Pivotal bone anchor receiver assembly with rod and retainer engaging compression insert and bottom loaded shank

A pivotal bone anchor assembly for a securing a longitudinal connecting member to a bone via a closure, the pivotal bone anchor assembly comprising:

• a receiver including a lower body and a pair of upright arms extending upward from the lower body with opposed interior surfaces defining a receiver channel for receiving the longitudinal connecting member therebetween, the interior surfaces having a discontinuous mating structure for mating with the closure and a separate downwardly-facing surface formed therein, the downwardly facing surface being located below the discontinuous mating structure, the lower body defining a cavity in communication with the receiver channel and with a bottom surface of the receiver through a bottom opening and having an internal surface;
• a shank having an upper capture portion integral with a lower anchor portion, the lower anchor portion being threaded for attachment to the bone, the upper capture portion including a lower spherical shaped segment and an upper internal recess for receiving a driving tool, the upper capture portion being configured for uploading into the receiver cavity through the bottom opening;
• a retainer disposed within the receiver cavity prior to the shank and engageable with the shank upper capture portion to capture and hold the shank upper capture portion within the receiver cavity with the lower anchor portion extending downward through the receiver bottom opening so as to allow for pivotal movement between the shank and the receiver, the retainer being positioned between the shank upper capture portion and the receiver cavity internal surface and engageable with the receiver cavity internal surface;
• and
• an insert having an upper longitudinal connecting member engaging surface disposed within the receiver channel and a lower surface engageable with an outer surface of the retainer, the insert further having an overlapping arrangement with the receiver downwardly facing surface to inhibit upward movement of the insert within the receiver after the retainer has captured the shank in the receiver cavity and prior to locking the shank and securing the longitudinal connecting member within the receiver via the closure,
• wherein the insert remains spaced apart from the shank upper capture portion when the shank is pivoted with respect to the receiver.