Abstract: A constrained prosthetic knee having a modular hinge post and a rotating bearing. A cannulated hinge post is rotatably connected to the femoral component of the knee prosthesis so that a hinge post extension may be anteriorly positioned through the hinge post and into the tibial component of the knee prosthesis, after positioning of the femoral component in the femur and the tibial component in the tibia. The hinge post is preassembled to the femoral component so that such assembly is not required during the implantation procedure. A meniscal component forming the rotating bearing of the knee prosthesis is packaged together with the hinge post extension so that the appropriate hinge post extension is readily available. The meniscal component includes a mechanism for preventing lift off of the meniscal component from the tibial component, while allowing rotation of the meniscal component relative to the tibial component.

Abstract: A replacement knee implant has a femoral implant and a tibial implant, each of which are inset in a bone surface. The tibial implant is generally elongated with one end rounded and an opposite end conforming to the shape of the tibia, and is made of a metal alloy or a ceramic. The upper surface is dished while the lower surface is planar and can be parallel or sloped relative to the upper surface. The femoral implant for implementation in a femoral condyle is rounded such that, when implemented, the femoral implant is flush at the anterior and posterior sides and protruding away from the femur between the anterior and posterior ends. The femoral implant can have an elongated keel for extending into the femur, and can be made from a highly cross-linked polyethylene.

Abstract: An instrumented linkage system (100) to facilitate accuracy and efficiency of a surgical procedure is disclosed. The linkage system may be directly attached to a bone and used to register the bone to a computer. The linkage system may also be used to verify the accuracy and alignment of planned resections relative to the bone.

Abstract: The modular stem component may include a shaft portion, a head, and a sleeve. The shaft portion is configured for receipt within the intramedullary canal of a bone and the head is configured to receive another component of a modular prosthetic system, such as a femoral neck, thereon. In one exemplary embodiment, the head extends radially around at least a portion of the stem and includes a rib defining a flange extending therefrom. The sleeve, which is formed as an independent part of the modular stem component and is made at least partially of a highly porous biomaterial, includes opposing ends and has a bore extending therethrough. The bore is configured to facilitate sliding receipt of the sleeve on the head.

Abstract: A constrained prosthetic knee having a modular hinge post and a rotating bearing. A cannulated hinge post is rotatably connected to the femoral component of the knee prosthesis so that a hinge post extension may be anteriorly positioned through the hinge post and into the tibial component of the knee prosthesis, after positioning of the femoral component in the femur and the tibial component in the tibia. The hinge post is preassembled to the femoral component so that such assembly is not required during the implantation procedure. A meniscal component forming the rotating bearing of the knee prosthesis is packaged together with the hinge post extension so that the appropriate hinge post extension is readily available. The meniscal component includes a mechanism for preventing lift off of the meniscal component from the tibial component, while allowing rotation of the meniscal component relative to the tibial component.

Abstract: A knee prosthesis includes a femoral component in which the condyles have a continuous contact surface for the tibial bearing surface and in which the sagittal radius is constant from posterior to a point more anterior than the distalmost point, The tibial bearing surface is shaped to have a curvature which corresponds closely with that of the femoral condylar surfaces. The tibial component includes a plastics meniscus component supported on a metal platform for sliding movement in the anterior-posterior direction and the mating surface between the meniscus and platform has a sagittal curvature which is larger than the sagittal radius of the femoral condyles.

Abstract: A knee prosthesis includes a femoral component in which the condyles have a continuous contact surface for the tibial bearing surface and in which the sagittal radius is constant from posterior to a point more anterior than the distalmost point. The tibial bearing surface is shaped to have a curvature which corresponds closely with that of the femoral condylar surfaces. The tibial component includes a plastics meniscus component supported on a metal platform for sliding movement in the anterior-posterior direction and the mating surface between the meniscus and platform has a sagittal curvature which is larger than the sagittal radius of the femoral condyles.

Abstract: A modulator apparatus for use in the preparation of bone surfaces and the implantation of a modular total knee prosthesis in a patient, which apparatus comprises cutting guides, templates, alignment devices, a distractor and clamping instruments which provide modularity and facilitate bone resection and prosthesis implantation.

Abstract: A modulator apparatus for use in the preparation of bone surfaces and the implantation of a modular total knee prosthesis in a patient, which apparatus comprises cutting guides, templates, alignment devices, a distractor and clamping instruments which provide modularity and facilitate bone resection and prosthesis implantation.

Abstract: A modular apparatus for use in the preparation of bone surfaces and the implantation of a modular total knee prosthesis in a patient, which apparatus comprises cutting guides, templates, alignment devices, a distractor and clamping instruments which provide modularity and facilitate bone resection and prosthesis implantation.

Abstract: A customized human joint prosthesis replicating the primary contours and dimensions of a patient's bone is designed and manufactured utilizing an average anatomical bone shape. The average anatomical bone shape is generated by digitizing and storing in a computer memory the average three dimensional shape of a significant number of actual bone portions corresponding to the bone portion to be replaced by the prosthesis. Thereafter, the scale of the patient's bone is determined by measuring the outside dimensions of the patient's bone in at least one plane parallel to the longitudinal axis of that bone. The average anatomical shape then is adjusted to form a first synthesized shape which conforms to that scale. Subsequently, the actual shape of the bone of the patient is measured along a plurality of longitudinally spaced lines in at least one plane normal to the longitudinal axis of the patient's bone.

