Patent ID: 11246627

Abstract:
A pivotal bone screw assembly includes a shank with a capture portion having a spherical lower surface and a body having an anchor portion for fixation to patient bone, and a head member with a channel at a proximal end for receiving a rod and a central opening extending upwardly from a distal aperture through the channel to a top of the head member. The central opening further includes a proximal portion having partial cylindrical sidewalls with a first diameter and a mating structure formed therein for mating with a closure, a distal portion having a curvate surface having an inner edge defining the distal aperture with a second diameter less than the first diameter and for pivotably engaging the spherical lower surface of the capture portion, and a central portion between the curvate surface and the mating structure with a third diameter greater than the first and second diameters. At least a partial thread is formed into the distal aperture to provide for assembly of the shank into the head member.