Knee joint prosthesis

Claim 2

A prosthetic knee joint device comprising: a femoral bearing member of generally U-shaped form having a first side wall, a base, and a second side wall, defining relative to said U-shape a major outer surface and a major inner surface, said outer surface having a convex first profile extending in a circumferential direction around said U-shape and including a convexly curved first profile part extending over said first wall and partway across said base, a rectilinear second profile part continuing across said base from said first profile part, and a convexly curved third profile part continuing across said second wall from said second profile part; and a tibial bearing member in the form of a platform having a major upper surface and a major lower surface, said upper surface being dished in one direction thereacross to provide a concave second profile generally complementary to said convex first profile, said concave second profile including a concavely curved central profile part of the same order of curvature as and in mutual articulatory bearing engagement with said first profile part, and a rectilinear outer profile part continuing from said central profile part in similar angular relationship therewith to that between said femoral first and second profile parts, said femoral second and tibial outer profile parts engaging to limit said articulatory engagement.

Claim 3

A device according to claim 1 wherein said first and central profile parts are both curved in circular arcuate manner with the same radius of curvature.

Claim 4

A device according to claim 2 wherein said third profile parT is curved in circular arcuate manner with a lesser radius of curvature than said first profile part.

Claim 5

A device according to claim 1 wherein said concave second profile comprises a further rectilinear outer part continuing from said central profile part in similar manner to and symmetrical relationship with the first-mentioned rectilinear outer profile part.

Claim 6

A device according to claim 1 wherein said outer surface is formed with a first groove extending across said second wall in said circumferential direction.

Claim 7

A device according to claim 1 wherein said first wall extends further from said base in said circumferential direction than said second wall.

Claim 8

A device according to claim 1 wherein said first side wall is of greater extent in a direction orthogonal to said circumferential direction than said second wall, and said base is symmetrically convergent between said differing first and second side wall extents.

Claim 9

A device according to claim 1 wherein said outer surface is formed with a second groove extending across said first wall and partway across said base in said circumferential direction, and said platform member is provided with a peg upstanding from said upper surface and slidably engaged in said second groove.

Claim 10

A device according to claim 1 wherein said femoral bearing member is slotted therethrough in said circumferential direction wholly across said first side wall and partway across said base, and said platform member is correspondingly slotted partway thereacross from its periphery.

Claim 11

A device according to claim 1 wherein said femoral bearing member is adapted for fixation to the femur by the provision of an intramedullary stem upstanding from said inner surface across said base to an extent intermediate that of said first and second side walls.

Claim 12

A device according to claim 1 wherein said femoral bearing member is adapted for fixation to the femur by the provision of inturned portions around at least part of the periphery thereof communicating said inner and outer surfaces.

Claim 13

A device according to claim 1 wherein said tibial bearing member is adapted for fixation to the tibia by the provision of a subsidiary platform extending from said lower surface, which subsidiary platform has undercut edges.

Claim 14

A device according to claim 1 wherein said femoral bearing member is symmetrical about a first plane wholly including said U-shaping, and said tibial bearing component is symmetrical about both said first plane and a second plane which is mutually orthogonal with said first plane and said upper and lower surfaces.

Claim 15

A prosthetic knee joint device comprising: a femoral bearing member of generally U-shaped form having a first side wall, a base, and a second side wall, defining relative to said U-shape a major outer surface and a major inner surface, said outer surface having a convex first profile extending in a circumferential direction around said U-shape and including a convexly curved first profile part extending over said first wall and partway across said base, a relatively flat second profile part continuing across said base from said first profile part, and a convexly curved third profile part continuing across said second wall from said second profile part; and a tibial bearing member in the form of a platform having a major upper surface and a major lower surface, said upper surface being dished in one direction thereacross to provide a concave second profile generally complementary to said convex first profile, said concave second profile including a concavely curved central profile part of the same order of curvature as and in mutual articulatory bearing engagement with said first profile part, and a relatively flat outer profile part continuing from said central profile part in similar angular relationship therewith to that between said femoral first and second profile parts, said femoral second and tibial outer profile parts engaging to limit said articulatory engagement.

Claim 16

A prosthetic knee joint device comprising: a femoral bearing member of generally U-shaped form having a first side wall, a base, and a second side wall, defining relative to said U-shape a major outer surface and a major inner surface, said outer surface having a convex first profile extending in a circumferential direction around said U-shape and including a convexly curved first profile part extending over said first wall and partway across said base, a relatively flat second profile part continuing across said base from said first profile part, and a convexly curved third profile part continuing across said second wall from said second profile part; and a tibial bearing member in the form of a platform having a major upper surface and a major lower surface, said upper surface being dished in one direction thereacross to provide a concave second profile generally complementary to said convex first profile, said concave second profile including a concavely curved central profile part of the same order of curvature as and in mutual articulatory bearing engagement with said first profile part, and a relatively flat outer profile part continuing from said central profile part in similar angular relationship therewith to that between said femoral first and second profile parts, said femoral second and tibial outer profile parts engaging to limit said articulatory engagement.

Claim 17

A device according to claim 14 wherein said concave second profile comprises a further relatively flat outer part continuing from said central profile part in similar manner to and symmetrical relationship with the first-mentioned relatively flat outer profile part.

Claim 18

A device according to claim 14 wherein said first and central profile parts are both curved in circular arcuate manner with the same radius of curvature.

Claim 19

A device according to claim 14 wherein said outer surface is formed with a first groove extending across said second wall in said circumferential direction.

Claim 20

A device according to claim 14 wherein said first wall extends further from said base in said circumferential direction than said second wall.

Claim 21

A device according to claim 14 wherein said first side wall is of greater extent in a direction orthogonal to said circumferential direction than said second wall, and said base is symmetrically convergent between said differing first and second side wall extents.

Claim 22

A device according to claim 14 wherein said outer surface is formed with a second groove extending across said first wall and partway across said base in said circumferential direction, and said platform member is provided with a peg upstanding from said upper surface and slidably engaged in said second groove.

Claim 23

A device according to claim 14 wherein said femoral bearing member is slotted therethrough in said circumferential direction wholly across said first side wall and partway across said base, and said platform member is correspondingly slotted partway thereacross from its periphery.

Claim 24

A device according to claim 14 wherein said femoral bearing member is adapted for fixation to the femur by the provision of an intramedullary stem upstanding from said inner surface across said base to an extent intermediate that of said first and second side walls.

Claim 25

A device according to claim 14 wherein said femoral bearing member is adapted for fixation to the femur by the provision of inturned portions around at least part of the periphery thereof communicating said inner and outer surfaces.

Claim 26

A device according to claim 14 wherein said tibial bearing member is adapted for fixation to the tibia by the provision of a subsidiary platform extending from said lower surface, which subsidiary platform has undercut edges.

Claim 27

A device according to claim 14 wherein said femoral bearing member is symmetrical about a first plane wholly including said U-shaping, and said tibial bearing component is symmetrical about both said first plane and a second plane which is mutually orthogonal with said first plane and said upper and lower surfaces.