R of the resection. An anchoring element A projects from the fixing face and penetrates into a corresponding anchoring hole D.

Abstract: An alignment verification device includes a spacer element and an alignment guide surface. The spacer element has proximal and distal portions and an insert engaging element disposed on the distal portion. The proximal portion can be of such a designed so as to serve as a handle for the verification device. The alignment guide surface is affixed to the spacer element and defines an alignment orifice. The alignment orifice is spaced apart from the insert engaging element. A prosthesis is also disclosed having an engaging element and a visual indicator element. The engaging element is configured to releasably engage the prosthesis engaging element of the alignment verification device so that, upon engagement, the alignment orifice is spaced apart from the visual indicator element.

Abstract: The present invention provides a biomedical implant material comprising a substrate for biomedical implant made of a ceramic material, a first coating layer formed on the surface of said substrate by low-thermal impact coating process, and a second coating layer formed on said first coating layer via a metallic layer formed by thermal spraying process, and a method of producing the same. According to the biomedical implant material, it is made possible to prevent cracks from occurring in the ceramic substrate, and to secure sufficient bonding strength between the thermal-sprayed layer of titanium or the like onto the ceramic substrate.

Abstract: A load-sharing resorbable scaffold is used to help transplanted chondrocytes or other cells generate new cartilage in a damaged joint such as a knee, hip, or shoulder. These scaffolds use two distinct matrix materials. One is a relatively stiff matrix material, designed to withstand and resist a compressive articulating load placed on the joint during the convalescent period, shortly after surgery. Due to the requirement for relatively high stiffness, this material must be denser and have less pore space than other matrices, so it will not be able to support highly rapid cell proliferation and cartilage secretion. The second material comprises a more open and porous matrix, designed to promote maximal rapid generation of new cartilage. In one preferred geometric arrangement, the stiffer matrix material is used to provide an outer rim and one or more internal runners, all of which can distribute a compressive load between them.

Abstract: An orthopaedic hip demonstration aid for demonstrating the fitting of an orthopaedic prosthesis to a human skeletal hip comprises a facsimile femur part including an elongate main portion incorporating an axial passage and consisting of two detachable parts secured together by magnetic attraction and received within the passage, and a detachable sheath portion consisting of two detachable parts secured together by magnetic attraction and received within the parts. The parts define a further axial passage adapted to detachably receive a shaft of the prosthesis such that a head of the prosthesis projects from an end of the femur part. Such an orthopaedic hip demonstration aid may be used to demonstrate surgical orthopaedic techniques in hip replacement.

Abstract: Regardless of the materials used in an artificial joint component design, the present invention applies gas cluster ion beam (GCIB) technology in order to modify the component's surface(s) so as to increase lubrication between contact surfaces, thereby substantially reducing wear debris, osteolysis complications, and accelerated wear failure. The approach of the surface modification comprises an atomic level surface patterning utilizing GCIB to apply a predetermined pattern to the surface(s) of the joint implant to reduce frictional wear at the interface of the surfaces. A reduction in wear debris by GCIB patterning on any surface(s) of a joint prosthesis reduces accelerated failure due to wear and osteolysis and results in a substantial cost savings to the healthcare system, and reduces patient pain and suffering.

Abstract: Prosthetic joints, components for prosthetic joints, superhard bearing and articulation surfaces, diamond bearing and articulation surfaces, substrate surface topographical features, materials for making joints, bearing and articulation surfaces, and methods for manufacturing and finishing the same, and related information are disclosed, including a component for use in a prosthetic hip, the component having a polycrystalline diamond articulation surface and a plurality of substrate layers.

Abstract: A method for improving the wear resistance of an implant, made of polyethylene, by crosslinking its bearing surface layer, while leaving its non-bearing interior uncrosslinked. Such crosslinking may be achieved by electron-beam irradiation or by chemical crosslinking of the implant or the polyethylene from which the implant is made. The resulting implant or polyethylene may be further treated to remove the residual free radicals (generated by the electron beam crosslinking process); to remove residual chemicals (generated by the chemical crosslinking process); to remove its most oxidized layer; to stabilize its size and shape; to improve, by remelting, its oxidation resistance; and/or to reshape it into the final implant. Also presented are the resulting implant and polyethylene.

