Patent ID: 8377102

Claim:
A polyaxial bone anchor comprising: a) a shank having a body for fixation to a bone and an integral upper portion, the upper portion having an upper end surface and at least one laterally directed projection; b) a receiver having a top portion and a base, the receiver top portion defining an open channel, the base having a seating surface partially defining a cavity, the channel communicating with the cavity, the cavity communicating with an external of the base through an opening sized and shaped to receive the shank upper portion therethrough; c) a compression insert disposed in the receiver, the insert having a lower mating surface that exclusively engages and applies downward pressure to the upper end surface of the shank upper portion; and d) a retainer having an external surface and a central bore with an internal surface defining the central bore having at least one substantially vertical channel for slideably receiving the projection therethrough and at least one pocket for downwardly receiving and holding the projection of the shank upper portion, the shank upper portion and the retainer being in fixed relation to one another, both the upper portion and the retainer being in swivelable relation within the receiver, providing selective angular positioning of the shank with respect to the receiver, the retainer external surface being in slidable engagement with the receiver seating surface during positioning, the retainer being spaced from the compression insert at any and all angular positions of the shank with respect to the receiver.