Abstract: The prosthesis comprises a femoral component (2) having at least one substantially spheroidal condylar bearing surface (10,11), a tibial component (6) including a tibial platform (20), and a plastics meniscal component (7) located between the condylar bearing surface (10,11) an the tibial component (6) and being slidable on the platform (20). The meniscal component (7) is retained on a guide (23) upstanding from the platform (20). The guide (23) includes a post (24) and a cap (25) which is a snap-fit in a recess (30) in the meniscal component (7). The guide (23) is slidable in a track (32) within the meniscal component (7) so that movement of the meniscal component (7) in the anterior/posterior direction (A-P) is limited by impingement of the meniscal component (7) on the post (24) and/or on a rail member (21) projecting from the surface of the tibial platform (20).

Abstract: The invention provides means for evaluating the fit of a knee replacement prosthesis on a resected tibial surface. A provisional instrument for this purpose includes a positioning tray having a peripheral profile corresponding to that of the tibial platform of the prosthesis, the tray having an upper surface and an under surface which is substantially flat and free from projections and the tray having a plurality of holes for receiving pins for temporarily attaching the positioning tray in a desired position on the resected tibial surface. Also disclosed is a jig for guiding, drilling and broaching operations, the jig having an aperture which is shaped to guide the broach.

Abstract: A condylar replacement knee prosthesis has a tibial platform adapted for attachment to a resected tibia, a femoral component adapted for attachment to a resected femur and a plastics meniscal component interposed between the femoral and tibial components. The upper surface of the meniscal component is shaped to correspond with bearing surfaces of the femoral component. The meniscal component is guided for sliding movement in an anterior-posterior direction on the tibial component and for limited rotational movement, the rotational movement being centred about an axis which is displaced medially from the anterior-posterior centre line of the tibial component.

Abstract: A femoral prosthesis is disclosed comprising a bicondylar femoral component (41), a tibial component (72) and at least one meniscal component (42) interposed between the femoral and tibial components, the femoral component including a pair of condylar surfaces (46) separated by a patella bearing surface (44) which in use provides a normal anatomical patella lever arm, the condylar surfaces being shaped for substantial conformity with corresponding tibial bearing surfaces (47) of the meniscal component or components over the entire range of normal flexion.