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 - 25 . (canceled) 
     
     
         26 . An intervertebral implant comprising:
 a spacer having a first insertion end portion, a second end portion opposite the first insertion end portion, a first lateral side portion, a second lateral side portion, an upper surface, and a lower surface, the spacer configured and dimensioned for insertion between vertebrae;   a plate secured to the second end portion of the spacer, the plate including at least two through holes defining first and second central hole axes, the at least two through holes configured and dimensioned to receive bone screws for securing the implant to adjacent vertebrae, the first through hole exits through the upper surface of the spacer, the second through hole exits through the lower surface of the spacer, the first and second central hole axes form non-zero angles with respect to the upper and lower surfaces of the spacer; and   at least one keel formed on at least one of the upper and lower surfaces of the spacer wherein the at least one keel extends from the first insertion end portion of the spacer towards the second end portion of the spacer at least about 50 percent of a distance from the first insertion end portion to the second end portion.   
     
     
         27 . The implant according to  claim 26 , wherein the keel extends at least about 80 percent of the distance from the first insertion end portion to the second end portion. 
     
     
         28 . The intervertebral implant of  claim 27 , wherein the keel extends at least about 95 percent of the distance from the first insertion end portion to the second end portion. 
     
     
         29 . The intervertebral implant of  claim 26 , wherein the keel includes a first insertion end and a second end, the first insertion end is wedge shaped. 
     
     
         30 . The intervertebral implant of  claim 26 , wherein the keel includes a plurality of projections formed on a top surface thereof, the projections having a saw-tooth shape. 
     
     
         31 . The intervertebral implant of  claim 26 , wherein the keel includes a first insertion end and a second end portion, the first insertion end of the keel being substantially aligned with the first insertion end portion of the spacer. 
     
     
         32 . The intervertebral implant of  claim 26 , wherein the keel includes a first insertion end and a second end portion, the keel is tapered so that the keel is higher at the second end portion relative to the first insertion end. 
     
     
         33 . The implant of  claim 26 , wherein the plate is formed of a different material than the spacer. 
     
     
         34 . The implant of  claim 33 , wherein the plate is formed of a metallic material and the spacer is formed of a non-metallic material. 
     
     
         35 . The implant of  claim 34 , wherein the plate does not extend beyond a perimeter of the spacer. 
     
     
         36 . The implant of  claim 35 , wherein a height of the plate is no more than a height of the spacer at the second end portion so that the plate does not increase a height profile of the spacer. 
     
     
         37 . The implant of  claim 34 , wherein the plate includes an outer surface, the through holes formed in the plate being configured such that the first and second central hole axes are generally aligned along a straight line at the outer surface of the plate, the straight line generally corresponding with a mid-plane of the implant. 
     
     
         38 . The implant of  claim 34 , wherein the spacer and the plate are secured together by at least one dovetail connection. 
     
     
         39 . The implant of  claim 38 , wherein the dovetail connection extends from the upper surface to the lower surface. 
     
     
         40 . The implant of  claim 33 , wherein the keel is formed only on the spacer. 
     
     
         41 . The implant of  claim 26 , wherein the spacer is solid. 
     
     
         42 . The implant of  claim 26 , wherein the spacer includes a plurality of windows. 
     
     
         43 . The implant of  claim 26 , wherein the spacer includes a plurality of projections formed on at least one of the upper and lower surfaces, the projections having a height less than a height of the keel. 
     
     
         44 . The implant of  claim 26 , wherein the keel has a height of about 1 mm to about 3.5 mm and a width of about 0.5 mm to about 3 mm. 
     
     
         45 . An intervertebral implant comprising:
 a spacer having a first insertion end portion, a second end portion, an upper surface, and a lower surface, the spacer configured and dimensioned for insertion between vertebrae;   a plate secured to the second end portion of the spacer, the plate including at least one blade configured and dimensioned to penetrate adjacent vertebrae; and   an actuator for causing the at least one blade to move to penetrate adjacent vertebrae.   
     
     
         46 . The implant of  claim 45 , wherein the at least one blade is configured to rotate from a first position wherein the blade is adjacent to the plate to a second position wherein the blade is not adjacent to the plate. 
     
     
         47 . The implant of  claim 46 , wherein the blades are configured to provide compression as they are rotated into the second position. 
     
     
         48 . The implant of  claim 46 , further comprising a locking mechanism to prevent the blades from rotating back to the first position.