Intervertebral disc prosthesis

An intervertebral disc prosthesis comprising:

• an upper plate,
• a lower plate having a substantially flat support surface,
• an intermediate element comprising a base having a rim and surmounted by a spherical cap,
• the upper plate having an indentation having exactly the same radius of curvature as the spherical cap and coming into contact with said cap so as to define a ball and socket joint between the upper plate and the intermediate element,
• the base of the intermediate element coming into contact with the support surface,
• the lower plate having a guide which is a closed recess in the lower plate, said guide comprising an anterior edge and a posterior edge facing each other, maintaining between them a substantially constant distance and holding between them the intermediate element,
• the rim of the base coming into contact with at least one of the anterior edge and posterior edge, wherein the rim is a circle in cross-section and is suited to allow the movement by rolling of the intermediate element along the anterior edge and posterior edge;
• wherein the edges of the guide have a non-circular conic type shape, so as to guide the intermediate element along a conic-type trajectory;
• wherein the edges of the guide have a parabolic shape.