Artificial knee joint
An artificial knee joint, which makes a drag (a contact stress) acting on a sliding surface upon bending small so as to evade an extraordinary abrasion and damage of a sliding surface of a tibia component and which prevents an bending angle from being decreased by preventing lifting of a femoral component in a rotational movement. The artificial knee joint comprises a femoral component to be secured to a distal portion of a femur and a tibia component to be secured to a proximal portion of a tibia, comprising an inner sliding surface and an outer sliding surface receiving a load of the femoral component at the tibia component. In the inner sliding surface, both of a front side and a rear side are formed in a sectional shape of circular arc in the front-to-back direction thereof, while in the outer sliding surface, a front side is formed in a sectional shape of a circular arc and a rear side is formed in a linear sectional shape in the front-to-back direction thereof.
1. An artificial knee joint which comprises a femoral component to be secured to a distal portion of a femur and a tibia component to be secured to a proximal portion of a tibia, comprising a medial sliding surface and a lateral sliding surface for receiving a load of the femoral component at the tibia component, wherein the medial sliding surface is formed in a sectional shape of circular arc at the anterior and posterior side(s) in the anterior-to-posterior direction thereof, while the lateral sliding sectional shape of circular arc at the anterior side and in a sectional shape of linear at the posterior side(s) in the anterior-to-posterior direction thereof, wherein the anterior side of the medial sliding surface makes a circular arc having a curvature radius R 1 at a longitudinal section and the posterior side makes a circular arc having a curvature radius R 2 , wherein R 1 <R 2 .
2. An artificial knee joint according to claim 1 , wherein a middle portion of the medial sliding surface of the tibia component is formed in a linear sectional shape in the anterior-to-posterior direction.
3. An artificial knee joint according to claim 1 , wherein the lateral sliding surface of the tibia component is formed in a sectional shape of circular arc in a direction orthogonal to the anterior-to-posterior direction thereof, and a curvature radius of the circular arc in said orthogonal direction is gradually increased from the anterior side to the posterior side in the longitudinal direction thereof.
4. An artificial knee joint according to claim 1 , wherein the anterior side in the lateral sliding surface makes a circular arc having a curvature R 1 at a longitudinal section.