Multilock anterior cervical plating system

Abstract

Anatomically contoured anterior cervical plates with bone ingrowth surfaces, providing for intersegmental compressive preloading, and a rigid and locked interface to all of the bone screws, with those engaging the vertebrae deployed in highly convergent pairs. The bone screws have a tapered self-tapping leading end, an increasing root diameter with a generally constant outer diameter with a thread that is narrow and sharp throughout and an enlarged head portion capable of an interference fit to the receiving holes of the plate. Instrumentation consists of plate holders, a compression apparatus and a pilot hole forming device that interlocks with the plate. Methods for spinal compression and bone hole preparation are provided.

1 . A plate system adapted for application to the anterior human cervical spine and for contacting at least a portion of the anterior aspects of at least two cervical vertebral bodies, said plate system comprising: 
 a plate having a longitudinal axis and a length sufficient to span a disc space and overlap portions of at least two adjacent cervical vertebral bodies, said plate having a lower surface for placement against the vertebral bodies and an upper surface opposite said lower surface, said lower surface being concave along a substantial portion of the longitudinal axis of said plate;    at least two bone screw receiving holes extending through said plate from said upper surface through said lower surface, each of said bone screw receiving holes having a central longitudinal axis and being adapted to receive a bone screw to attach said plate to the cervical spine; and    a lock for preventing the inadvertent backing out of the screws from within said bone screw receiving holes, said lock having a threaded shaft member with a longitudinal axis and a cover portion adapted to cover only a portion of at least two of said bone screw receiving holes, said cover portion of said lock having a non-circular perimeter lying generally in a plane transverse to the longitudinal axis of said threaded shaft member, said threaded shaft member being adapted to engage said plate to secure said cover portion of said lock over a portion of said plate and a portion of at least two bone screw receiving holes.    
     
     
         2 . The plate system of  claim 1 , wherein said plate includes a recess configured to receive at least a portion of the perimeter of said cover portion.  
     
     
         3 . The plate system of  claim 1 , wherein at least two of said bone screw receiving holes lie along a line transverse to the longitudinal axis of said plate to overlie one of the cervical vertebral bodies.  
     
     
         4 . The plate system of  claim 1 , wherein at least a portion of said lower surface of said plate is other than smooth.  
     
     
         5 . The plate system of  claim 1 , wherein said lock is removably coupled to said plate.  
     
     
         6 . The plate system of  claim 1 , further comprising at least a third bone screw receiving hole, said cover portion of said lock being configured to cover at least three of said bone screw receiving holes.  
     
     
         7 . The plate system of  claim 6 , further comprising at least a fourth bone screw receiving hole, said cover portion of said lock being configured to cover at least four of said bone screw receiving holes.  
     
     
         8 . The plate system of  claim 1 , wherein said lock comprises of a screw.  
     
     
         9 . The plate system of  claim 1 , in combination with at least two bone screws each having a central longitudinal axis and being adapted to engage each of the at least two vertebral bodies, respectively, each of said bone screws having a leading end for insertion into the vertebral bodies and a trailing end opposite said leading end.  
     
     
         10 . The plate system of  claim 9 , comprising at least in part of a bioresorbable material.  
     
     
         11 . The plate system of  claim 1 , wherein at least a first pair of said bone screw receiving holes is transversely oriented side-by-side in said plate to overlie the anterior aspect of a cervical vertebral body, said cover portion of said lock being adapted to cover at least in part a portion of each of said transversely oriented side-by-side bone screw receiving holes.  
     
     
         12 . The plate system of  claim 1 , in combination with an interbody implant.  
     
     
         13 . The plate system of  claim 1 , in combination with a bone graft.  
     
     
         14 . The plate system of  claim 1 , in combination with a bone growth promoting material.  
     
     
         15 . The plate system of  claim 14 , wherein said bone growth promoting material is at least in part other than bone.  
     
     
         16 . The plate system of  claim 14 , wherein said bone growth promoting material is at least in part bone.  
     
     
         17 . The plate system of  claim 14 , wherein said bone growth promoting material includes at least one of bone morphogenetic protein, hydroxyapatite, and hydroxyapatite tricalcium phosphate.  
     
     
         18 . The plate system of  claim 1 , wherein at least a portion of said lower surface of said plate comprises a bone ingrowth material.  
     
     
         19 . The plate system of  claim 1 , wherein at least a portion of said lower surface of said plate includes a bone ingrowth surface.  
     
     
         20 . The plate system of  claim 1 , wherein at least a portion of one of said plate and said lock is a bioresorbable material.