Pivotal bone anchor assembly with independent locking by a tool engaging an insert

A pivotal receiver assembly configured for independent locking, via an insert compressing tool, to a head of a bone anchor having an anchor portion implantable into a bone of a patient, prior to securing an elongate rod to the receiver assembly and the patient bone anchor via a closure top, the pivotal receiver assembly comprising:

• a receiver having a longitudinal axis, a base, and a pair of upstanding arms extending upwardly from the base with opposed inner surfaces defining an open channel configured for receiving the elongate rod, the inner surfaces of the upstanding arms having a closure top mating feature formed thereon, the base including a central opening in communication with a bottom surface of the base through a bottom opening and with the open channel to define a through-and-through aperture centered about the longitudinal axis, the upstanding arms configured to slidably receive the insert compression tool in a direction parallel with the longitudinal axis, the receiever configured to receive the head of the bone anchor in the base with the bone anchor extending downward through the receiver bottom opening and the receiver being pivotally movable with respect to the bone anchor;
• and
• an insert configured to be disposed at least partially within the receiver and thereafter configured to be downwardly compressed by the insert compression tool until the insert comes into a compressive contact with a spherical outer surface of the head of the bone anchor so as to independently lock a position of the receiver with respect to the bone anchor,
• wherein with the insert compressing tool in a downward compression position, the elongate rod is receivable within the open channel of the receiver and lockable with the closure top to establish a locked configuration, and
• wherein with the closure top maintaining the elongate rod and pivotal bone anchor assembly together in the locked configuration, the insert compressing tool is slidably removable from the receiver in a direction parallel with the longitudinal axis.