Spinal fixation system

Abstract

A fastener assembly for a spinal fixation system that is particularly useful in treatment of pediatric and small-statured patients includes a fastener, an attachment member, and a locking member. The fastener has a lower portion for contacting a bone and an upper portion integral with the lower portion. The upper portion has two open channels. Each channel is configured and dimensioned to receive a portion of a longitudinal or connecting member along its circumference. The attachment member is positionable on the fastener and at least partially covers the channel that receives the longitudinal or connecting member. The locking member is operatively associated with the upper portion of the fastener and secures the attachment member and the longitudinal or connecting member to the fastener.

1 . A connector for securing a longitudinal member to a fastener assembly of a spinal fixation system comprising: 
 a shaft having a longitudinal axis and first and second ends,    the first end having a hook with inner and outer surfaces, the inner surface having a concave shape, the hook having an opening opposite the inner surface to receive the longitudinal member, the hook being configured to secure the longitudinal member to the inner surface while maintaining the opening, and    the second end having a circumference and ridges around the circumference for engaging the fastener assembly, wherein the ridges are configured and dimensioned to interlock with a portion of the fastener assembly to prevent rotation of the shaft relative to the fastener assembly.    
     
     
         2 . The connector of  claim 1  wherein the hook has a bore extending from the outer surface to the inner surface, the bore configured and dimensioned to receive a set screw for pinning the longitudinal member to the inner surface of the hook.  
     
     
         3 . The connector of  claim 2  wherein the bore extends from the outer surface to the inner surface perpendicularly to the longitudinal axis of the shaft.  
     
     
         4 . The connector of  claim 1  wherein the ridges extend only partially around the circumference of the second end.  
     
     
         5 . The connector of  claim 4  wherein the opening of the bore at the outer surface and the ridges extend parallel to the longitudinal axis of the shaft.  
     
     
         6 . A spinal fixation system comprising: 
 the connector of  claim 1;  and    a fastener assembly comprising a main body, the main body having a channel dimensioned and configured to receive a portion of the second end of the connector, the main body also having either a distal threaded portion or a distal hook portion for engaging bone.    
     
     
         7 . The spinal fixation system of  claim 6  wherein the main body has a bore extending there through orthogonal to the channel.  
     
     
         8 . The spinal fixation system of  claim 6  further comprising a longitudinal member secured to the connector.  
     
     
         9 . The spinal fixation system of  claim 6  wherein the fastener assembly further comprises an attachment member that engages a proximal portion of the main body to secure the connector in the channel of the main body.  
     
     
         10 . The spinal fixation system of  claim 9  wherein the attachment member comprises serrations that interlock with the ridges of the connector to prevent rotation of the shaft with respect to the attachment member.  
     
     
         11 . The spinal fixation system of  claim 9  wherein the attachment member covers the channel only partially.  
     
     
         12 . The spinal fixation system of  claim 9  wherein: 
 the hook of the connector has a bore extending from the outer surface to the inner surface perpendicularly to the longitudinal axis of the shaft, the bore configured and dimensioned to receive a set screw for pinning the longitudinal member to the inner surface of the hook; and    the attachment member engages the proximal portion of the main body in a direction perpendicular to the longitudinal axis of the shaft.    
     
     
         13 . The spinal fixation system of  claim 6  wherein the main body of the fastener assembly further comprises a second channel dimensioned and configured to receive a portion of the second end of the connector or a longitudinal member.  
     
     
         14 . The spinal fixation system of  claim 13  wherein the two channels extend parallel to each other.  
     
     
         15 . The spinal fixation system of  claim 13  wherein the fastener assembly has a longitudinal axis extending from a proximal end to a distal end and lying in a central plane, the two channels disposed on opposite sides of the central plane.  
     
     
         16 . The spinal fixation system of  claim 15  wherein the two channels extend orthogonally with respect to the longitudinal axis of the fastener assembly and are equidistant from the proximal end of the fastener assembly.  
     
     
         17 . The spinal fixation system of  claim 13  wherein the attachment member comprises: 
 a cylinder having upper, lower, and side surfaces with a bore extending through the upper and lower surfaces, the cylinder defining a longitudinal axis lying in a central plane;    a slot extending through the cylinder offset from and parallel to the central plane of the cylinder; and    a protrusion extending from the lower surface on an opposite side of the central plane of the cylinder from the slot.    
     
     
         18 . The spinal fixation system of  claim 17  wherein the slot includes serrations along the side surface.  
     
     
         19 . The spinal fixation system of  claim 17  wherein the slot has an eccentric cross-sectional shape.  
     
     
         20 . The spinal fixation system of  claim 17  wherein the slot has a generally cylindrical cross-section with a geometry substantially conforming to a diameter of the shaft of the connector.