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 receiver comprising a lower body defining a cavity communicating with bottom surface of the receiver through a bottom opening and a pair of upright arms extending upwardly from the lower body with opposed inwardly facing surfaces defining an open first channel configured to receive the elongate rod and having a closure-mating structure formed therein, the open first channel communicating with the cavity to define a central bore, the central bore including upper and lower receiver abutment structures extending at least partially circumferentially around the central bore and spaced between a shank head retaining region adjacent to the bottom opening and the closure-mating structure;
- a compression insert configured for positioning in the central bore of the receiver, the compression insert comprising a central tool receiving opening, an upwardly-facing surface sized and shaped to receive the elongate rod, and exterior upper and lower insert abutment structures configured to have simultaneously overlapping arrangements with the upper and lower receiver abutment structures, respectively, when the compression insert is positioned in a first position in the central bore, so as to inhibit upward and downward movement of the compression insert within the central bore of the receiver until acted on by the tooling;
- a shank comprising a shank head and a bone anchoring portion opposite the shank head configured to attach to the bone, the shank head having a partial spherical shape defining a hemisphere plane and an internal drive socket having a multi-faceted inner surface, the shank head configured for positioning within the cavity of the receiver with the shank extending downward through the bottom opening and being initially pivotable with respect to the receiver;
- and
- a closure top configured for positioning entirely within the central bore of the receiver above the compression insert and in engagement with the closure-mating structure to apply a downward pressure toward the compression insert and the shank head of the shank until an angular orientation of the shank relative to the receiver is locked with the closure top,
- wherein after the shank head is captured within the shank head retaining region and prior to locking with the closure top, the compression insert is configured for forcible downward displacement within the receiver by direct engagement with the tooling to push the insert into a second position where at least one of the upper and lower insert abutment structures is configured to abut or engage with at least one of upper and lower receiver abutment structures so as to inhibit the compression insert from moving back up within the central bore of the receiver into the first position, and
- wherein after the forcible downward displacement of the compression insert within the central bore, the shank is configured to remain pivotable with respect to the receiver until the angular orientation of the shank relative to the receiver is locked with the closure top.