US Patent 11304732 Polyaxial bone screw

A bone screw assembly includes a fastener including a shaft and a head disposed on the shaft. The fastener is configured to be anchored within a subject's bone. A receiving assembly is configured to be movably mounted on the head of the fastener. The receiving assembly includes a receiver disposable around at least a portion of the head of the fastener and defining a channel for receiving a rod member therein. A retaining ring is disposed within the receiver for holding the head of the fastener in the receiver. An insert is disposed in the receiver above the retaining ring. A saddle is disposed in the receiver above the insert. The saddle defines a cradle for seating the rod member in the receiver.