Intervertebral implant with fixation geometry

Abstract

An intervertebral spacer implant ( 80 ) is provided with a retention mechanism ( 86 ) to help alleviate expulsion and movement of the implant when placed in the spine while providing an implant that is easier to insert in the spine. In one embodiment the retention mechanism comprises a keel on at least one of the inferior or superior faces of the spacer implant preferably extending in an anterior-posterior direction. In another embodiment the implant comprises a spacer ( 84 ) and a plate ( 82 ), the plate comprising a supplemental or alternative retention mechanism. In one embodiment the retention mechanism comprises one or more holes ( 88 ) in the anterior end of the plate. In yet another embodiment, the retention mechanism comprises one or more blades that are in a first position when inserted and are preferably rotated to a second position that engages the superior and inferior vertebrae.

1 . (canceled) 
     
     
         2 . An intervertebral implant for implantation between adjacent vertebrae in a spine, the implant comprising:
 a spacer having a superior surface and an inferior surface, a first lateral side surface and a second lateral side surface, the superior surface having a contact area capable of contacting an adjacent upper vertebra and the inferior surface having a contact area capable of contacting an adjacent lower vertebra;   a plate coupled to the spacer, the plate having a superior surface and an inferior surface, a first lateral side surface and a second lateral side surface, and an anterior surface,   wherein the plate has a first screw hole and a second screw hole, the first and second screw holes extend from the anterior surface for receiving a first bone screw and a second bone screw,   wherein the superior surface of the plate has a first keel and the inferior surface of the plate has a second keel, the first and second keels providing resistance to torsion or rotation of the implant, and   wherein the plate includes no further screw holes beyond the first screw hole and the second screw hole for receiving the first and second bone screws.   
     
     
         3 . The implant of  claim 2 , wherein the inferior surface and the superior surface define a through hole, the through hole extending through the spacer. 
     
     
         4 . The implant of  claim 2 , wherein the plate is made from a biocompatible metal. 
     
     
         5 . The implant of  claim 2 , wherein the spacer is made from a biocompatible plastic. 
     
     
         6 . The intervertebral implant of  claim 2 , wherein the implant is bisected by a horizontal plane and the first and second bone screws are inserted at divergent angles to a horizontal plane. 
     
     
         7 . The intervertebral implant of  claim 2 , wherein the implant is bisected by a vertical plane and the first and second bone screws are inserted at convergent angles to a vertical plane. 
     
     
         8 . The implant of  claim 2 , wherein the spacer includes a plurality of protrusions on the superior and inferior surfaces for engaging the adjacent vertebrae. 
     
     
         9 . The implant of  claim 2 , wherein the first and second keels are spaced from the first and second screw holes on the plate. 
     
     
         10 . The implant of  claim 2 , wherein the first and second keels are configured and dimensioned to engage adjacent vertebrae so as to provide resistance to torsion or rotation of the implant. 
     
     
         11 . An intervertebral implant for implantation between adjacent vertebrae in a spine, the implant comprising:
 a spacer having an upper surface and a lower surface, the upper surface including projections to aid in securing the implant to an adjacent vertebra, and the lower surface including projections to aid in securing the implant to an adjacent vertebra; and   a plate coupled to the spacer, the plate having an upper surface, a lower surface, and an anterior surface,   wherein the plate includes first and second screw holes for accepting respective first and second fixation screws designed to penetrate the vertebral bodies and secure the implant in place, the first and second holes extending inward from the anterior surface of the plate,   wherein a first keel extends along the upper surface of the plate and the upper surface of the spacer and a second keel extends along the lower surface of the plate and the lower surface of the spacer, the first and second keels providing resistance to torsion or rotation of the implant, and   wherein the plate includes no further screw holes beyond the first and second screw holes.   
     
     
         12 . An intervertebral implant for implantation in an intervertebral space between adjacent vertebrae, wherein said implant comprises:
 a spacer having an inferior surface and a superior surface, wherein the inferior surface and the superior surfaces each have a contact area capable of engaging with the adjacent vertebrae;   a plate coupled to the spacer, the plate having an anterior surface, an upper surface, a lower surface and at least one hole for receiving a screw;   a locking mechanism disposed on the plate for preventing the back out of at least one screw from the at least one hole,   wherein the spacer includes a plurality of protrusions on the superior and inferior surfaces for engaging the adjacent vertebrae,   wherein the upper surface of the plate further comprises a first extension, the first extension being generally flush with the anterior surface of the plate and the lower surface of the plate comprises a second extension, the second extension being generally flush with the anterior surface of the plate, and   wherein the first and second extension do not include an opening for receiving a screw.   
     
     
         13 . The implant of  claim 12 , wherein the inferior surface and the superior surface define a through hole, the through hole extending through the spacer. 
     
     
         14 . The implant of  claim 12 , wherein the plate is made from a biocompatible metal. 
     
     
         15 . The implant of  claim 12 , wherein the spacer is made from a biocompatible plastic. 
     
     
         16 . The intervertebral implant of  claim 12 , wherein the implant is bisected by a horizontal plane and the first and second bone screws are inserted at divergent angles to a horizontal plane. 
     
     
         17 . The intervertebral implant of  claim 12 , wherein the implant is bisected by a vertical plane and the first and second bone screws are inserted at convergent angles to a vertical plane. 
     
     
         18 . An intervertebral implant for implantation between adjacent vertebrae in a spine, the implant comprising:
 a spacer having a superior surface and an inferior surface, a first lateral side surface and a second lateral side surface, the superior surface having a contact area capable of contacting an adjacent upper vertebra and the inferior surface having a contact area capable of contacting an adjacent lower vertebra;   a plate coupled to the spacer, the plate having a superior surface and an inferior surface, a first lateral side surface and a second lateral side surface, and an anterior surface,   wherein the plate has a first screw hole and a second screw hole, the first and second screw holes extend from the anterior surface for receiving a first bone screw and a second bone screw,   wherein the superior surface of the plate has a first extension and the inferior surface of the plate has a second extension, the first and second extensions are configured and dimensioned to engage the adjacent vertebrae for providing torsional stability,   wherein the plate includes no further screw holes beyond the first screw hole and second screw hole for receiving the first and second bone screws.   
     
     
         19 . The intervertebral implant of  claim 18 , wherein the implant is bisected by a horizontal plane and the first and second bone screws are inserted at divergent angles to a horizontal plane. 
     
     
         20 . The intervertebral implant of  claim 18 , wherein the implant is bisected by a vertical plane and the first and second bone screws are inserted at convergent angles to a vertical plane. 
     
     
         21 . The implant of  claim 18 , wherein the spacer includes a plurality of protrusions on the superior and inferior surfaces for engaging the adjacent vertebrae. 
     
     
         22 . The implant of  claim 18 , the plate further comprising a screw blocking mechanism on the plate, the screw blocking mechanism capable of preventing at least one of the first and second screws from disengaging from the first or second screw holes in the plate. 
     
     
         23 . The implant of  claim 18 , wherein the first and second extensions are spaced from the first and second screw holes on the plate. 
     
     
         24 . The implant of  claim 18 , wherein the first and second screw holes on the plate are located between the adjacent upper and lower vertebrae.