Method of assembling a pivotable bone anchor assembly with independent locking by insert side compressing member

Abstract

A method of assembling a pivotal bone anchor assembly includes positioning a capture portion of a bone anchor and an insert within a central bore of a receiver, with the receiver having upstanding arms defining an open channel for receiving a rod, a cavity for receiving the bone anchor, and with at least one upstanding arm configured to slidably receive an insert compressing member in a direction parallel with a longitudinal axis of the receiver. The method also includes pressing continuously downward on the insert with the insert compressing member until the insert contacts the capture portion of the bone anchor to establish a pressable and releasable locking engagement of the bone anchor with respect to the receiver that is independent of a closure top. The method further includes positioning the elongate rod within the open channel of the receiver, followed by securing the closure top to a guide and advancement structure of the receiver above the elongate rod to establish a final locked configuration of the elongate rod and the pivotal bone anchor assembly, followed by slidably removing the insert compressing member from the receiver.