Abstract: A process for improving the start up and steady rate friction of soft/compliant polyurethane bearings uses a pre-treatment with Ringers solution. The process includes treating the polyurethane in a heated bath of the solution for 96 hours at a temperature of between 30° C. and 37° C.

Abstract: A profile gauge for use with an acetabular cup loading tube provided with a skirt or flange characterized by adjustable means for measuring and indicating the diametric profile of the mouth of the rim area adjacent thereto of an acetabular socket into which an acetabular cup is to be implanted and includes means for removably locating said adjustable means on a loading tube to indicate on the skirt thereof the measured diameter profile.

Abstract: A Process is described in which the polymer is passed over a former under hydro-static pressure, which may involve passing the material over a die or series of dies for the purpose of imposing multi-axial expansion to the workpiece. Some of the advantages are increased stiffness and reduction in creep. Improved wear is also found.

Abstract: An apparatus for impacting bone chips in a bone canal. The impactor has an impaction head of predetermined dimensions and a stem extending therefrom. There is a visual indicator provided with means for secure location on said stem to visually indicate the distance of insertion of the impaction head within a bone canal.

Abstract: A metal backing for inclusion in the manufacture of a prosthetic component having a plastic on an upper surface and has a bottom surface portion with elements for attachment to a bone. The backing has an upper surface portion at least part of which is formed by a grill element having exposed front and rear faces and which is intended to be embedded within the plastic bearing member during construction. The plastic bearing material of the bearing element can be molded so that all the faces thereof exposed to the grill are covered and the grill is embedded within the plastic material of the bearing element. The grill is located on a metal support and is provided with spacers on its front face to space the front face away from the support. The grill is cast integrally into the metal support during manufacture. The casting process includes casting a grill on both outer surfaces of the metal backing with the grill element including cross-members spaced from backing surfaces.

Abstract: A tibial element for a replacement knee prosthesis has a tibial tray, fastening connector for securing an attachment element to the lower part of the tray, and also provided with independently operable securing boss at its upper end which engage a cooperating construction on a bearing component to secure the bearing component to the upper part thereof. The fastening connector allows for a stronger construction than the previous arrangements and it also allows for a convenient modular construction which will allow a standard modular tray to be employed with various types of bearing construction, for example, a fixed component or a sliding component.

Abstract: A prosthetic bearing element comprises a backing which supports a bearing liner having a bearing surface. The backing is made from a "hard" polymeric material having a minimum hardness value of 55 N/mm.sup.2 and the bearing liner is made from a "soft" elastomeric polyurethane material having a hardness value of 3.0 to 9.0 N/mm.sup.2.

Abstract: A tibial element is provided for a replacement knee prosthesis which comprises a tibial tray provided with a bearing component having medial and lateral compartments. Control means acting between the tray and the bearing component are included which provide free posterior and anterior movement of the lateral compartment which is greater than any allowed free posterior and anterior movement of the medial compartment in relation to the tray. Thus, there is no relative free posterior movement and anterior movement of the medial compartment or some may be allowed.

Abstract: A method of implanting an acetabular cup which includes the step of preparing an acetabular socket to receive a cup, placing cement in the acetabular socket before or after locating a tube in line with the acetabular socket and inserting the acetabular cup through the tube and into the socket.

Abstract: An apparatus for performing prosthesis surgery has a phantom implant component. Elements are provided for holding said phantom component accurately and stationary relative to a cavity in a bone. The phantom component has a tapered insert portion, the dimensions of which are identical to the insert portion of an implant component which is to be fitted. A method of performing prosthesis surgery is included which uses the apparatus set forth above which includes preparing an opening in a bone with cement, inserting the insert portion of the phantom component, allowing the cement to at least partially set, removing the phantom component, inspecting the cement and then inserting the implant component with the identical insert portion dimensions.

