Intervertebral Prosthesis
An intervertebral prosthesis for insertion between adjacent vertebrae includes a first prosthesis plate and a second prosthesis plate. The first and second prosthesis plates each comprise a midline, an engagement surface to engage a first vertebra and a bearing surface disposed opposite the engagement surface. The bearing surfaces of the first and second plates are arranged to cooperate to form an articulate joint. A first region of serrations is disposed on the engagement surface of the first plate on one side of the midline of the first plate, and a second region of serrations is disposed on the engagement surface of the first plate on an opposite side of the first plate midline. Each region comprises at least several serrations, and each serration comprises a base attached to one of the plates and tapers from the base to a tip.
1 . An intervertebral prosthesis for insertion between adjacent vertebrae, the prosthesis comprising:
a first prosthesis plate comprising a midline, an engagement surface to engage a first vertebra and a bearing surface disposed opposite the engagement surface;
a second prosthesis plate comprising a midline, an engagement surface to engage a second vertebra and a bearing surface disposed opposite the engagement surface, wherein the bearing surfaces of the first and second plates are arranged to cooperate to form an articulate joint;
a first region of serrations disposed on the engagement surface of the first plate on one side of the midline of the first plate; and
a second region of serrations disposed on the engagement surface of the first plate on an opposite side of the first plate midline; and
wherein each region comprises at least several serrations and each serration comprises a base attached to one of the plates and tapers from the base to a tip.
2 . The prosthesis according to claim 1 wherein the serrations of the first region are parallel to the serrations of the second region.
3 . The prosthesis according to claim 1 wherein the serrations of the first and second regions are parallel to the midline.
4 . The prosthesis according to claim 1 wherein the serrations of the first and second regions are symmetrically disposed about the midline.
5 . The prosthesis according to claim 1 further comprising a core located between the plates, the core comprising a first surface adapted to engage the bearing surface of the first plate and a second surface adapted to engage the bearing surface of the second plate, wherein the first surface of the core and the bearing surface of the first plate comprise cooperating spherical surfaces.
6 . The prosthesis according to claim, 5 wherein second surface of the core and the bearing surface of the second plate comprise cooperating spherical surfaces.
7 . A prosthesis according to claim 1 further comprising a fin to anchor the first plate in the first vertebra, the fin disposed along the midline between the rows of serrations disposed on the first plate, the fin adapted to enter a cut in the first vertebra.
8 . The prosthesis according to claim 7 , wherein holes are formed transversely through the fin.
9 . The prosthesis according to claim 1 , wherein the bearing surface of each plate is bounded by an annular rim, wherein the annular rims are arranged to contact one another at a predetermined limit of articulate movement of the plates.
10 . The prosthesis according to claim 1 , wherein the bearing surface of each plate is bounded by an annular rim having a groove formed thereon, wherein the grooves are adapted to connect to a placement instrument while the prosthesis is inserted into the intervertebral space.
11 . An intervertebral prosthesis for insertion between adjacent vertebrae, the prosthesis comprising:
a first prosthesis plate comprising a midline, an engagement surface to engage a first vertebra and a bearing surface disposed opposite the engagement surface;
a second prosthesis plate comprising a midline, an engagement surface to engage a second vertebra and a bearing surface disposed opposite the engagement surface, wherein the bearing surfaces of the first and second plates are arranged to cooperate to form an articulate joint;
a first region of serrations disposed on the engagement surface of the first plate on one side of the midline of the first plate;
a second region of serrations disposed on the engagement surface of the first plate on an opposite side of the first plate midline;
a third region of serrations disposed on the engagement surface of the second plate on one side of the midline of the second plate;
a fourth region of serrations disposed on the engagement surface of the second plate on an opposite side of the second plate midline; and
wherein each region comprises at least several serrations and each serration comprises a base attached one of the plates and tapers from the base to a tip.
12 . The prosthesis according to claim 11 wherein the serrations of the third and fourth regions are identical the serrations of the first and second regions, respectively.
13 . The prosthesis according to claim 11 wherein the serrations of the first region are parallel to the serrations of the second region and the serrations of the third region are parallel to the serrations of the fourth region.
14 . The prosthesis according to claim 11 wherein the serrations of the first region and the serrations of the second region are parallel to the first plate midline and the serrations third region and the serrations of the fourth region are parallel to the second plate midline.
15 . The prosthesis according to claim 11 wherein the serrations of the first and second regions are symmetrically disposed about the first plate midline and the serrations of the third and fourth regions are symmetrically disposed about the second plate midline.
16 . The prosthesis according to claim 11 further comprising a core located between the plates, the core comprising a first surface adapted to engage the bearing surface of the first plate and a second surface adapted to engage the bearing surface of the second plate, wherein the first surface of the core and the bearing surface of the first plate comprise cooperating spherical surfaces.
17 . The prosthesis according to claim, 11 wherein second surface of the core and the bearing surface of the second plate comprise cooperating spherical surfaces.
18 . A prosthesis according to claim 11 further comprising:
a first fin to anchor the first plate in the first vertebra, the fin disposed along the midline between the regions of serrations disposed on the first plate, the fin adapted to enter a cut in the first vertebra; and
a second fin to anchor the second plate in the second vertebra, the fin disposed along the midline between the regions of serrations disposed on the second plate, the fin adapted to enter a cut in the second vertebra.
19 . The prosthesis according to claim 18 , wherein holes are formed transversely through the fins.
20 . The prosthesis according to claim 11 , wherein the bearing surface of each plate is bounded by an annular rim, wherein the annular rims are arranged to contact one another at a predetermined limit of articulate movement of the plates.
21 . The prosthesis according to claim 11 , wherein the bearing surface of each plate is bounded by an annular rim having a groove formed thereon, wherein the grooves are adapted to connect to a placement instrument while the prosthesis is inserted into the intervertebral space.