Intervertebral Implant for Transforminal Posterior Lumbar Interbody Fusion Procedure

Abstract

An intervertebral implant for fusing vertebrae is disclosed. The implant may have a body with curved, posterior and anterior faces separated by two narrow implant ends, superior and inferior faces having a plurality of undulating surfaces for contacting vertebral endplates, and at least one depression in the anterior or posterior face for engagement by an insertion tool. The implant may also have one or more vertical through-channels extending through the implant from the superior face to the inferior face, a chamfer on the superior and inferior surfaces at one of the narrow implant ends, and/or a beveled edge along a perimeter of the superior and inferior faces. The implant configuration facilitates transforaminal insertion of the implant into a symmetric position about the midline of the spine so that a single implant provides balanced support to the spinal column. The implant may be formed of a plurality of interconnecting bodies assembled to form a single unit. An implantation kit and method are also disclosed.

1 . An intervertebral implant sized and configured for implantation between a first and second vertebra via transforaminal lumbar interbody fusion technique, the implant comprising: 
 a body substantially made of allograft, the body including a curved posterior face, a curved anterior face, both curved posterior and anterior faces extending along a longitudinal axis of the implant;    a pair of narrow ends separating the posterior and anterior faces and superior and inferior surfaces for contacting at least a portion of the first and second vertebral, the superior and inferior surfaces include a plurality of teeth formed; and    at least one non-threaded, horizontal channel configured and adapted for engagement by an implant insertion tool, the channel disposed along at least a portion of the curved posterior face or disposed along at least a portion of the curved anterior face.    
     
     
         2 . The implant of  claim 1 , further comprising at least one vertical through-channel extending from said superior surface to said inferior surface.  
     
     
         3 . The implant of  claim 1 , wherein at least one of the superior and inferior surfaces includes a chamfer formed thereon.  
     
     
         4 . The implant of  claim 3 , wherein the chamfer is devoid of any teeth formed thereon.  
     
     
         5 . The implant of  claim 3 , wherein the implant includes a pair of non-threaded, horizontal channels, one of said non-threaded, horizontal channel being formed on the curved posterior face, the other of said non-threaded, horizontal channel being formed on the curved anterior face, the pair of non-threaded, horizontal channels extending from one of the arcuate ends.  
     
     
         6 . The implant of  claim 5 , wherein the chamfer is formed on the other of said arcuate ends.  
     
     
         7 . The implant of  claim 1 , wherein the curved anterior and curved posterior faces are substantially parallel.  
     
     
         8 . The implant of  claim 6 , wherein the curved posterior face has a radii of curvature R 1  and the curved anterior face has a radii of curvature R 2 , wherein R 1  is between about 25 mm and 35 mm and R 2  is between about 15 mm and 25 mm.  
     
     
         9 . The implant of  claim 1 , wherein the teeth have a pyramid shape such that each tooth has four sides and forms an acute angle with the superior or inferior faces.  
     
     
         10 . The implant of  claim 1 , wherein a distance between the superior and inferior surfaces define an implant height, the implant height being greatest at a midsection between the pair of narrow ends, the implant height tapering gradually along the longitudinal axis of the implant so that the implant height is thinnest at the narrow ends of the implant.  
     
     
         11 . The implant of  claim 10 , wherein the tapering thickness is defined by a radius of curvature R 3 , wherein R 3  is between about 85 mm and 115 mm.  
     
     
         12 . The implant of  claim 10 , wherein the implant height is substantially constant for any given cross section taken perpendicular to the longitudinal axis of the implant  
     
     
         13 . The implant of  claim 1 , wherein the implant is formed of at least two pieces of allograft assembled together to form the implant.  
     
     
         14 . The implant of  claim 13 , wherein the at least two pieces of allograft are joined together by interlocking grooves and pallets.  
     
     
         15 . The implant of  claim 13 , wherein the at least two pieces of allograft containing an opening formed therein, the opening being sized and configured to receive at least one pin for holding the pieces of allograft together as a single unit.  
     
     
         16 . An intervertebral implant sized and configured for implantation between a first and second vertebra via transforaminal lumbar interbody fusion technique, the implant comprising: 
 a body having a curved posterior face, a curved anterior face, a pair of curved ends separating the posterior and anterior faces and superior and inferior faces for contacting at least a portion of the first and second vertebra, the superior and inferior faces defining a thickness of the implant;    wherein the body includes at least one vertical through-channel extending from the superior face to the inferior face; and    the anterior and posterior faces include at least two non-threaded, horizontal channels configured and adapted for engagement by an implant insertion tool, one of the channels being disposed along at least a portion of the curved posterior face, the other of said channels being disposed along at least a portion of the curved anterior face, wherein the channels each include at least two recesses for engaging a corresponding projection formed on the insertion tool.    
     
