Dynamic motion spinal stabilization system

A dynamic stabilization device for attachment to vertebral bodies comprising:

• a first member having first and second ends, wherein said first end is rotatably coupled to a first polyaxial head about only a first axis that extends through said first end and intersects a center point, wherein said center point is within a preselected A-P mark range of said vertebral bodies when said dynamic stabilization system is attached to said vertebral bodies and wherein said first sol axial head is configured to be head fixedly coupled to a bone anchor;
• a second member having a third end and a fourth end, said third end rotatably coupled to a second polyaxial head about only a second axis that extends through said third end and intersects said center point, and said fourth end moveably coupled to said second end, wherein said second polyaxial head is configured to be fixedly coupled to a bone anchor;
• and
• a third member movably coupling said second and fourth ends, wherein after said dynamic stabilization system is attached to said vertebral bodies said first, second, and third members are configured to maintain the intersection of said first and second axes with said center point as said center point moves along a curved three dimensional surface during movement of said first member relative to said second member.

A method comprising:

• identifying a center of rotation between first and second vertebrae;
• coupling a first member of a dynamic stabilization device to a first polyaxial head;
• coupling a second member of said dynamic stabilization device to a second polyaxial head;
• orienting an axis of said first polyaxial head with said center of rotation;
• orienting an axis of said second polyaxial head with said center of rotation;
• and
• securing said first and second members relative to said first and second polyaxial heads, respectively, to maintain the orientation of said first and second axes with said center of rotation during movement of said first member relative to said second member.

A dynamic stabilization system for attachment to vertebral bodies, said dynamic stabilization system comprising:

• a left construct comprising a left upper polyaxial screw head attaching to an upper vertebra, a left lower polyaxial screw head attaching to a lower vertebra, a left first member connected to said left upper polyaxial screw head, and a left second member connected to said left lower polyaxial screw head, said left first member and said left second member being hingedly connected to each other;
• and
• a right construct comprising a right upper polyaxial screw head attaching to said upper vertebra, a right lower polyaxial screw head attaching to said lower vertebra, a right first member connected to said right upper polyaxial screw head, and a right second member connected to said right lower polyaxial screw head, said right first member and said right second member being hingedly connected to each other;
• wherein a first longitudinal centroidal axis passing through a center of said left upper polyaxial head is aligned with a center of rotation, a second longitudinal centroidal axis passing through a center of said left lower polyaxial head is aligned with said center of rotation, a third longitudinal centroidal axis passing through a center of said right upper polyaxial head is aligned with said center of rotation, and a fourth longitudinal centroidal axis passing through a center of said right lower polyaxial head is aligned with said center of rotation;
• wherein said left first member and said left second member have a first concave curvature with respect to said vertebral bodies when installed on said vertebral bodies, said first concave curvature defined to maintain said intersection of said first longitudinal centroidal axis and said second longitudinal centroidal axis with said center of rotation;
• and
• wherein said right first member and said right second member have a second concave curvature with respect to said vertebral bodies when installed on said vertebral bodies, said second concave curvature defined to maintain said intersection of said third longitudinal centroidal axis and said fourth longitudinal centroidal axis with said center of rotation.