# US 2018/0021067 A1 · Cannulated polyaxial screw > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0021067 A1 - Document ID: US20180021067A1 - Status: Published application - Kind: A1 - Application number: 15/723,972 - Filed: 2017-10-03 - Published: 2018-01-25 - Earliest claimed: 2003-06-18 - Inventors: Roger P. Jackson - Web page: https://patentgrep.com/patent/US20180021067A1 ## CPC - A61B 17/7037: {wherein pivoting is blocked when the rod is clamped} - A61B 17/7032: {Screws or hooks with U-shaped head or back through which longitudinal rods pass} - A61B 17/86: Pins or screws {or threaded wires; nuts therefor (A61B17/72 take precedence)} - A61B 2560/0406: specially shaped apparatus housings - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) ## Abstract A polyaxial bone screw having a bone implantable shank, a head and a retaining ring. The retaining ring includes an outer partial hemispherical surface and an inner bore with radially extending channels and partial capture recesses. The shank includes a bone implantable body with an external helical wound thread and an upwardly extending capture structure. The capture structure includes at least one spline which extends radially outward and has a wedged surface that faces radially outward therefrom. The capture structure operably passes through a central bore of the retaining ring while the spline passes through a suitably shaped channel so that the spline becomes positioned above the head at which time the shank is rotated appropriately and the shank is drawn back downwardly so that the spline engages and seats in the capture recess. The head includes an internal cavity having a spherical shaped surface that mates with the ring surface and has a lower restrictive neck that prevents passage of the ring once the ring is seated in the cavity. ## Claims ### Claim 1 A pivotal bone screw assembly for securing a longitudinal stabilization member to a bone, the pivotal bone screw assembly comprising: a head member having a base defining a cavity with a bottom opening in communication with a bottom surface of the base, and a pair of integral arms extending upward from the base to define a channel in communication with the cavity and having interior surfaces for receiving the longitudinal stabilization member therebetween, the cavity having an internal surface that narrows toward the bottom opening; an anchor member having a proximal end portion, a distal end portion, and a central opening extending entirely through the anchor member along a central longitudinal axis of the anchor member and opening onto a top end of the proximal end portion and a bottom end of the distal end portion, the central opening being closed laterally along an entire length thereof and having a constant diameter at least along the distal end portion of the anchor member and including the bottom end opening, the distal end portion comprising an implant portion to be implanted into the bone; and a retainer disposed within the cavity prior to the anchor member, the retainer having an outer surface operable to engage the cavity internal surface, and a central bore with an inner surface operable to engage the proximal end portion of the anchor member, wherein the retainer secures the proximal end portion of the anchor member in spaced relation to the cavity internal surface while allowing for pivotal motion of the anchor member relative to the head member. ### Claim 2 (depends on 1) The pivotal bone screw assembly of claim 1, wherein the retainer outer surface further comprises an outer partial hemispherical shaped surface that allows the retainer to pivot with respect to the head member when the bone screw assembly is in an unlocked configuration. ### Claim 3 (depends on 1) The pivotal bone screw assembly of claim 1, wherein the cavity further comprises a partial hemispherical internal seating surface. ### Claim 4 (depends on 1) The pivotal bone screw assembly of claim 1, wherein the top end of the proximal end portion extends above a top surface of the retainer. ### Claim 5 (depends on 4) The pivotal bone screw assembly of claim 4, wherein the top end of the proximal end portion further comprises a radiused upper surface with the central opening exiting therethrough. ### Claim 6 (depends on 4) The pivotal bone screw assembly of claim 4, wherein the top end of the proximal end portion engages with an underside surface of the longitudinal stabilization member when the bone screw assembly is in a locked configuration. ### Claim 7 (depends on 1) The pivotal bone screw assembly of claim 1, wherein the anchor member proximal end portion includes an external drive extension. ### Claim 8 (depends on 1) The pivotal bone screw assembly of claim 1, wherein the central opening is unthreaded along at least the distal end portion. ### Claim 9 (depends on 1) The pivotal bone screw assembly of claim 1, wherein distal end portion of the anchor member further comprises an implant portion with an external helically wound thread to be implanted into the bone. ### Claim 10 (depends on 9) The pivotal bone screw assembly of claim 9, wherein the anchor member further comprises a threaded shank. ### Claim 11 (depends on 1) The pivotal bone screw assembly of claim 1, wherein the retainer further comprises a continuous ring. ### Claim 12 (depends on 1) The pivotal bone screw assembly of claim 1, wherein the retainer further comprises a through-and-through gap extending from the outer surface to the inner surface and from a top to a bottom surface thereof. ### Claim 13 (depends on 1) The pivotal bone screw assembly of claim 1, further comprising a closure component to cooperate with the channel to retain the longitudinal stabilization member within the channel. ### Claim 14 (depends on 13) The pivotal bone screw assembly of claim 13, wherein the closure component further comprises a closure top to engage the channel interior surfaces to urge the longitudinal stabilization member against a radiused upper surface of the proximal end portion to lock the anchor member at a fixed angular orientation relative to the head member.