Pivotal bone anchor assembly with unlocked forced downwardly insert tool deployment

A pivotal bone anchor assembly intended for securing an elongate rod to a bone of a patient with tooling, the pivotal bone anchor assembly comprising:

• a bone anchor having a proximal portion with an at least partially spherical outer surface and an anchor portion extending distally from the proximal portion configured for attachment to the bone;
• a receiver comprising a base portion defining an internal cavity in communication with a bottom surface of the base portion through a bottom opening, and an upper portion with a pair of upright arms extending upwardly from the base portion to define an open channel configured to receive the elongate rod, the internal cavity having an upper expansion region and a lower locking region below the upper expansion region defined by a reduced width of the internal cavity adjacent the bottom opening, the internal cavity communicating with the open channel to define a central bore including a discontinuous closure mating structure adjacent a top of the receiver configured to mate with a closure and an inwardly-protruding circumferentially-extending interference engagement structure below the discontinuous closure mating structure;
• and
• a pressure insert positionable within the central bore of the receiver, the pressure insert comprising an upper seat surface sized and shaped for engaging the elongate rod and an exterior surface configured for overlapping engagement with an upper portion of the interference engagement structure of the receiver to inhibit downward movement of the pressure insert within the central bore when the pressure insert is in a first position,
• wherein after the proximal portion of the bone anchor is positioned within the internal cavity of the receiver and prior to the elongate rod being received in the open channel, the pivotal bone anchor assembly is configured to have the pressure insert forcibly downwardly displaced within the central bore by engagement with tooling into a second position in which the exterior surface of the pressure insert is moved at least partially through the interference engagement structure so as to inhibit the pressure insert from moving back up within the central bore to the first position, and
• wherein the pivotal bone anchor assembly with the insert in the second position is configured to have the bone anchor manually pivotally movable prior to locking the pivotal bone anchor assembly with the closure.