Polyaxial bone anchor with pop-on shank, friction fit retainer, winged insert and low profile edge lock

Abstract

A polyaxial bone screw assembly includes a threaded shank body having an integral upper portion receivable in an integral receiver, the receiver having an upper channel for receiving a longitudinal connecting member and a lower cavity cooperating with a lower opening. A down-loadable compression insert, a down-loadable friction fit split retaining ring having inner and outer tangs and an up-loadable shank upper portion cooperate to provide for pop- or snap-on assembly of the shank with the receiver either prior to or after implantation of the shank into a vertebra. The shank and receiver once assembled cannot be disassembled.

What is claimed and desired to be secured by Letters Patent is as follows: 
     
         1 . A bone anchor comprising:
 a) a shank having a body for fixation to a bone and an integral upper head;   b) a receiver having a top portion and a base and an outer surface, the receiver top portion having an open channel with a first width, the base having a chamber and a lower opening, the chamber communicating with both the channel and the lower opening; the interior of the receiver including a surface with a pair of opposed wing receiving apertures;   c) an insert disposed within the receiver, the insert having a surface sized and shaped for frictional mating cooperation with the shank head, the insert further having a pair of outwardly extending arms having a second width greater than the channel first width and each arm having a distal wing; the insert being received in the receiver in a first orientation wherein the insert is positioned such that the wings extend outward to either side of the channel; the insert is rotated ninety degrees to a second orientation such that the wings are each located in a respective wing receiving aperture so as to secure the insert in the receiver; the insert further including a pair of radially inward directed tool receiving apertures sized and shaped to be adapted to receive opposite sides of a rotation tool for effecting rotation of the insert in the receiver; and   d) a retainer operably capturing the shank within the chamber.   
     
     
         2 . The anchor of  claim 1  wherein a pair of shallow grooves and a pair of respective through apertures are formed in the outer surface of the receiver, each groove communicating with a respective aperture, each groove extending from the respective aperture to a top surface of the top portion of the receiver, each groove having a width for receiving a manipulation tool. 
     
     
         3 . The anchor of  claim 1  wherein the insert has an outer surface releasably frictionally lockable against the receiver chamber. 
     
     
         4 . The anchor of  claim 1  wherein the receiver channel is a first channel and the insert has a second channel, the insert being top loaded into the receiver and then rotated into a position above the retainer with the second channel aligned with the first channel.