Artificial knee joint capable of preventing dislocation of thighbone coupling member

An artificial knee joint comprising:

• a thighbone coupling member;
• and
• a bearing member having a distal surface extending anteriorly and posteriorly, wherein
• the bearing member includes a post having a contact surface in contact with the thighbone coupling member;
• the thighbone coupling member includes a cam performing a cam motion relative to the post of the bearing member;
• and
• the post includes an upper surface at which the post performs a motion relative to the cam of the thighbone coupling member, an upper curved surface extending posteriorly from the upper surface, and a lower curved surface extending continuously from the upper curved surface, wherein the upper curved surface and the lower curved surface have respective centers of curvature that are disposed opposite an inflection point existing therebetween,
• the center of curvature of the lower curved surface is disposed posteriorly to the inflection point,
• the center of curvature of the upper curved surface is disposed anteriorly to the inflection point, and
• a radius of curvature of the lower curved surface is larger than that of the upper curved surface such that the upper curved surface protrudes posteriorly of the inflection point.

An artificial knee joint comprising:

• a thighbone coupling member comprising a cam having a cam surface, the cam surface being completely convex;
• and
• a bearing member that includes a post having a contact surface in contact with the cam surface on at least a posterior side of the post, the contact surface of the post comprising:
• an upper surface at which the post performs a motion relative to the cam of the thighbone coupling member;
• an upper curved surface extending posteriorly from the upper surface;
• a lower curved surface extending below and anteriorly from the upper curved surface;
• and
• an inflection point disposed between the upper curved surface and the lower curved surface,
• wherein:
• the lower curved surface has a center of curvature disposed posteriorly to the inflection point;
• and
• the upper curved surface has a center of curvature disposed anteriorly to the inflection point such that the upper curved surface protrudes posteriorly over the inflection point.