Patent ID: 6997954
Filing Date: 2006-02-14
Classification: A61B,A61F,Y10S

Abstract:
1. A method for replacing at least a portion of an intervertebral disc in a spinal column, comprising: removing the portion of the intervertebral disc from the spinal column; and inserting an apparatus for replacing the portion of the intervertebral disc into an intervertebral disc space defined substantially between adjacent vertebral bones of the spinal column, and positioning the apparatus between the vertebral bones, the apparatus comprising a first member having a first vertebral contact surface for engagement with an endplate of a first of the vertebral bones in the spinal column and a first articulating surface, the entirety of the first articulating surface being a single saddle surface that is defined by a concave arc having a substantially constant radius of curvature A about a first axis perpendicular to an anterior-posterior plane of the spinal column, and a convex arc having a substantially constant radius of curvature B about a first axis perpendicular to a lateral plane of the spinal column; the apparatus comprising a second member having a second vertebral contact surface for engagement with an endplate of a second of the vertebral bones in the spinal column and a second articulating surface, the entirety of the second articulating surface being a single saddle surface that is defined by a convex arc having a substantially constant radius of curvature C about a second axis perpendicular to the anterior-posterior plane of the spinal column, and a concave arc having a substantially constant radius of curvature D about a second axis perpendicular to the lateral plane of the spinal column, said constant radius of curvature A being greater than said constant radius of curvature C and said constant radius of curvature B being less than said constant radius of curvature D; and the first and second members are operable to articulate with respect to one another to permit flexion and extension in an anterior-posterior plane of the spinal column, and to permit lateral bending in a lateral plane of the spinal column, respectively; wherein the apparatus is operable to permit the adjacent vertebral bones to articulate relative to one another about at least one of: (i) a first center of rotation for at least one of flexion and extension that is located below the articulating surfaces, and (ii) a second center of rotation for lateral bending that is located above the articulating surfaces.