US 5,011,496 A · Prosthetic joint

Abstract

A prosthetic knee joint is provided having an extended position, an intermediate position, and a flexed position. The motion of the joint includes a minor segment from the extended position to the intermediate position, and a major segment from the intermediate position to the flexed position. The center of pressure between the femoral component and the tibial component moves rearward on the tibia during the minor segment. During the major segment, the joint flexes about an axis of rotation with the bearing surfaces on the femoral and tibial components being in congruent engagement. The distal surface of the femoral component includes two rails for engagement with a patellar prosthesis. The contour of the rails is either a straight line or a concave curve to provide line contact between the rails and the patellar prosthesis. In certain embodiments, the patellar prosthesis has a saddle-shaped surface so that the prosthesis and each of the rails can make contact over an area extending along the length of the rail.

Claims12

Dependent claims

A prosthetic joint for providing flexion motion between two bones comprising:

(a) a convex bearing component having a first bearing area and a contiguous second bearing area, the second bearing area being a surface of revolution about a first axis and having a radius of curvature which is less than the radius of curvature of the first bearing area;
and
(b) a concave bearing component having a third bearing area for engagement during flexion with the first bearing area and a contiguous fourth bearing area for engagement with the second bearing area, the fourth bearing area being a surface of revolution about a second axis and having a radius of curvature which is less than the radius of curvature of the third bearing area;
wherein:
the radius of curvature of the second bearing area is substantially the same as the radius of curvature of the fourth bearing area so that the second and fourth bearing areas may be in congruent engagement with one another;
and
the flexion axis of the joint is parallel to the first and second axes when the second and fourth bearing areas are in engagement.

4 more elements

Dependencies are inferred from the claim text.

Prosthetic joint

Life of this patent

Prosthetic joint

Life of this patent

Abstract

Claims12