Abstract: This invention relates to a surgical implant which contains a relatively soft component, such as a hydrogel or gel-like component, that is affixed to a harder and stiffer material. One such implant is designed to replace a segment of damaged cartilage in a knee, hip, shoulder, or other joint. Instead of attempting to bond a gel-like material to a hard surface with a relatively flat interface, this improved device provides a “multi-perforated non-planar” (MP/NP) interface between the two types of material. This type of MP/NP interface can provide a stronger and more durable gel structure, and it can enable the water molecules in the gel component to disseminate and distribute compressive and shear loads in a more even manner, reducing the risk of tearing or other damage.

Abstract: A hip joint prosthesis having a retainer for a modular bearing in an acetabular cup and also having a bearing extraction member mounted in the cup for removal of a primary bearing. One embodiment of the bearing extraction member is a plug which is located in a hole provided in the acetabular cup and which is covered by a polyethylene bearing directly molded into the cup. The plug is an internally threaded plug with a convex head and is adapted to be pulled out of its resting position in the cup with the aid of an extraction tool such that the head of the plug exerts a removal force on the molded polyethylene bearing, causing it to disengage from the cup.

Abstract: A prosthetic ankle joint consisting of an upper housing (1) and a lower housing (2) which are connected to and rotate about a shared axis (3). A plurality of motion members (5) are utilized to control the motion of the ankle joint through weight-bearing and non weight-bearing conditions. The presence or absence of an adjustable anterior element (12) and posterior element (13) will dictate the allowable relative motion of the lower housing to the upper housing. The upper receptacle (4) allows the ankle to be attached to a tube clamp adapter (15) and pylon (8). The lower receptacle (14) allows for the rigid attachment of a prosthetic foot (16).

Abstract: An apparatus for modeling a skeletal structure before and after a surgical procedure is performed on the structure. The apparatus comprises a base, the base including a generally planar surface, at least one bone member coupled to the base, the bone member representing a bone involved in the surgical procedure, and at least one bone portion movably coupled to the bone member, the bone portion representing a part of the bone involved in the surgical procedure that is repositioned in the surgical procedure from a preoperative position to a postoperative position. The bone portion may be selectively moved between a preoperative position, representing the position of the part of the bone before the surgical procedure is performed, and a postoperative position, representing the position of the part of the bone after the surgical procedure is performed. The bone member may be coupled to the base generally parallel to the surface of the base.

Abstract: The present invention relates to a method and instrumentation for gaining access to areas in and around joints for treatment and to provide new implants and instrumentation adapted for the new method. In a transosseous core approach of the present invention, the joint is entered through a pathway provided in a portion of a joint bone. Such pathway is preferably made by taking out a bone core from the bone in or adjacent to the joint, wherever possible without substantially compromising physical integrity and physiological viability of the joint. Typically the main route for the transosseous core approach traverses through a more-accessible bone of the joint which can be aligned with a less-accessible bone of the joint in order to facilitate treatment of articular surfaces and/or other structures in the joint. The transosseous pathway into the joint is preferably provided by novel surgical instruments such as a core cutter, cartilage punch, hemostatic device, and retractable axial/transaxial cutting device.

Abstract: A method, and related composition and apparatus for repairing a tissue site. The method involves the use of a curable polyurethane biomaterial composition having a plurality of parts adapted to be mixed at the time of use in order to provide a flowable composition and to initiate cure. The flowable composition can be delivered using minimally invasive means to a tissue site and there fully cured provide a permanent and biocompatible prosthesis for repair of the tissue site. Further provided are a mold apparatus, e.g., in the form of a balloon or tubular cavity, for receiving a biomaterial composition, and a method for delivering and filling the mold apparatus with a curable composition in situ to provide a prosthesis for tissue repair.

Abstract: The implant has at least one contact surface portion, made of pyrolytic carbon, designed to be in mobile contact with at least one bony surface when the implant is implanted in a patient. Furthermore, the implant is free from any attaching means, so that it remains free with respect to the at least one bony surface when implanted in the patient.

Abstract: Methods and compositions for fabricating prosthetic medical devices exhibiting improved wear resistance include selectively cross-linking polymeric resins then curing and shaping the polymer into a finished article. The selectively cross-linked polymeric compositions may be created by blending a specific amount of cross-linked resins with a specific amount of uncross-linked resins then cured into a polymeric matrix whereby the desired degree or percentage of overall cross-linking is obtained. The polymeric material may then be formed directly into a finished article by injection molding the polymeric material.

