Dynamic spinal stabilization assemblies, tool set and method
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.
1. A bone screw assembly comprising:
a receiver having an upper portion configured to receive a rod, a cavity and a base with a lower opening defined in the base and communicating with the cavity;
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 so as 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 receiver is configured to capture the upper end portion of the shank in a seated orientation thereby restricting a hinged motion of the shank body 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 into the seated orientation and prior to the rod and a closure being positioned in the receiver.
2. The 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 bone screw assembly of claim 2 , wherein the receiver is configured to be removable from the shank in the loading orientation wherein the upper end portion of the shank is passable from the cavity to a lower exterior of the receiver.
4. The bone screw assembly of claim 1 , wherein the seated orientation comprises the upper end portion of the shank disposed at a lower portion of the cavity.
5. The bone screw assembly of claim 4 , wherein the seated orientation further comprises the upper end portion of the shank seated on a lower seating surface of the receiver at the lower portion of the cavity.
6. The bone screw assembly of claim 4 , wherein the receiver is configured to restrict the upper end portion of the shank from passing from the cavity to a lower exterior of the receiver.
7. The bone screw assembly of claim 1 , wherein the hinged motion of the shank body is restricted to the single plane with respect to a central axis of the receiver.
8. The bone screw assembly of claim 1 , wherein the receiver is configured to be removable from the upper end portion of the shank after the shank is deployed into a vertebra.