Dynamic spinal stabilization assemblies, tool set and method

Abstract

A hinged bone screw and tool set is used for implanting such bone screws in a human spine, followed by the implantation of a longitudinal connecting member into the bone screws. The hinged bone screw includes a shank with an upper portion and a receiver with integral arms forming a U-shaped channel. A lower curved seat partially defining the U-shaped channel cooperates with an upper portion of the bone screw shank for hinged movement of the shank with respect to the receiver. The tool set includes an insertion tool, a bone screw driver, a reduction tool and a closure starter. The insertion tool includes a bone screw attachment structure and a laterally opening channel. The insertion tool further includes a threaded portion for cooperation with the reduction tool to provide synchronized placement of a closure structure in the bone screw receiver while reducing and capturing a longitudinal connecting member within the receiver. Further alternative bone screws are hinged, polyaxial or fixed and include lordosing or kyphosing lateral surfaces.

What is claimed is: 
     
         1 . A pivotal bone screw assembly comprising:
 a receiver having an upper portion configured to receive a rod, a cavity and a base with a lower opening formed in the base and communicating with the cavity; and   a shank having a body, a longitudinal axis, and an upper end portion integral with the body, the integral upper end portion includes a drive structure positioned at least partially along the longitudinal axis and configured to receive a drive tool, the shank being configured to be bottom loadable into the receiver with the upper end portion inserted through the lower opening and positionable into the cavity,   wherein upon the upper end portion of the shank being positioned into the cavity of the receiver, the assembly is configured so that the upper end portion of the shank is retained in the receiver with a pivotal motion of the body of the shank restricted to a single plane with respect to the receiver, and   wherein the receiver is configured to be removable from the upper end portion of the shank after the upper end portion of the shank is positioned in the cavity through the lower opening and retained within the cavity of the receiver and prior to the rod and a closure being positioned in the receiver.   
     
     
         2 . The pivotal bone screw assembly of  claim 1 , wherein the upper end portion of the shank is positionable in the cavity in a loading orientation with the upper end portion of the shank disposed at an upper portion of the cavity. 
     
     
         3 . The pivotal bone screw assembly of  claim 2 , wherein the receiver is configured to be removable from the shank in the loading orientation, and wherein the upper end portion of the shank is passable from the cavity to a lower exterior of the receiver. 
     
     
         4 . The pivotal bone screw assembly of  claim 1 , wherein the retained position in the receiver comprises the upper end portion of the shank disposed at a lower portion of the cavity.