Abstract: A targeting device for making holes in cortical bone for bone nails has a right angle drill which interconnects to a telescopic guide member. The guide member attaches to the drill at the side thereof opposite the chuck. The free end of the telescopic guide attaches to an X-ray machine and maintains the drill in position during the drilling operation. A manual targeting device is used to locate bores in the bone nail and to spot drill the bone. The aligned telescopic guide is then used to complete the drilling operation.

Abstract: A joint replacement surgical apparatus including a main body part, first and second tissue engaging plates mounted on the main body part, the first tissue engaging plate being displaceable towards and away from the second tissue engaging plate. At least one of the first and second tissue engaging plates is adapted to be oriented by the tissue engaged thereby. The first and second tissue engaging plates define respectively first and second substantially planer tissue engaging surfaces, each of the tissue engaging surfaces being arranged such that the surfaces face away from each other.

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: An intramedullary intertrochanteric fracture fixation appliance has an intramedullary rod having an angulated opening to receive a femoral neck screw. The femoral neck screw has a threaded portion at its proximal end of predetermined diameter. A locking element is provided which acts between the neck screw and the wall of the angulated opening to prevent relative rotation between the screw and the rod.

Abstract: A prosthetic tibial component has a tibial tray having an underside for engaging a prepared tibial plateau. The tibial component has a stem having a tapered connection at one end. The stem has a non-symmetrically shaped bone engagement element extending therefrom. The tray includes a tapered connection element for mating with the tapered connection element on the stem. The tray includes an alignment element for locating and engaging the bone engagement element on the stem to locate the stem at a predetermined position relative to the tibial plateau.

Abstract: A total hip replacement femoral component has an outer surface shaped to conform to an acetabular socket and has an internal bore adapted to receive a femoral head. The head has been shaped and dimensioned to provide a spigot to enter the bore and be locked in place by a cement mantle between the bone and the walls of the bore. The head allows the hip component to move further over said spigot and re-lock should the cement creep or thereby any movement in the bone after assembly. The internal bore is inwardly tapered. Thus the taper can be co-axial with the femoral neck, but there may be advantages in orientating the axis of the taper as close to vertical as possible when in position so that it is closer to the average force vector acting on the femoral head during human activity.

Abstract: A prosthetic intramedullary femoral prosthesis provided with a separate preformed sheath made from an acrylic material which is dimensioned to enclose the prosthesis stem from the distal tip to a location on the stem which will be adjacent the proximal cut end of the femur with which it will be used.

Abstract: An intramedullary intertrochanteric fracture fixation appliance comprising an intramedullary rod having an angulated opening to receive a femoral neck screw, said rod having a co-axial bore extending into said angulated opening, anti-rotation means located in said bore to selectively prevent rotation of said neck screw in the rod and the open end of said bore being provided with means to positively locate a removable fitting device on the proximal end of the rod and so that said anti-rotation means can be operated with the fitting device in position.

Abstract: An acetabular cup for use in a total hip prosthesis includes an implant/cement interface portion for location in a cement mantle. The cup has an enclosure element for allowing the cup to slide lengthwise to re-engage itself in the cement mantle to accommodate creep or movement thereof. Thus, should there be a tendency for the cup to become loose, the construction according to the invention is intended to relock the cup within the cement mantle. Thus, if the bone remodels, then the cement mantle will creep to re-adapt itself to the bone and the implant will re-engage in the cement mantle accommodating to the movement of the cement. If the bone cement is too highly stressed in places, it will creep in order to relieve this stress and the implant will re-settle.

Abstract: A centralizer for the stem of a prosthetic orthopedic implant adapted for implantation into a medullary canal has a hollow annular body portion. The annular body portion has an interior for receiving the stem of the implant. The body portion also includes at least three spring elements extending outwardly from the exterior surface of the body portion. Each spring element has a portion thereof extending generally tangentially with respect to the axial extent of the tapered stem and deformable circumferentially and inwardly towards the stem upon insertion into the medullary canal.