Patent ID: 11730526

Abstract:
A pivotal bone anchor assembly includes a bone anchor having a capture portion with a frusto-conical outer surface and a horizontal capture recess extending circumferentially around a mid-portion thereof, a receiver having a central bore with a seating surface proximate a bottom opening, and a ring retainer having a retainer aperture with an inner surface that is slidably engageable with the frusto-conical outer surface of the capture structure and a retainer aperture recess extending circumferentially into the inner surface. The assembly further includes a snap ring positionable within the retainer aperture recess with a snap ring aperture smaller than the retainer aperture. Upon securing the ring retainer within the central bore with the retainer aperture centered above the bottom opening, the capture portion is uploadable into the retainer aperture with the frusto-conical outer surface engaging and continuously expanding the snap ring until the horizontal capture recess reaches the retainer aperture recess and the snap ring snaps into the horizontal capture recess to couple the bone anchor to the ring retainer.