Abstract: A method of designing a prosthesis having convex male and concave female mating portions is provided for a human joint comprising a condylar male portion the surface of which is generated by the piecewise analysis of an anatomical condyle, which can be an average condyle or a selected condyle, or a distortion of an average condyle to fit the observed general dimensions of a specific patient, and the female portion having at least flexion and laxity surfaces, the flexion surfaces of which are generated by plotting the path of articulation of substantial points of contact between said male portion and a corresponding anatomical female component for said joint through the full normal extension-flexion range plus normal rotation and posterior-anterior displacement for that joint, and the laxity surfaces of said female member comprising raised guide-bearing surfaces for resisting dislocation of the condylar portion, the height and angle, and therefore, the resistance to dislocation, of which guide bearing surfaces

Abstract: A prosthesis and a surgical procedure (process) therefore are provided having a relatively thin plate fitted to a resected portion of the tibial plateau with the plate fitting uniformly around a major portion of the calcareous bone of the cortical wall. A pin on the under side of the plate aligned substantially with the axis of the intramedullary canal of the tibia fixes the plate against transverse relative motion between the plate and plateau, and blades or keels also on the under side of the plate are aligned maximum density (strength) of the cancellous bone of the plateau and fix the plate against rotation relative to the plateau. The surgical procedure of the invention employs a template to assure approximate positioning, and exact interrelationship between the plate and the fixing means.

Abstract: A motion guiding load bearing external linkage for a knee is provided by plates fixed to the medial and lateral sides of the tibia and femur by transcutaneous pins or incorporated in a knee brace fitting above and below the knee joint. The tibial plates have a planar load bearing surface while the femoral plates have a circular load bearing surface. Linkages are provided for guiding the center of rotation of the femoral load bearing surfaces in the direction of the tibial load bearing surfaces as a function of the degree of knee flexure. This linkage comprises an extension of the tibial plate having a slot which engages a pin fixed to the femoral plate at a point off-set from the center of rotation. This linkage positively guides the motion of the center of rotation along a single path which is predetermined by the radial and annular position of the pin.

Abstract: A bone cement applicator for applying a predetermined amount of cement to uniformly penetrate a bone comprising a plunger terminating in an integral flat substantially rigid applicator plate, preferably metallic, and being slidably mounted in a tubular sleeve integral with an open-ended reservoir around the applicator plate, the periphery of said reservoir having a configuration conforming to the bone surface area to which the cement is applied and a method of applying bone cement using said applicator. The applicator is particularly adapted for the application of bone cement in total knee replacement.

Abstract: An intramedullary multiple pin device for fixing fractures in the middle portion (diaphysis) of long bones. The multiple pins are resilient and held in a desired special arrangement by a flexible plastic core element.

Abstract: A novel joint prosthesis, particularly suitable as a metacarpophalangeal joint prosthesis, is disclosed comprising first and second intramedullary plugs adapted to be secured to the walls of the intramedullary canals of the two bones forming the joint, and first and second components each comprising a bearing portion and a stem slidably received in a longitudinal bore provided in each of said intramedullary plugs. Transmission of stresses to the bone-prosthesis fixation interfaces is substantially reduced as a result of the freedom of motion of the stems within these longitudinal bores. In a preferred embodiment, axial rotation of one, but only one, of said stems with respect to the intramedullary plug receiving it is prevented. Use of preferred configurations for the bearing portions of the two components provides an accurate reproduction of the movement and degrees of freedom of the natural metacarpophalangeal joint.

Abstract: A knee joint prosthesis comprises a femoral component having laterally spaced-apart condylar portions shaped to match generally the shapes of the condylar surfaces of the femur and a tibial component having a plate-like platform portion which includes laterally spaced-apart concavities in the external surface, each of which receives and supports one of the condylar portions of the femoral component in all positions of the leg. The femoral component has a box-like intercondylar portion interconnecting the condylar portions and defining an intercondylar recess which receives a post that extends upwardly from the tibial component. At and near full extension of the leg, any tendency for posterial dislocation of the femur results in engagement between the anterior surfaces of the post and recess to prevent posterial dislocation of the femoral component relative to the tibial component.

Abstract: A novel knee prosthesis is disclosed comprising a femoral component and a tibial component adapted respectively to be secured to the adjacent ends of the femur and tibia, with each component comprising a spaced pair of bearing portions for articulation of the knee in the sagittal plane. A first guiding surface carried by the femoral component cooperates with a second guiding surface carried by the tibial component to induce posterior movement of the contact area of the femoral bearing portions upon the tibial bearing portions with increasing flexion of the knee. The two guiding surfaces are preferably located in the intercondylar region. The prosthesis may also be adapted for use in other joints, e.g. the elbow.