     
         17 . The implant of  claim 16 , wherein the at least one vertical through-channel defines a first wall between the anterior face and the vertical through-channel and a second wall between the posterior face and the vertical through channel, the first and second walls having a wall width, the vertical through channel having a channel width, the wall width being greater than the channel width.  
     
     
         18 . The implant of  claim 16 , wherein the implant includes at least two vertical through-channels extending from said superior surface to said anterior surface.  
     
     
         19 . The implant of  claim 16 , wherein the implant further includes at least one horizontal through-channel extending through the implant from the anterior face to the posterior face.  
     
     
         20 . The implant of  claim 16 , wherein the implant further includes at least one lateral through-channel extending from at least one of the curved ends towards the vertical through channel.  
     
     
         21 . The implant of  claim 20 , wherein the lateral through channel extends from one curved end completely through the implant to the other curved end.  
     
     
         22 . The implant of  claim 16 , wherein the implant is formed from a radiolucent material.  
     
     
         23 . The implant of  claim 20 , wherein the implant includes at least one radiopaque marker  
     
     
         24 . The implant of  claim 16 , wherein the implant is formed from a titanium alloy.  
     
     
         25 . The implant of  claim 16  wherein at least one of the superior and inferior surfaces includes a chamfer formed thereon.  
     
     
         26 . The implant of  claim 25 , wherein the chamfer is devoid of any teeth formed thereon.  
     
     
         27 . The implant of  claim 16 , wherein the implant further includes a beveled edge along a perimeter of the superior and inferior surfaces.  
     
     
         28 . An intervertebral implant for posterior insertion via a transforaminal window comprising: 
 curved, substantially parallel posterior and anterior faces, the posterior and anterior faces extending along a longitudinal axis of the implant;    a pair of convex narrow ends separating the posterior and anterior faces;    superior and inferior faces for contacting upper and lower vertebral endplates, the superior and inferior faces defining a thickness of the implant; 
 at least one depression in the anterior or posterior face for engagement by an insertion tool; and  
 at least two vertical through-channels extending through the implant from the superior face to the inferior face, each vertical through-channel having a width and walls on posterior and anterior sides of the width, the walls on the posterior and anterior sides of the width of the vertical through-channels having a thickness greater than the width of the vertical through channels;  
   
     
     
         29 . The implant of  claim 28 , further comprising a chamfer on the superior and inferior faces at one of the convex narrow ends to facilitate implant insertion.  
     
     
         30 . The implant of  claim 28 , wherein the depression further comprises multiple recesses for engagement with an insertion tool.  
     
     
         31 . The implant of  claim 28 , wherein the implant further includes at least one horizontal through-channel extending through the implant from the anterior face to the posterior face.  
     
     
         32 . The implant of  claim 28 , wherein the implant further includes at least one lateral through-channel extending from at least one of the curved ends towards the vertical through channel.  
     
     
         33 . The implant of  claim 32 , wherein the lateral through channel extends from one curved end completely through the implant to the other curved end.  
     
     
         34 . The implant of  claim 28 , wherein the implant is formed from a radiolucent material.  
     
     
         35 . The implant of  claim 34 , wherein the implant includes at least one radiopaque marker.  
     
     
         36 . The implant of  claim 28 , wherein the implant is formed from a titanium alloy.  
     
     
         37 . An intervertebral implant sized and configured for implantation between a first and second vertebra via transforaminal lumbar interbody fusion technique, the implant comprising: 
 curved posterior and anterior faces, the posterior and anterior faces extending along a longitudinal axis of the implant;    a pair of arcuate ends separating the posterior and anterior faces;    superior and inferior surfaces for contacting at least a portion of the first and second vertebral, the superior and inferior faces defining a thickness of the implant;    at least one vertical through-channel extending from the superior surface to the inferior surface, the at least one vertical through-channel defining a first wall between the anterior face and the vertical through-channel and a second wall between the posterior face and the vertical through channel, the first and second walls having a wall width, the vertical through channel having a channel width, the wall width being greater than the channel width.