Polyaxial bone screw with shank articulation pressure insert and method

摘要

A polyaxial bone screw assembly includes a threaded shank body having an upper portion, a receiver member or head, a retaining and articulating structure, and a pressure insert disposed between the shank upper portion and a rod. The receiver has a U-shaped cradle defining a channel for receiving a spinal fixation rod and a receiver cavity. The retaining and articulating structure attaches to the shank and rotates with the shank in the cavity during positioning. The pressure insert presses upon the shank upper portion and not the retaining and articulating structure.

主权项

1. A bone anchor assembly comprising:
a receiver, the receiver having a top side surface, a front side surface and a back side surface and includes a first pair of upwardly extending arms forming a channel therebetween and mateable with a closure to securely lock a bone anchor with respect to a rod positionable within the channel of the receiver, wherein: each upwardly extending arm having an outward facing horizontal elongated radiused groove about a circumference of the receiver extending to at least one of the front side surface and the back side surface and located a distance from the top side surface, wherein the distance remains constant along a horizontal length of the groove, the grooves of each upwardly extending arm opposed in parallel relation to each other, and wherein the closure is positioned inwardly in the receiver with respect to the grooves and only engages the rod and the receiver.