Patent ID: 8317832

Claim:
A spinal implant, comprising: a spacer comprising a body having opposite upper and lower ends and structured for positioning in an interspinous gap between adjacent upper and lower spinous processes of a human spinal motion segment; the upper end structured to contact an inferior surface of the upper spinous process of the human spinal motion segment and the lower end structured to contact a superior surface of the lower spinous process of the spinal motion segment, wherein each of the upper and lower ends includes a concave portion sized and shaped to receive one of the respective upper and lower spinous processes and the concave portions are each disposed between a pair arms extending from the upper and lower surfaces, respectively, to engage with lateral surfaces of the spinous processes; the body comprising at least distinctive first and second sections forming an asymmetrical stiffness profile that varies between anterior and posterior sides of the spacer; wherein the first and second sections have flexibility characteristics that differ from one another, wherein one of the flexibility characteristics relates to a modulus of elasticity and wherein the second section has a smaller modulus of elasticity than the first section; wherein the anterior side defines the anterior extent of the spacer and the posterior side defines the posterior extent of the spacer; wherein the anterior side and the posterior side each extends from the upper end to the lower end; wherein the second section is positioned between the first section and the posterior side; wherein the spacer includes a first lateral exterior side and a second lateral exterior side, each lateral side extending from the upper end to the lower end; wherein the first section extends along the anterior side and the first and second lateral sides and the second section extends along the posterior side and the first and second lateral sides; wherein the spacer is configured such that, when the spacer is disposed both in the interspinous gap between the upper and lower spinous processes and external to a disc space defined by and between corresponding vertebral bodies so as to moveably support the upper and lower spinous processes, the spacer modifies a center of rotation of the vertebral bodies relative to each other in at least one of spinal extension and spinal flexion.