Patent ID: 8308782

Claim:
A polyaxial bone screw assembly comprising: a) a shank having an elongate body and an upper portion, the body being configured for fixation to a bone; b) a receiver having a top portion and a base, the receiver top portion defining a channel to receive a longitudinal connecting member, the base having an internal seating surface partially defining a cavity, the channel communicating with the cavity, the cavity communicating with an exterior of the base through an opening sized and shaped to upwardly load the shank upper portion through the opening; c) a retainer having at least two discrete parts, each part having an inner surface and an outer surface, the inner surface configured to be engagement with the shank upper portion and the outer surface configured to be in engagement with the receiver seating surface when the retainer is captured between the shank upper portion and the seating surface, the discrete parts cooperating to prevent the shank upper portion from passing down through the receiver opening, and wherein the parts can move with the shank in polyaxial rotation with respect to the receiver; d) a compression insert disposed within the receiver and configured to frictionally engage the shank upper portion at a location spaced from the retainer; and e) a closure structure directly engaging the compression insert, the closure structure placing a downward force on the compression insert, the compression insert placing a downward force on the shank upper portion to lock the shank with respect to the receiver.