Patent ID: 9138329
Filing Date: 2015-09-22
Classification: A61B,A61F

Abstract:
1. A prosthesis for a vertebral column, comprising: an upper part for attachment to an upper vertebrae, said upper part having a convex lower surface portion with a first radius of curvature and a first curved length; a lower part for attachment to a lower vertebrae, said lower part having a convex upper surface portion with a second radius of curvature and a second curved length; and a middle part located between the upper and lower parts, said middle part having a concave upper surface portion and a concave lower surface portion, said concave upper surface portion having a third radius of curvature and a third curved length, and said concave lower surface portion having a fourth radius of curvature and a fourth curved length, said middle part also including a generally flat side wall portion extending between said concave upper surface portion and said concave lower surface portion to define a perimeter of said middle part; wherein said first curved length of said convex lower surface portion of said upper part is greater than said third curved length of said concave upper surface portion of said middle part, and wherein said second curved length of said convex upper surface portion of said lower part is greater than said fourth curved length of said concave lower surface portion of said middle part; wherein said convex upper surface portion of said lower part and said concave lower surface portion of said middle part are cylindrical from a first side to a second side and configured to allow both rotational and translational movement between said middle part and said lower part during use, and wherein said convex lower surface portion of said upper part and said concave upper surface portion of said middle part are completely spherical and configured to allow rotational but not translational movement between said middle part and said upper part during use; wherein said first radius of curvature of said upper part is equal to said third radius of curvature of said middle part, said second radius of curvature of said lower part is equal to said fourth radius of curvature of said middle part, and said third radius of curvature of said middle part is different from said fourth radius of curvature of said middle part such that, during use, said first radius of curvature, second radius of curvature, third radius of curvature, and fourth radius of curvature are configured to provide a stable equilibrium position wherein said middle part will self-center between said upper part and said lower part.