Occipital fixation system and method of use

Abstract

Disclosed is a multi-axial occipito-cervical connection system that enables an occipital rod to be coupled to a cervical rod in a manner that permits multi-axial, relative movement between the two rods about a predetermined location, such as the heads of the rods. The system includes a locking mechanism that can be actuated to lock the relative positions of the rods. The rods can provide an interconnection between one or more attachments on the skull (such as an occipital attachment) and one or more attachments to the spine (such as spine screws).

1 . An orthopedic system that is adapted to rigidly affix a skull segment onto at least one cervical vertebral bone of a subject, comprising:
 a skull attachment member adapted to be attached onto a skull segment, the skull attachment member comprising:
 a body member having a top surface and a bottom surface, the body member having a borehole extending through the top and bottom surfaces, wherein the borehole is adapted to receive a bone fastener; 
 at least one side member extending from the body, wherein the side member has a top surface and a bottom surface, wherein a rod fixation assembly extends outward from the top surface of the side member; 
   the rod fixation assembly comprising:
 a saddle member that extends away from the top surface of the side member to a top surface of the saddle member, wherein the saddle member includes an outer surface and an internal aperture, wherein the internal aperture extends from the top surface of the saddle member, wherein the saddle member includes a slot extending from one side to an opposite side of the outer surface of the saddle member, wherein the slot extends from the top surface of the saddle member towards the top surface of the side member and intersects the internal aperture, wherein the slot is adapted to receive a first connecting rod, and wherein the saddle member includes a locking feature on a wall defining the internal aperture, wherein the locking feature of the saddle member cooperatively interacts with locking features of a locking nut; 
 the locking nut having a cylindrical configuration with a top surface, a bottom surface and an outer wall, wherein the outer wall includes locking features adapted to cooperatively interact with the locking feature of the wall defining the internal aperture, and wherein the diameter of the locking nut is less than the diameter of the saddle member; 
 wherein advancement of the locking nut within the internal aperture of the saddle member rigidly affixes the first connecting rod to the saddle member; 
   a spine attachment device that is adapted to be attached onto a segment of the cervical spine;   a first connecting rod having a first segment and a second segment, wherein the first segment is adapted to be seated within the slot of the saddle member, and wherein the second segment is adapted to couple to an interconnecting member;   a second connecting rod having a first segment and a second segment, wherein the first segment is adapted to be couple with the spine attachment device, and wherein the second segment is adapted to couple to the interconnecting member;   the interconnecting member adapted to couple with the second segment of each of the first and the second connecting rod, wherein the interconnecting member includes a locking feature that is adapted to reversibly transition from a first state, wherein the second segment of the first connecting rod is movable relative to second segment of the second connecting rod, to a second state, wherein the second segment of the first connecting rod is rigidly affixed to the second segment of the second connecting rod.   
     
     
         2 . An orthopedic system as in  claim 1 , wherein a bore hole extends through the top and bottom surfaces of the side member, and wherein the borehole is adapted to receive a bone fastener. 
     
     
         3 . An orthopedic system as in  claim 2 , wherein the bore hole is positioned between the rod fixation assembly and the body member. 
     
     
         4 . An orthopedic system as in  claim 1 , wherein the locking features on the wall defining the internal aperture of the saddle member are threads. 
     
     
         5 . An orthopedic system as in  claim 4 , wherein the threads have a square thread configuration. 
     
     
         6 . An orthopedic system as in  claim 1 , wherein the locking features on the outer wall of the locking member are threads. 
     
     
         7 . An orthopedic system as in  claim 6 , wherein the threads have a square thread configuration. 
     
     
         8 . An orthopedic system as in  claim 1 , wherein the bone fastener that is inserted through the borehole of the body member is a screw. 
     
     
         9 . An orthopedic system as in  claim 8 , wherein the screw that is inserted through a borehole of the body member defines an insertion trajectory that is non-perpendicular to the underlying skull bone surface. 
     
     
         10 . An orthopedic system as in  claim 1 , wherein the body member further contains a locking mechanism that is adapted to lock the traversing bone fastener to its borehole. 
     
