Patent ID: 7513905
Filing Date: 2009-04-07
Classification: A61B,Y10T

Abstract:
1. A polyaxial bone screw assembly comprising: (a) a shank having a body for fixation to a bone and a capture structure extending from the body, the capture structure having an outer surface with a first helically wound guide and advancement structure and a smooth surface disposed between the first guide and advancement structure and the body; (b) a head having a top portion and a base, the head top portion defining an open channel adapted to receive a rod implant, the base having a seating surface partially defining a cavity, the channel communicating with the cavity, the cavity communicating with an exterior of the base through an opening sized and shaped to receive the capture structure therethrough; and (c) a retaining ring having an external surface and an internal surface defining a central bore configured to slidably mate with the smooth surface of the capture structure, the retaining ring external surface configured to be in slidable mating engagement with the seating surface of the head so as to enable selective angular positioning of the shank body with respect to the head; and (d) a fastener having an internal surface with a second helically wound guide and advancement structure thereon, the first helically wound guide and advancement structure configured to rotatably mate with the second helically wound guide and advancement structure to secure the fastener and the retaining ring to the capture structure within the head cavity, the fastener having structure thereon adapted to mate with a tool for operably implanting the shank in a bone of a patient, when the shank, retainer ring, fastener and head are assembled, the shank capture structure extending into the channel so as to engage a rod placed in the channel under pressure and thereby lock the shank in a desired angular configuration with respect to the head.