Pivotal bone anchor assembly with post-positioning compression insert tool deployment

A pivotal bone anchor assembly for anchoring to patient bone, the assembly configured for deployment using a deployment tool prior to coupling with an elongated implant, the pivotal bone anchor assembly comprising:

• a shank comprising a head and a bone engagement portion extending downwardly from the head;
• a receiver comprising a body defining an internal cavity centered around a longitudinal axis, and first and second upright arms extending upward from the body to define an open channel extending transverse to the longitudinal axis and configured to receive the elongated implant, the open channel communicating with the internal cavity to define an axial bore having an internal wedging surface, the internal cavity being in communication with a bottom of the receiver through a bottom opening centered about the longitudinal axis, the receiver further including an exterior tool attachment structure for gripping engagement by the deployment tool;
• a retainer disposed within the receiver internal cavity before the shank head, the retainer having a central bore and being displaceable within the receiver internal cavity from a load position in an upper region of the internal cavity to a deployed position in a lower region of the internal cavity, the retainer being held in the load position with the central bore centered about the receiver longitudinal axis above the receiver bottom opening, and being configured to receive and retain the shank head upon an uploading of the shank head into the receiver internal cavity through the bottom opening and into the retainer central bore;
• and
• a compression insert positionable inside the receiver before the shank head, the compression insert having an upper surface engageable by the deployment tool and a bottom surface overlapping and abutting a top surface of the retainer when the retainer is in the load position,
• wherein the insert is configured for downward deployment by the deployment tool, prior to the elongated implant being secured in the receiver open channel via the closure, into an interference interface with the axial bore internal wedging surface, with the deployment tool also being in the gripping engagement with the receiver exterior tool attachment structure, and
• wherein the retainer and shank head are downwardly displaceable together into the deployed position, with the retainer being compressed between an inner surface of the receiver internal cavity and an outer surface of the shank head.

A pivotal bone anchor assembly for anchoring to patient bone for deployment using a deployment tool, and for coupling with an elongated implant via a closure, the pivotal bone anchor assembly comprising:

• a shank comprising a head and a bone engagement portion extending downwardly from the head;
• and
• a receiver subassembly having a longitudinal axis and configured to couple with the shank head, the receiver subassembly including:
• a receiver comprising a body defining an internal cavity centered around a longitudinal axis, and first and second upright arms extending upward from the body to define an open channel extending transverse to the longitudinal axis and configured to receive the elongated implant, the internal cavity being in communication with the channel and with a bottom of the receiver through a bottom opening centered about the longitudinal axis, the receiver further including an exterior tool attachment structure for gripping by the deployment tool;
• a retainer being disposed into a load position within the receiver internal cavity before the shank head, the retainer having a central bore centered about the receiver subassembly longitudinal axis and coaxial with the receiver bottom opening and being configured to capture the shank head upon an uploading of the shank head into the receiver internal cavity through the bottom opening and into the retainer central bore;
• and
• a compression insert having an upper surface engageable with the elongated implant and a bottom surface engageable with a top surface on the retainer while the retainer is maintained in an upper portion of the receiver internal cavity, the compression insert being disposed within the receiver channel before the shank head is uploaded through the receiver bottom opening and captured within the retainer,
• wherein the retainer is held in the load position with a top outer surface of the compression insert abutting an overlying surface of the receiver to inhibit an upward movement of the compression insert and the retainer during the uploading of the shank head into the retainer central bore, and
• wherein after the shank head is disposed within the retainer central bore, the compression insert is downwardly displaceable within the receiver by pressure from the deployment tool that is also in a gripping engagement with the receiver exterior tool attachment structure, until an external surface on the compression insert enters into an interference interface against an internal wedging surface of the receiver that prevents the compression insert from moving back up within the receiver and maintains the retainer in a deployed position after the deployment tool is removed from the receiver.