Hinged anterior cervical plate system

Abstract

A folding anterior cervical locking plate system for stabilizing the cervical spine in a spinal fusion procedure. The plate system has at least two plate sections hinged together by a hinge structure at adjacent ends for pivoting movement of the plate sections relative to one another through at least 90° in each of two directions. A first hole in each plate section enables visualization of the underlying graft. A locking plate spans adjacent ends of the plate sections and holes in the locking plate are aligned with holes in adjacent plate sections so pedicle screws inserted through the holes in the locking plates extend through the holes in the plate sections to secure the system to the vertebral bodies and stabilizes the cervical spine. In one embodiment the locking plate slides in guide channels on opposite side edges of the plate sections.

What is claimed is: 
     
         1 . A folding plate system for stabilizing adjacent vertebral bodies in a cervical spine, said plate system comprising:
 at least two plate sections connected to one another via a uniaxial rotating hinge, the uniaxial rotating hinge having only a single axis of rotation which extends parallel to adjacent ends of the at least two plate sections such that the at least two plate sections are pivotable out of plane with one another about the single axis of rotation;   a peripherally enclosed visualization hole in each of the at least two plate sections arranged and disposed for visualization of an underlying graft site; and   a plurality of screw holes through each of the at least two plate sections for receiving screws inserted therethrough, each of the plurality of screw holes having a cross-sectional area less than the visualization hole.   
     
     
         2 . The folding plate system of  claim 1 , wherein the at least two plate sections are made of titanium. 
     
     
         3 . The folding plate system of  claim 1 , wherein each of the at least two plate sections measures 2-3 mm in thickness, 6-10 mm in width, and 20-30 mm in length. 
     
     
         4 . The folding plate system of  claim 1 , further including a locking plate sized to extend between the at least two plate sections, the locking plate having a plurality of holes therethrough spaced to align with at least some of the plurality of screw holes in the at least two plate sections such that screws inserted through the plurality of holes in the locking plate and the at least some of the plurality of screw holes in the at least two plate sections fix the at least two plate sections so as to resist pivoting movement of the at least two plate sections relative to one another about the single axis of rotation. 
     
     
         5 . The folding plate system of  claim 4 , wherein the locking plate extends across the uniaxial rotating hinge. 
     
     
         6 . The folding plate system of  claim 4 , further including a guide channel extending longitudinally along each of opposite side edges of each of the at least two plate sections such that the locking plate is retained and guided at opposite side edges in the guide channels for sliding movement in the guide channels from an unlocked position on top of one of the at least two plate sections to a locked position spanning the uniaxial rotating hinge connecting the at least two plate sections. 
     
     
         7 . The folding plate system of  claim 1 , wherein locking plate is made of titanium. 
     
     
         8 . The folding plate system of  claim 1 , wherein the uniaxial rotating hinge includes a pair of support arms extending from a first plate section of the at least two plate sections, a pivot pin supported by the pair of support arms, and a bore extending transversely in a second plate section of the at least two plate sections, the pin being rotatably received in the bore to pivotally connect together said the plate section and the second plate section. 
     
     
         9 . The folding plate system of  claim 8 , wherein:
 a slot extends longitudinally in the second plate section in angularly offset relation below a plane of the second plate section, said slot opening into the bore and enabling the pivot pin to be inserted endwise into the bore, the slot terminating in spaced relation to an adjacent side edge of the second plate section, wherein an end of the slot forms a stop that limits how far the pivot pin may be inserted into the bore; and   notches formed in the second plate section in spaced locations corresponding to locations of the support arms on the first plate section when the pivot pin of said first plate section is fully inserted into the bore of the second plate section, the notches extending transversely to the slot and terminating at upper and lower extremities in upper and lower surfaces, respectively, of the second plate section such that the plate sections are pivotable up and down relative to one another.   
     
     
         10 . The folding plate system of  claim 1 , wherein the at least two plate sections consist of a first plate section and a second plate section so as to form a two-level system. 
     
     
         11 . The folding plate system of  claim 1 , wherein the at least two plate section includes a first plate section and a second plate section connected to one another via the uniaxial rotating hinge and a third plate section connected to the second plate section via a second uniaxial rotating hinge so as to form a three-level system. 
     
     
         12 . The folding plate system of  claim 1 , wherein the at least two plate sections are pivotable out of plane with one another about the single axis of rotation via the uniaxial rotating hinge through at least 90° in each of two directions relative to one another. 
     
     
         13 . The folding plate system of  claim 1 , wherein at least one of the at least two plate sections includes an end opposite the uniaxial rotating hinge which is free of a hinge-forming structure. 
     
     
         14 . The folding plate system of  claim 1 , wherein the plurality of screw holes through each of the at least two plate sections includes four screw holes through each of the at least two plate sections. 
     
     
         15 . The folding plate system of  claim 14 , wherein the four screw holes are disposed adjacent to four corners of each of the at least two plate sections. 
     
     
         16 . The folding plate system of  claim 1 , wherein the visualization hole is disposed at a center of each of the at least two plate sections. 
     
     
         17 . A method for stabilizing adjacent vertebral bodies in a cervical spine, comprising:
 inserting a folding plate system through an in incision into a position adjacent to an anterior surface of the cervical spine while the folding plate system is in a folded configuration, the folding plate system including:
 at least two plate sections connected to one another via a uniaxial rotating hinge, the uniaxial rotating hinge having only a single axis of rotation which extends parallel to adjacent ends of the at least two plate sections such that the at least two plate sections are pivotable out of plane with one another about the single axis of rotation; 
 a peripherally enclosed visualization hole in each of the at least two plate sections arranged and disposed for visualization of an underlying graft site; and 
 a plurality of screw holes through each of the at least two plate sections for receiving screws inserted therethrough, each of the plurality of screw holes having a cross-sectional area less than the visualization hole, then 
   unfolding the folding plate system to a flattened configuration by rotating the at least two plate section relative to one another into a planar relationship; and   attaching the folding plate system to the adjacent vertebral bodies with a plurality of screws.   
     
     
         18 . The method of  claim 17 , further including positioning a locking plate extending between the at least two plate sections, and rotationally fixing the at least two plate sections with the locking plate so as to resist pivoting movement of the at least two plate sections relative to one another about the single axis of rotation. 
     
     
         19 . The method of  claim 18 , wherein the locking plate includes a plurality of holes therethrough spaced to align with at least some of the plurality of screw holes in the at least two plate sections, and rotationally fixing the at least two plate sections with the locking plate includes inserting screws through the plurality of holes in the locking plate and the at least some of the plurality of screw holes. 
     
     
         20 . The method of  claim 19 , wherein the locking plate is sized to extend across the uniaxial rotating hinge and the at least two locking plates include a guide channel extending longitudinally along each of opposite side edges of each of the at least two plate sections, and positioning the locking plate includes sliding the locking plate through the guide channel such that the locking plate is retained at opposite side edges in the guide channels in a locked position spanning the uniaxial rotating hinge.