Interbody fusion implant and screw guide

Abstract

An interbody fusion implant fits between adjacent vertebrae for fixation during fusion thereof. Upper bores extend into a cephalid surface of the implant and preferably include threads therein. A guide tool is removably attachable to the implant which supports guide bores along centerlines aligned with the upper bores in the implant. A drill can pass along these guide bores to form holes in a vertebra adjacent the cephalid surface of the implant which is precisely aligned with the upper bores. A hybrid screw then passes through these holes in the vertebra adjacent the cephalid surface and threads into the upper bores to secure the implant to the adjacent cephalid vertebra. Bone screws can also be used to secure the implant to caudal vertebra by passing through bores passing through the implant, such that the implant is securely mechanically fastened to both cephalid and caudal vertebrae adjacent the implant.

What is claimed is: 
     
         1 : A method for securing an implant to an adjacent structure, including the steps of:
 identifying an implant having an anterior surface and a cephalid surface opposite a caudal surface, the implant having at least one bore extending into the cephalid surface thereof along a bore centerline extending from the cephalid surface toward the caudal surface and away from the anterior surface and wherein the at least one bore extending into the cephalid surface includes female threads thereon;   identifying a hybrid screw with a proximal end opposite a distal end, said proximal end having a head with a torque applying interface thereon and the distal end having male threads thereon, the hybrid screw having a bone engaging structure on a proximal side of the male threads and spaced from the male threads for engagement of a vertebra adjacent the cephalid surface of the implant;   selecting a guide having a guide bore extending therethrough, the guide being removably attachable to the implant;   placing the implant at an implant location with an adjacent structure covering the bore into the cephalid surface;   attaching the guide to the implant with the guide bore aligned with the centerline of the bore into the cephalid surface;   cutting a hole through the adjacent structure along the centerline to the bore, using the guide bore;   placing the hybrid screw with the male threads matching the female threads in the bore through the hole in the adjacent structure formed during said cutting step with the male threads engaging the female threads; and   threading the screw into the bore in the implant until the adjacent structure is secured to the implant by the bone engagement structure.   
     
     
         2 : The method of  claim 1  wherein said screw has both the male threads and bone threads, with the male threads closer to a distal end of the screw than the bone threads, and the bone threads providing at least a portion of the bone engagement structure securing the adjacent structure to the implant as part of said threading step. 
     
     
         3 : The method of  claim 1  wherein said cutting step includes the step of drilling a hole through the adjacent structure, the hole having a diameter large enough to allow the screw to pass through the hole during said placing a screw step. 
     
     
         4 : The method of  claim 1  wherein said identifying an implant step includes said implant having at least one additional bore extending into the cephalid surface of the implant along a separate bore centerline oriented non-parallel with said bore centerline of said at least one bore, wherein said selecting a guide step includes the guide having at least one additional guide bore with the at least one additional guide bore aligned with the separate bore centerline for at least one additional bore extending into the cephalid surface of the implant, wherein said cutting step includes cutting at least one additional hole through the adjacent structure aligned with the at least one additional bore in the implant, and wherein said placing step includes placing at least one additional screw into the at least one additional hole formed in the adjacent structure during said cutting step, and threaded into the at least one additional bore in the cephalid surface of the implant. 
     
     
         5 : The method of  claim 4  wherein said identifying step includes the implant having throughbores extending from said anterior surface through said caudal surface, and at least one bone screw sized to pass through said throughbore from said anterior surface through to said caudal surface with threads on the bone screw engaging a structure adjacent the caudal surface of the implant and with the bone screw also engaging at least a portion of the implant for attachment of the implant to the structure adjacent the caudal surface of the implant.