Method and Spacer Device for Spanning a Space Formed upon Removal of an Intervertebral Disc
An intervertebral spacer is designed particularly for patients who are not candidates for total disc replacement. The spacer maintains disc height and prevents subsidence with a large vertebral body contacting surface area while substantially reducing recovery time by eliminating the need for bridging bone. The intervertebral spacer or fusion spacer includes a rigid spacer body sized and shaped to fit within an intervertebral space between two vertebral bodies. In one embodiment, the spacer body has two opposed metallic vertebral contacting surfaces, at least one fin extending from each of the vertebral contacting surfaces and configured to be positioned within slots cut into the two vertebral bodies. Holes, if present, cover less than 40 percent of the entire vertebral body contacting surfaces to provide increased bone ongrowth surfaces and to prevent subsidence.
1 . A method of spanning a space formed by upon removal of an intervertebral disc, the method comprising:
performing a discectomy to remove disc material between two adjacent vertebral bodies;
placing an intervertebral spacer between the two adjacent vertebral bodies, the spacer comprising two end plates, each end plate having a metallic vertebral body contacting surface and an inner surface, and a connector interconnecting the inner surfaces of the two end plates in a rigid manner which limits motion between the plates to less than a total of 5 degrees, wherein the vertebral body contacting surfaces of the end plates have no holes therein or have holes which cover less than 40 percent of the vertebral body contacting surfaces; and
maintaining the disc space between the two adjacent vertebral bodies with the intervertebral spacer without the use of bone graft or bridging bone.
2 . The method of claim 1 , wherein the connector is a rigid connector.
3 . The method of claim 1 , wherein the two end plates and connector are formed of a single piece of metal.
4 . The method of claim 1 , wherein the intervertebral spacer is selected, such that when the spacer is positioned between the two vertebral bodies the spacer fills at least 50 percent of a vertebral space formed between the vertebral bodies.
5 . The method of claim 1 , wherein the vertebral body contacting surface of the end plates has holes which cover less than 25 percent of the vertebral body contacting surfaces.
6 . The method of claim 1 , further comprising cutting at least one slot in each of the adjacent vertebrae and placing a fin into the at least one slot.
7 . The method of claim 6 , further comprising at least one additional fixation means provided on the vertebral body contacting surfaces the intervertebral spacer.
8 . The method of claim 7 , wherein the additional fixation means is at least one of a screw, teeth, serrations or grooves.
9 . The method of claim 1 , wherein the metallic vertebral contacting surface is formed of titanium or a titanium alloy.
10 . An intervertebral spacer for spanning a space formed by upon removal of an intervertebral disc, the spacer comprising:
two end plates sized and shaped to fit within an intervertebral space, each end plate having a metallic vertebral contacting surface and an inner surface;
a connector interconnecting the inner surfaces of the two end plates in a rigid manner which limits motion between the plates to less than a total of 5 degrees; and
wherein the vertebral body contacting surfaces of the end plates have no holes therein or have holes which cover less than 40 percent of the vertebral body contacting surfaces.
11 . The spacer of claim 10 , wherein the connector is a rigid connector.
12 . The spacer of claim 10 , wherein the two end plates and connector are formed of a single piece of metal.
13 . The spacer of claim 10 , wherein the vertebral body contacting surface of the end plates has holes which cover less than 25 percent of the vertebral body contacting surfaces.
14 . The spacer of claim 10 , further comprising at least one fin extending from the vertebral contacting surfaces.
15 . The spacer of claim 10 , wherein the two end plates and connector are formed of PEEK with metallic screens, layers or coatings on the vertebral body contacting surfaces.
16 . The spacer of claim 10 , wherein the metallic vertebral contacting surface is formed of titanium or a titanium alloy.
17 . A method of performing an anterior/posterior fusion, the method comprising:
performing a discectomy to remove disc material between two adjacent vertebral bodies;
placing an intervertebral spacer between the two adjacent discs, the spacer comprising two end plates, each end plate having a metallic vertebral contacting surface and an inner surface, and a rigid connector interconnecting the inner surfaces of the two end plates, wherein the vertebral body contacting surfaces of the end plates have no holes therein or have holes which cover less than 40 percent of the vertebral body contacting surfaces;
maintaining the disc space between the two adjacent discs with the intervertebral spacer; and
posteriorly placing a stabilization system to fix the angle between the vertebral bodies.
18 . The method of claim 17 , wherein the intervertebral spacer is placed anteriorly.
19 . The method of claim 17 , wherein the intervertebral spacer is place posteriorly.
20 . The method of claim 19 , wherein the posteriorly placed intervertebral spacer includes a two part spacer in which the two parts together cover about 40 percent or more of the vertebral surface.
21 . The method of claim 19 , wherein the posteriorly placed stabilization system includes at least one screw placed into each of the vertebral bodies and at least one connector therebetween.
22 . The method of claim 19 , wherein the method is performed without the use of bone graft.
23 . The method of claim 19 , wherein the vertebral body contacting surfaces of the end plates have holes which cover less than 25 percent of the vertebral body contacting surfaces.
24 . A fusion system, the system comprising:
an intervertebral spacer comprising:
two end plates sized and shaped to fit within an intervertebral space, each end plate having a vertebral contacting surface an inner surface, wherein the vertebral body contacting surfaces of the end plates have no holes therein or have holes which cover less than 40 percent of the vertebral body contacting surfaces; and
a rigid connector interconnecting the inner surfaces of the two end plates; and
a posteriorly placed stabilization system including at least two screws configured to be placed into the vertebral bodies and at least one connector therebetween.
25 . The system of claim 24 , wherein the intervertebral spacer is a unitary spacer sized to be placed anteriorly.
26 . The system of claim 24 , wherein the intervertebral spacer is a two part spacer sized to be place posteriorly.
27 . The system of claim 24 , wherein the vertebral body contacting surfaces of the end plates have holes which cover less than 25 percent of the vertebral body contacting surfaces.
28 . A fusion spacer comprising:
a rigid spacer body sized and shaped to fit within an intervertebral space between two vertebral bodies, the body having two opposed metallic vertebral contacting surfaces;
at least one fin extending from each of the vertebral contacting surfaces, the fins configured to be positioned within slots cut into the two vertebral bodies;
a plurality of serrations on the vertebral contacting surfaces; and
wherein holes cover less than 40 percent of the entire vertebral body contacting surfaces.
29 . The spacer of claim 28 , wherein holes cover less than 25 percent of the vertebral body contacting surfaces.
30 . The spacer of claim 28 , wherein the metallic vertebral contacting surfaces are formed of titanium or a titanium alloy.
31 . The spacer of claim 30 , wherein the body is a unitary metallic body.
32 . The spacer of claim 30 , wherein the body is formed of PEEK.