Abstract: A non-elastomeric polyurethane composition which includes a first chain extender of the general formula (I) wherein R1, R2, R3, R4, R5, and R6 are the same or different and selected from an optionally substituted straight chain, branched or cyclic, saturated or unsaturated hydrocarbon radical; R7 is a divalent linking group or an optionally substituted straight chain, branched or cyclic, saturated or unsaturated hydrocarbon radical; and n is 0 or greater, and a second chain extender.

Abstract: Pairs of partner elements for artificial joint implants have two-dimensional surface contact in which one joint part (1) rotates, rolls, slides or combines these in one movement relative to another joint part (2). A gap (10) is formed between the sliding partner elements for a film consisting of natural synovia fluid. The surface of at least one of the sliding partner elements has regularly positioned recesses (3) which serve as a reservoir for the synovia.

Abstract: Prosthetic joints, components for prosthetic joints, superhard bearing and articulation surfaces, diamond bearing and articulation surfaces, substrate surface topographical features, materials for making joints, bearing and articulation surfaces, and methods for manufacturing and finishing the same, and related information are disclosed, including a prosthetic hip joint having polycrystalline diamond articulation surfaces and at least one sintered polycrystalline diamond articulation surface.

Abstract: Prosthetic joints, components for prosthetic joints, superhard bearing and articulation surfaces, diamond bearing and articulation surfaces, substrate surface topographical features, materials for making joints, bearing and articulation surfaces, and methods for manufacturing and finishing the same, and related information are disclosed, including a prosthetic joint having at least one superhard articulation surface.

Abstract: A prosthetic ankle joint consisting of an upper housing (1) and a lower housing (2) which are connected to and rotate about a shared axis (3). A plurality of motion means (5) are utilized to control the motion of the ankle joint through weight-bearing and non weight-bearing conditions. The presence or absence of an adjustable anterior element (12) and posterior element (13) will dictate the allowable relative motion of the lower housing to the upper housing. The upper receptacle (4) allows the ankle to be attached to a tube clamp adapter (15) and pylon (8). The lower receptacle (14) allows for the rigid attachment of a prosthetic foot (16).

Abstract: A prosthetic joint and related placement method are provided for cemented fixation to a prepared patient bone, with a cement layer and mantle of controlled, predetermined thickness. The prosthetic component such as a tibial or femoral component for a knee prosthesis includes an attachment surface bounded by a flow restrictor wall which cooperates with the attachment surface to define an open-sided cavity for receiving a quantity of bone cement. An intruder tool is provided to form a shallow recess in the prepared patient bone for mating seated reception of the flow restrictor wall on the prosthetic component. In one form, the prosthetic component and the intruder tool may be adjustable to fit patient bones of different size.

Abstract: A method of promoting regeneration of surface cartilage of a joint includes the steps of forming punctures in a subchondral plate of an area of the joint to be treated, covering the puncture and the area to be treated with a chondrocyte-free patch made of a sheet of collagen membrane material without adding chondrocytes to the area to be treated, fixing the patch over the area to be treated, and allowing the area to be treated to regenerate cartilage without adding chondrocytes to the area to be treated.

Abstract: A prosthesis structure (1) for anchorage to the joint end of an articulatory part of a joint (11) in a human or animal body comprises an engagement element (3) which presents a flat or substantially flat engagement surface (3b) for engaging with a complementary joint end surface (14) provided at the joint end and an elongate fixture (4) connected to and spaced from the engagement surface for insertion into a complementary bore (12) provided at the joint end at a distance from the joint end surface (14). The elongate fixture forms an acute angle (&bgr;) with the engagement surface (3b).

Abstract: The invention relates to joint prosthesis elements, to a method of manufacturing prostheses, and to a kit for putting said prostheses into place. The prosthesis element which is put into place in a resection in the joint surface is defined by a contact surface C, a fixing surface F and, interconnecting said surfaces, a peripheral surface P which co-operates with a projecting rim R of the resection. An anchoring element A projects from the fixing face and penetrates into a corresponding anchoring hole D.

