Intervertebral allograft spacer

Abstract

An allogenic intervertebral implant for fusing vertebrae is disclosed. The implant is a piece of allogenic bone conforming in size and shape with a portion of an end plate of a vertebra. The implant has a wedge-shaped profile to restore disc height and the natural curvature of the spine. The top and bottom surfaces of the implant have a plurality of teeth to resist expulsion and provide initial stability. The implant according to the present invention provides initial stability need for fusion without stress shielding.

1 . An intervertebral allograft implant for implantation between adjacent first and second vertebrae, each of the first and second vertebrae including an end-plate, the implant comprising: 
 a superior surface sized and configured to contact at least a portion of the end-plate of the first vertebra,    an inferior surface sized and configured to contact at least a portion of the end-plate of the second vertebrae,    a front surface extending from the superior surface to the inferior surface;    a back surface extending from the superior surface to the inferior surface, and    a pair of lateral surfaces extending from the superior surface to the inferior surface and extending from the front surface to the back surface;    wherein the implant is formed from at least two pieces of bone joined together to form a single body.    
   
   
       2 . The implant of  claim 1 , wherein the plurality of bone pieces have mating interlocking surfaces that aid in holding the pieces together.  
   
   
       3 . The implant of  claim 1 , further comprising at least one pin extending through an opening formed in the plurality of bone pieces to hold the pieces together.  
   
   
       4 . The implant of  claim 1 , wherein the pin intersects the superior and inferior surfaces at an oblique angle.  
   
   
       5 . The implant of  claim 1 , wherein the implant includes a top piece joined to a bottom piece, the top piece including the superior surface for contacting the first vertebra and a first connecting surface, the bottom piece including the inferior surface for contacting the second vertebra and a second connecting surface, the first connecting surface being sized and configured to contact the second connecting surface so that the top and bottom pieces are stacked one on top of the other.  
   
   
       6 . The implant of  claim 5 , wherein the first and second connecting surfaces include a plurality of interconnecting ridges and grooves to interlock the top and bottom pieces.  
   
   
       7 . The implant of  claim 5 , wherein the top and bottom pieces each include at least one bore formed at least partially therein, the at least one bore being sized and configured to receive at least one pin for further securing the top piece to the bottom piece.  
   
   
       8 . The implant of  claim 1 , wherein the implant includes a first lateral piece and a second lateral piece, each of the first and second lateral pieces including at least a portion of the superior and inferior surfaces for contacting the first and second vertebra respectively, the first lateral piece further including a first connecting surface and the second lateral piece further including a second connecting surface, the first connecting surface being sized and configured to contact the second connecting surface so that the first and second lateral pieces are arranged in a side by side configuration.  
   
   
       9 . The implant of  claim 1 , wherein the implant comprises a first lateral piece joined to a second lateral piece, wherein the first and second lateral pieces are substantially C-shaped so that when joined side by side they define a central bore.  
   
   
       10 . The implant of  claim 1 , wherein the implant is formed by at least three pieces of bone.  
   
   
       11 . The implant of  claim 1 , wherein the pair of lateral surfaces each have a length extending from the front surface to the back surface and wherein the front and back surfaces each have a length extending between the pair of lateral surfaces, the length of the lateral surfaces being at least approximately twice as long as the length of the front and back surfaces.  
   
   
       12 . The implant of  claim 1 , wherein the pair of lateral surfaces each have a length extending from the front surface to the back surface and wherein the front and back surfaces each have a length extending between the pair of lateral surfaces, the length of the lateral surfaces being at least approximately half as long as the length of the front and back surfaces.  
   
   
       13 . The implant of  claim 1 , wherein the superior and inferior surfaces include a plurality of teeth.  
   
   
       14 . The implant of  claim 13 , wherein the teeth have a pyramidal-shape.  
   
   
       15 . The implant of  claim 13 , wherein the teeth have a saw tooth shape.  
   