     
         11 . A method for the immobilization of a skull segment relative to a cervical spine segment of a human or animal subject, comprising:
 attaching a skull attachment device of an orthopedic kit rigidly onto a skull segment using at least one bone fastener, the skull attachment device comprising:
 a) a body member having a top surface and a bottom surface, the body having a borehole extending through the top and bottom surfaces, wherein the borehole is adapted to receive a bone fastener; 
 b) a side member extending from the body, wherein the side member has a top surface and a bottom surface, wherein at least one rod fixation assembly extends away from the top surface of the side member; 
 c) The rod fixation assembly being comprised of:
 a saddle member that extends away from the top surface of the side member to a top surface of the saddle member, wherein the saddle member includes an outer surface and an internal aperture, wherein the internal aperture extends from the top surface of the saddle member, wherein the saddle member includes a slot extending from one side to an opposite side of the outer surface of the saddle member, wherein the slot extends from the top surface of the saddle member towards the top surface of the side member and intersects the internal aperture, wherein the slot is adapted to receive a first connecting rod, and wherein the saddle member includes a locking feature on a wall defining the internal aperture, wherein the locking feature of the saddle member cooperatively interacts with locking features of a locking nut; 
 the locking nut having a cylindrical configuration with a top surface, a bottom surface and an outer wall, wherein the outer wall includes locking features adapted to cooperatively interact with the locking feature of the wall defining the internal aperture, and wherein the diameter of the locking nut is less than the diameter of the saddle member; 
 wherein advancement of the locking nut within the internal aperture of the saddle member rigidly affixes the first connecting rod to the saddle member; 
 
   attaching a spine attachment device onto at least a segment of the cervical spine;   positioning an interconnecting assembly between the skull attachment device and the spine attachment device, wherein the interconnecting assembly includes at least a first rod member, a second rod member and an interconnecting fastener, wherein each of the first and second rod members contain a second segment, wherein the second segment of each rod member is adapted to couple with the interconnecting fastener, and wherein the interconnecting fastener contains a locking feature that is adapted to reversibly transition from a first state, wherein the second segment of the first rod member is movable relative to second segment of the second rod member, to a second state, wherein the second segment of the first rod member is rigidly affixed to the second segment of the second rod member;   coupling the first segment of the first rod member with the saddle member of the skull attachment device and coupling the first segment of the second rod member with the spine attachment device;   rigidly immobilizing the first rod member relative to the skull attachment device and the second rod member relative to spine attachment device;   transitioning the interconnecting fastener into the second state and rigidly immobilizing the second segment of the first rod member to the second segment of the second rod member.   
     
     
         12 . A method as in  claim 11 , wherein the skull and cervical spine segments are positioned into a desired spatial relationship prior to rigidly immobilizing the skull attachment member and the spine attachment device. 
     
     
         13 . A method as in  claim 11 , wherein a bore hole extends through the top and bottom surfaces of the side member, and wherein the borehole is adapted to receive a bone fastener. 
     
     
         14 . A method as in  claim 13 , wherein the bore hole is positioned between the rod fixation assembly and the body member. 
     
     
         15 . A method as in  claim 14 , wherein the locking features on the wall of the internal aperture of the saddle member are threads. 
     
     
         16 . A method as in  claim 15 , wherein the threads have a square thread configuration. 
     
     
         17 . A method as in  claim 11 , wherein the locking features on the outer wall of the locking member are threads. 
     
     
         18 . A method as in  claim 17 , wherein the threads have a square thread configuration. 
     
     
         19 . A method as in  claim 11 , wherein the bone fastener that is inserted through the borehole of the body member is a screw. 
     
     
         20 . A method as in  claim 19 , wherein the screw that is inserted through a borehole of the body member defines an insertion trajectory that is non-perpendicular to the underlying skull bone surface. 
     
     
         21 . A method as in  claim 11 , wherein the body member further contains a locking mechanism that is adapted to lock the traversing bone fastener to its borehole. 
     
     
         22 . An orthopedic system as in  claim 11 , wherein the saddle member is movable relative to the side member. 
     
     
         23 . An orthopedic system as in  claim 22 , wherein advancement of the locking member within the internal aperture of the saddle member rigidly affixes the saddle member to the skull attachment member.