Patent ID: 7578847

Claim:
A posterior intervertebral stabilizer, comprising: a first stabilizing element having: (i) a first surface operable to engage an endplate of a first vertebral bone of a spine, and (ii) a second surface spaced apart from the first surface and operable to engage an endplate of an adjacent second vertebral bone of the spine; a second stabilizing element having: (i) a first surface operable to engage an endplate of the first vertebral bone of the spine, and (ii) a second surface spaced apart from the first surface and operable to engage an endplate of the adjacent second vertebral bone of the spine; and spring elements, each including a substantially solid exterior wall forming a hollow passage between the first and second surfaces of the respective stabilizing element, the solid exterior wall including at least one helical slit therethrough forming a plurality of annular circumferential, overlapping helical coils, the respective spring elements being disposed between the respective first and second surfaces of the first and second stabilizing elements, each operable to provide a reactive force in response to compression loads from the first and second vertebral bones, wherein at least some diameters of respective turns of the respective helical coils differ such that those of the turns having larger diameters are disposed towards the first and second surfaces and those of the turns having smaller diameters are centrally located between the turns having larger diameters, and diameters of the hollow passage between the first and second surfaces vary such that larger diameters are disposed towards the first and second surfaces and smaller diameters are centrally located.