   
       16 . The implant of  claim 1 , wherein each of the lateral surfaces includes a channel for engaging a surgical instrument.  
   
   
       17 . The implant of  claim 1 , further comprising a threaded hole formed in one of the front, back or lateral surfaces for receiving a surgical instrument.  
   
   
       18 . The implant of  claim 1 , wherein the superior and inferior surfaces include a wedge-shaped profile so that the body has a gradual decreasing height.  
   
   
       19 . The implant of  claim 1 , wherein the superior and inferior surfaces are curved to substantially match the contours of the end-plates.  
   
   
       20 . The implant of  claim 1 , wherein the implant includes at least one rounded edge along a perimeter of the superior and inferior faces for facilitating insertion of the implant in-between the first and second vertebrae.  
   
   
       21 . The implant of  claim 1 , wherein the implant includes a hollow bore extending from the superior surface to the inferior surface.  
   
   
       22 . An intervertebral allograft implant for implantation between adjacent first and second vertebrae, each of the first and second vertebrae including an end-plate, the implant comprising: 
 a superior surface sized and configured to contact at least a portion of the end-plate of the first vertebra,    an inferior surface sized and configured to contact at least a portion of the end-plate of the second vertebrae,    a front surface extending from the superior surface to the inferior surface;    a back surface extending from the superior surface to the inferior surface, and    a pair of lateral surfaces extending from the superior surface to the inferior surface and extending from the front surface to the back surface;    wherein the implant is formed from at least a first lateral piece joined to a second lateral piece to form a single body, the first and second lateral pieces being sized and configured so that when joined side by side they define a central bore, the central bore extending from the superior surface to the inferior surface.    
   
   
       23 . An intervertebral allograft implant for implantation between adjacent first and second vertebrae, each of the first and second vertebrae including an end-plate, the implant comprising: 
 a superior surface sized and configured to contact at least a portion of the end-plate of the first vertebra,    an inferior surface sized and configured to contact at least a portion of the end-plate of the second vertebrae,    a front surface extending from the superior surface to the inferior surface;    a back surface extending from the superior surface to the inferior surface, and    a pair of lateral surfaces extending from the superior surface to the inferior surface and extending from the front surface to the back surface;    wherein the implant is formed from at least a top piece joined to a bottom piece to form a single body, the top piece including the superior surface for contacting the first vertebra and a first connecting surface, the bottom piece including the inferior surface for contacting the second vertebra and a second connecting surface, the first connecting surface being sized and configured to contact the second connecting surface so that the top and bottom pieces are stacked one on top of the other.    
   
   
       24 . An intervertebral allograft implant for implantation between adjacent first and second vertebrae, each of the first and second vertebrae including an end-plate, the implant comprising: 
 a superior surface sized and configured to contact at least a portion of the end-plate of the first vertebra,    an inferior surface sized and configured to contact at least a portion of the end-plate of the second vertebrae,    a front surface extending from the superior surface to the inferior surface;    a back surface extending from the superior surface to the inferior surface, and    a pair of lateral surfaces extending from the superior surface to the inferior surface and extending from the front surface to the back surface;    wherein the pair of lateral surfaces each have a length extending from the front surface to the back surface and wherein the front and back surfaces each have a length extending between the pair of lateral surfaces, the length of the lateral surfaces being at least approximately twice as long as the length of the front and back surfaces.    
   
   
       25 . An intervertebral allograft implant for implantation between adjacent first and second vertebrae, each of the first and second vertebrae including an end-plate, the implant comprising: 
 a superior surface sized and configured to contact at least a portion of the end-plate of the first vertebra,    an inferior surface sized and configured to contact at least a portion of the end-plate of the second vertebrae,    a front surface extending from the superior surface to the inferior surface;    a back surface extending from the superior surface to the inferior surface, and    a pair of lateral surfaces extending from the superior surface to the inferior surface and extending from the front surface to the back surface;    wherein the superior and inferior surfaces include a plurality of teeth.