Abstract: A knee joint prosthesis, comprising at least one femoral component and at least one tibial component. The femoral component having a first portion adapted for fixable attachment to a distal end of a femur and a second portion formed with a bearing surface. The femoral component is sized so as to permit attachment to the femur of a patient without severing at least one the cruciate ligaments. The tibial component has a first surface that is adapted to cooperate with a patient's tibia, while a second surface of the tibial component is adapted to cooperate with the femoral component. The tibial component is sized so as to permit attachment to the patient's tibia without severing at least one of the cruciate ligaments.

Abstract: A medical prosthesis for use within the body which is formed of radiation treated ultra high molecular weight polyethylene having substantially no detectable free radicals, is described. Preferred prostheses exhibit reduced production of particles from the prosthesis during wear of the prosthesis, and are substantially oxidation resistant. Methods of manufacture of such devices and material used therein are also provided.

Abstract: A method for preparing a contact surface of an implantable bone, joint or similar prosthetic component subject to contact or motion includes the steps of mounting the prosthetic component on a turning or cutting machine and cutting the face of the prosthetic component with a diamond cutting tool using computerized control of tool position along a cross direction to machine cut a super finished surface. The diamond cutting tool has a precise contact point and is shaped with a waviness under about 0.5 micrometers effective to cut a surface profile free of visible tool marks. As cut, the variations of contour and the surface roughness are both under about 0.5 micrometers, and preferably under about 0.2 micrometers or less. Upon implantation, the super finished surface generates wear particles at an asymptotically low or residual level during wear-in which may enhance wear characteristics and reduce local reaction or systemic rejection effects.

Abstract: A control system is adapted for use In association with a therapeutic motion and splinting device. The therapeutic device has at least one component that is monitored. The system comprises the steps of defining the range of motion, defining the maximum reverse on load, monitoring the reverse on load and moving the device through its range of motion. A first and second maximum limit of range of motion in a first and second direction are respectively defined. A maximum reverse on load is defined and is monitored whereby the deformation of the at least one component is monitored and the load created is interpreted. The device is cycled between a first and second position defined by one of the first maximum limit and the maximum reverse on load and one of the second maximum limit and the maximum reverse on load respectively.

Abstract: A toe implant (10) for a first metatarsal phalangeal joint (22) between a metatarsal (24) and a proximal phalanx (26) of a great toe (12) includes a proximal stem (16), a distal stem (18) and a hinge (20) and a strength rib (92). Importantly, the toe implant (10) is designed to accommodate an axis of motion in a unique location (82) and the distal stem (18) is naturally positioned lower than the proximal stem (16). Further, the toe implant (10) provides a relatively good available range of motion. With this design, the toe implant (10) maintains the proximal phalanx (26) in the correct anatomic position relative to the metatarsal (24) during bending and flexing. Additionally, the toe implant (10) allows the toe (12) to move in a fashion that simulates the natural motion of the first metatarsal phalangeal joint (22). As a result thereof, the toe implant (10) that does not significantly increase the stress at the joint (22) or alter the normal flexing of the toe (12).

Abstract: A cartilage plug, which is made from a biocompatible, artificial material, that is used to fill a void in natural cartilage that has been resected due to traumatic injury or chronic disease. Alternatively, the plug may be relied upon to anchor a flowable polymer to subchondral bone. The plug is prefabricatable in any size, shape, and contour and may be utilized either singly or in a plurality to fill any size void for any application. The plug may be formed of a laminated structure to match the physiological requirements of the repair site. A plurality of anchoring elements may share a single upper layer.

Abstract: A spacing device for supporting a joint adjacent to diseased bone or missing bone tissue, including a support piece and a semi-resilient pad. The pad is shaped to cradle and support the healthy bone joint. The reverse side of the pad is fixedly connected to one end of the support piece. The other end of the support piece is shaped to straddle healthy tissue adjacent the damaged area, such as the ilium when supporting a hip joint and is to be fixedly connected to the adjacent healthy tissue, using a suitable mechanism, such as biocompatible Steinman pins. Diseased, damaged, or necrotic tissue can be removed without requiring removal of the natural bone joint. Because the undamaged bone joint is not replaced, the problems commonly experienced during and following bone joint replacement are avoided. In particular, blood loss during surgery, surgical cost, surgical time, and rehabilitation of the patient after surgery is reduced.