Knee prosthesis with a rotational plate

• US 6,299,646 B1
• Filed: 09/23/1998
• Issued: 10/09/2001
• Est. Priority Date: 09/23/1997
• Status: Expired due to Term

• Current Assignee: Corin Limited (Corin Medical Ltd. /Management/)
• Original Assignee: Tornier Incorporated
• Inventors: Deschamps, Gérard, Neyret, Philippe, Chambat, Pierre, Judet, Thierry
• Primary Examiner(s): Snow, Bruce
• Application Number:
  US09/158,791
• Time in Patent Office: 1,112 Days
• Field of Search: 623/20.33, 623/20.29, 623/20.15
• US Class Current: 623/20.33
• CPC Class Codes: A61F 2/3868 with sliding tibial bearing
• CPC Class Codes: A61F 2/389 Tibial components A61F2/3868 takes precedence
• CPC Class Codes: A61F 2002/30125 elliptical or oval
• CPC Class Codes: A61F 2002/30133 kidney-shaped or bean-shaped
• CPC Class Codes: A61F 2002/30153 rectangular
• CPC Class Codes: A61F 2002/30331 made by longitudinally pushing a protrusion into a complementarily-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2002/30365 with additional means for limiting said rotation
• CPC Class Codes: A61F 2002/30403 Longitudinally-oriented cooperating ribs and grooves on mating lateral surfaces of a mainly longitudinal connection
• CPC Class Codes: A61F 2002/305 Snap connection
• CPC Class Codes: A61F 2002/30535 Special structural features of bone or joint prostheses not otherwise provided for
• CPC Class Codes: A61F 2002/30688 Means for allowing passage or sliding of tendons or ligaments
• CPC Class Codes: A61F 2002/3082 Grooves
• CPC Class Codes: A61F 2002/30878 with non-sharp protrusions, for instance contacting the bone for anchoring, e.g. keels, pegs, pins, posts, shanks, stems, struts
• CPC Class Codes: A61F 2220/0025 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0033 made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2230/0008 elliptical or oval
• CPC Class Codes: A61F 2230/0015 Kidney-shaped, e.g. bean-shaped
• CPC Class Codes: A61F 2230/0019 rectangular
• CPC Class Codes: A61F 2250/0058 Additional features; Implant or prostheses properties not otherwise provided for
• CPC Class Codes: A61F 2310/00011 Metals or alloys

Abstract

Knee prosthesis comprising a metal base secured to an anchoring rod for fixing it into a tibia of a patient. A plastic tibia plate is freely slidable over the base. The metal base and the tibia plate are equipped with a guide mechanism defining a center of rotation offset from that of a tibia bone axis, so as to allow the plate to slide in rotation over the base. The guide mechanism is positioned a given distance from the center of rotation. The metal base comprises an upstand in the shape of an arc of a circle having a central part secured to lateral edges which are shorter than the central part. The tibia plate comprises, on a lower face thereof, a housing in the shape of an arc of a circle.

Claims

1. Knee prosthesis comprising:

a metal base secured to an anchoring rod for fixing it into a tibia of a patient;

a plastic tibia plate freely slidable over said base;

the metal base and the tibia plate being equipped with a guide mechanism defining a center of rotation offset from that of a tibia bone axis, so as to allow the plate to slide in rotation over said base;

said guide mechanism being positioned a given distance from the center of rotation;

said metal base comprising an upstand in the shape of an arc of a circle having a central part secured to lateral edges which are shorter than said central part;

said tibia plate comprising, on a lower face thereof, a housing in the shape of an arc of a circle.

2. Knee prosthesis according to claim 1, wherein said upstand is secured to the metal base, said housing having the same radius of curvature as the tibia plate to allow the latter to slide in rotation about a center of rotation of said upstand.

3. Knee prosthesis according to claim 2, wherein the upstand has a center of rotation which is borne by a tibia bone vertical axis, while said upstand is a given distance from its center of rotation.

4. Knee prosthesis according to claim 2, wherein the upstand has a center of rotation which is offset from a tibia bone vertical axis, while said upstand is a given distance from its center of rotation.

5. Knee prosthesis according to claim 1, wherein the metal base comprises said upstand, said upstand being of a first size, said upstand engaging with a housing of the tibia plate, said housing being of a second size, to permit said tibia plate to slide in rotation over the metal base only within the limit set by the difference in size between the said upstand and said housing.

6. Knee prosthesis according to claim 1, wherein the guide mechanism has a height and is positioned anteriorly on the metal base so as to permit the tibia plate to be mounted on said base via a strictly anterior approach, said plate requiring upward clearances only to the extent of the height of said guide mechanism.