Patent ID: 11957386
Assignee: nan
Field: Medical technology (Instruments)
Classification: CPC A | IPC A

Claim 0:
1. A pivotal bone anchor assembly configured to secure an elongate rod to a bone of a patient via a closure top, the pivotal bone anchor assembly comprising:
a receiver comprising a vertical centerline axis, a base defining a lower portion of a central bore communicating with a bottom surface of the receiver through a bottom opening, and a pair of opposed upstanding arms extending upward from the base to define an open channel configured to receive the elongate rod, the central bore extending upward through the open channel to tops of the upstanding arms and including a partially spherical-shaped internal surface adjacent the bottom opening, a discontinuous guide and advancement structure formed into opposed interior surfaces of the central bore adjacent the tops of the upstanding arms, and at least one horizontally extending recess located above the partially spherical-shaped internal surface and below the guide and advancement structure, the at least one horizontally extending recess having a cylindrical sidewall surface and a downwardly-facing planar upper surface;
a shank comprising a longitudinal axis, a shank body having a capture structure at an upper end configured for positioning within the central bore of the receiver, and an anchor portion at a lower end configured to attach to the bone, the capture structure including a partially spherical-shaped lower surface that extends radially outward and axially upward from the shank body and configured to slidably engage with the partially spherical-shaped internal surface of the central bore of the receiver so as to provide for pivotal motion of the shank with respect to the receiver; and
an insert comprising a body with a pair of upwardly-extending insert arms defining a rod seating surface between the insert arms configured to engage with the elongate rod, and at least one discontinuous circumferentially extending and outwardly-projecting radiused structure relative to the body having an upward-facing surface,
wherein the insert is configured to top load into the central bore of the receiver and to be downwardly displaceable until the at least one discontinuous circumferentially extending and outwardly-projecting radiused structure snaps into the at least one horizontally extending recess of the central bore, with the upward-facing surface of the at least one discontinuous circumferentially extending and outwardly-projecting radiused structure being under the downwardly-facing planar upper surface of the at least one horizontally extending recess so as to prevent upward movement of the insert within the central bore.