Universal Spinal Disc Implant System

Abstract

A revisable intervertebral implant may include two end plates designed to detachably receive a variety of intermediate components including articulating bearing inserts, elastic inserts, and fusion blocks. Each intermediate component may be secured to a snap insert that snaps into engagement with the corresponding end plate in response to pressure urging the intermediate component toward the end plate along a cephalad-caudal direction. The end plates may first be secured to the corresponding vertebral bodies, and then the intermediate component(s) may be snapped into locking engagement with the implanted end plates to complete in-situ assembly of the intervertebral implant. The implant may easily be revised by snapping the intermediate component(s) out of engagement with the end plates, removing the intermediate component(s), inserting the new intermediate component(s) into the space between the end plates, and snapping the new intermediate component(s) into engagement with the end plates.

1 . An intervertebral implant comprising:
 a first end plate configured to be secured to a first vertebral body adjacent to an intervertebral space; and   a first intermediate component configured to be lockable into a locked position relative to the first end plate in response to motion between the first intermediate component and the first end plate, wherein the first intermediate component comprises a concave articular surface.   
     
     
         2 . The intervertebral implant of  claim 1 , wherein the first intermediate component is positionable in a free position relative to the first end plate, wherein in the free position, relative motion between the first intermediate component and the first end plate is unrestricted, wherein the first intermediate component is movable between the locked and free positions along a straight pathway having a length of 6 millimeters or less. 
     
     
         3 . The intervertebral implant of  claim 2 , wherein a first force required to lock the first intermediate component into the locked position relative to the first end plate is less than a second force required to move the first intermediate component from the locked position to the free position relative to the first end plate. 
     
     
         4 . The intervertebral implant of  claim 1 , wherein a force required to lock the first intermediate component into the locked position relative to the first end plate is 20 pounds or less. 
     
     
         5 . The intervertebral implant of  claim 1 , wherein the first intermediate component is further configured to be locked in response to motion of the first intermediate component toward the first end plate along a cephalad-caudal path. 
     
     
         6 . The intervertebral implant of  claim 1 , further comprising:
 a second end plate configured to be secured to a second vertebral body adjacent to the intervertebral space; and   a second intermediate component configured to be lockable into a locked position relative to the second end plate in response to motion between the second intermediate component and the second end plate, wherein the second intermediate component comprises a convex articular surface shaped to articulate with the concave articular surface.   
     
     
         7 . The intervertebral implant of  claim 1 , further comprising a snap fastener separate from the first end plate and the first intermediate component, wherein the snap fastener is shaped to be secured to the first intermediate component and to snap into engagement with the first end plate. 
     
     
         8 . An intervertebral implant comprising:
 a first end plate configured to be secured to a first vertebral body adjacent to an intervertebral space; and   a first intermediate component configured to be reversibly lockable into a locked position relative to the first end plate in response to motion of the first intermediate component toward the first end plate along a cephalad-caudal path.   
     
     
         9 . The intervertebral implant of  claim 8 , wherein the first intermediate component further comprises a free position relative to the first end plate, wherein in the free position, relative motion between the first intermediate component and the first end plate is unrestricted, wherein the first intermediate component is movable between the locked and free positions along a straight pathway having a length of 6 millimeters or less. 
     
     
         10 . The intervertebral implant of  claim 9 , wherein a first force required to lock the first intermediate component into the locked position relative to the first end plate is less than a second force required to move the first intermediate component from the locked position to the free position relative to the first end plate. 
     
     
         11 . The intervertebral implant of  claim 8 , wherein a force required to lock the first intermediate component into the locked position relative to the first end plate is 20 pounds or less. 
     
     
         12 . The intervertebral implant of  claim 8 , further comprising:
 a second end plate configured to be secured to a second vertebral body adjacent to the intervertebral space; and   a second intermediate component configured to be lockable into a locked position relative to the second end plate in response to motion between the second intermediate component and the second end plate, wherein the second intermediate component comprises a convex articular surface shaped to articulate with the concave articular surface.   
     
     
         13 . The intervertebral implant of  claim 12 , further comprising a third intermediate component configured to be lockable into a locked position relative to the first and second end plates in response to motion between the third intermediate component and the first and second end plates, wherein the third intermediate component comprises a fusion block configured to substantially prevent relative motion between the first and second end plates. 
     
     
         14 . The intervertebral implant of  claim 8 , further comprising a snap fastener separate from the first end plate and the first intermediate component, wherein the snap fastener is shaped to be secured to the first intermediate component and to snap into engagement with the first end plate. 
     
     
         15 . A method of implanting an intervertebral implant on a spine comprising a first vertebral body adjacent to an intervertebral space, the method comprising:
 securing a first end plate to the first vertebral body;   moving a first intermediate component to a locked position relative to the first end plate, the first intermediate component comprising a concave articular surface; and   locking the first intermediate component in the locked position relative to the first end plate in response to the relative motion.   
     
     
         16 . The method of  claim 15 , wherein moving the first intermediate component to the locked position comprises moving the first intermediate component from a free position along a straight pathway to the locked position, the straight pathway having a length of 6 millimeters or less, wherein, in the free position, relative motion between the first intermediate component and the first end plate is unrestricted. 
     
     
         17 . The method of  claim 16 , wherein moving the first intermediate component to the locked position comprises exerting a first force on the first intermediate component, wherein the first force is less than a second force that would be required to move the first intermediate component from the locked position to the free position. 
     
     
         18 . The method of  claim 15 , wherein moving the first intermediate component to the locked position comprises exerting a first force on the intermediate component, wherein the first force is 20 pounds or less. 
     
     
         19 . The method of  claim 15 , wherein moving the first intermediate component to the locked position comprises moving the first intermediate component toward the first end plate along a cephalad-caudal path. 
     
     
         20 . The method of  claim 15 , further comprising:
 securing a second end plate to a second vertebral body adjacent to the intervertebral space; and   moving a second intermediate component to a locked position relative to the second end plate, the second intermediate component comprising a convex articular surface shaped to articulate with the concave articular surface; and   locking the second intermediate component in the locked position relative to the second end plate in response to the relative motion.