Method and spacer device for spanning a space formed upon removal of an intervertebral disc

Abstract

An intervertebral spacer is designed particularly for patients who are not candidates for total disc replacement. The intervertebral 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 intervertebral 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 within the vertebral body contacting surfaces to provide increased bone on growth surfaces and to prevent subsidence.

What is claimed is: 
     
         1 . A method of spanning a space formed upon removal of an intervertebral disc, the method comprising:
 performing a discectomy to remove disc material between two adjacent vertebral bodies;   cutting at least one slot in at least one of the adjacent vertebrae;   placing an intervertebral spacer between the two adjacent vertebral bodies, the intervertebral spacer including:
 two end plates, each end plate having a metallic vertebral body contacting surface, an inner surface, and a fin extending from the vertebral body contacting surface; 
 a connector interconnecting the inner surfaces of the two end plates in a rigid manner which limits motion between the end plates to less than a total of 5 degrees; 
 wherein the vertebral body contacting surfaces of one of the two end plates has at least one through hole therein that covers less than 40 percent of the vertebral body contacting surfaces, and wherein the at least one through hole therein extends longitudinally from one side of each end plate through the end plate to the other side of the end plate for bone growth therein, 
 wherein the intervertebral spacer including the two end plates and connector is formed of a single piece; 
   placing a fin on one of the vertebral body contacting surfaces into the at least one slot, whereby the intervertebral spacer is inhibited from rotating; and   maintaining the disc spaced between the two adjacent vertebral bodies with the intervertebral spacer without the use of bone graft or bridging bone, wherein no part of the intervertebral spacer extends outside the slot.   
     
     
         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 the connector include a metal. 
     
     
         4 . The method of  claim 1 , wherein the intervertebral spacer fills at least 50 percent of a vertebral space formed between the vertebral bodies when the intervertebral spacer is positioned between the two vertebral bodies. 
     
     
         5 . The method of  claim 1 , wherein the holes of the vertebral body contacting surface of the end plates cover less than 25 percent of the vertebral body contacting surfaces. 
     
     
         6 . The method of  claim 1 , further comprising at least one additional coupling component provided on the vertebral body contacting surfaces of the intervertebral spacer. 
     
     
         7 . The method of  claim 6 , wherein the additional coupling component includes at least one of a screw, teeth, serrations or grooves. 
     
     
         8 . The method of  claim 1 , wherein the two adjacent vertebral bodies are stabilized without the use of external plates or screws. 
     
     
         9 . The method of  claim 1 , wherein the connector includes a solid cylindrical member. 
     
     
         10 . The method of  claim 1 , wherein the two end plates and connector are formed of a single piece of PEEK with metallic vertebral body contacting surfaces. 
     
     
         11 . An intervertebral spacer for spanning a space formed by upon removal of an intervertebral disc, the intervertebral spacer comprising:
 two end plates sized and shaped to fit within an intervertebral space between two vertebrae, each end plate having a vertebral body contacting surface and an inner surface,   wherein the vertebral body contacting surfaces of one of the two end plates has at least one through hole therein that covers less than 40 percent of the vertebral body contacting surfaces, and wherein the at least one through hole therein extends longitudinally from one side of each end plate through the end plate to the other side of the end plate for bone growth therein;   a connector interconnecting the inner surfaces of the two end plates in a rigid manner which limits motion between the end plates to less than a total of 5 degrees; and   at least one fin projecting from one of the vertebral contacting surfaces, wherein the fin is configured to be inserted into a slot cut in the vertebra to inhibit rotation of the intervertebral spacer with respect to the vertebra.   
     
     
         12 . The intervertebral spacer of  claim 11 , wherein the two end plates and connector are formed of a single piece of PEEK with metallic screens or metallic coatings formed directly on the PEEK to provide the vertebral body contacting surfaces. 
     
     
         13 . The intervertebral spacer of  claim 11 , wherein the intervertebral spacer is configured such that when placed within the intervertebral space no part of the intervertebral spacer extends outside the intervertebral disc space and slot. 
     
     
         14 . The intervertebral spacer of  claim 11 , further comprising at least one additional coupling component provided on the vertebral body contacting surfaces. 
     
     
         15 . The intervertebral spacer of  claim 14 , wherein the additional coupling component includes at least one of a screw, teeth, serrations or grooves. 
     
     
         16 . The intervertebral spacer of  claim 11 , wherein the two end plates and the connector include a metal. 
     
     
         17 . A method of spanning a space formed upon removal of an intervertebral disc, the method comprising:
 performing a discectomy to remove disc material between two adjacent vertebral bodies;   cutting at least one slot in at least one of the adjacent vertebrae;   placing an intervertebral spacer between the two adjacent vertebral bodies, the intervertebral spacer including:   two end plates, each end plate having a metallic vertebral body contacting surface, an inner surface and a fin extending from the vertebral body contacting surface;   a connector interconnecting the inner surfaces of the two end plates in a rigid manner to limits motion between the end plates;   wherein the vertebral body contacting surfaces of one of the two end plates has at least one through hole therein, wherein the at least one through hole therein extends longitudinally from one side of each end plate through the end plate to the other side of the end plate for bone growth therein;   placing a fin on one of the vertebral body contacting surfaces into the at least one slot, whereby the intervertebral spacer is inhibited from rotating; and   maintaining the disc spaced between the two adjacent vertebral bodies with the intervertebral spacer without the use of bone graft or bridging bone.   
     
     
         18 . The method of  claim 17 , further comprising at least one additional coupling component provided on the vertebral body contacting surfaces of the intervertebral spacer. 
     
     
         19 . The method of  claim 17 , wherein the connector includes a solid cylindrical member. 
     
     
         20 . The method of  claim 17 , wherein the two end plates and connector are formed of a single piece of PEEK with metallic vertebral body contacting surfaces.