Closure for open-headed medical implant

Patent metadata

Field	Value
Publication number	US-9907577-B2
Application number	US-201615144915-A
Country	US
Kind code	B2
Filing date	May 3, 2016
Priority date	Dec 8, 2000
Publication date	Mar 6, 2018
Grant date	Mar 6, 2018

Abstract

A closure for an open headed medical implant, such as a bone screw. The closure having a cylindrical body having an axis of rotation and also having a radially outer surface with a thread or other guide and advancement structure thereon. The body having a plurality of apertures that open onto a top surface of the body and that are parallel to but spaced from the axis of rotation. The closure also has a break-off head centrally attached by a neck to the top surface of the body.

First claim

What is claimed and desired to be secured by Letters Patent is as follows:

1. A multi-part threaded closure plug for operably closing, with the use of a tool, a top portion of a channel between a set of arms of a bone anchor, the channel configured to receive a rod, the set of arms having top surfaces defining a top of the bone anchor and internal mating helically wound radial splay preventing threads extending downward from the top surfaces to at least partially define an axial bore of the bone anchor, the threads being configured to pull the arms toward one another when engaged with the plug, and the bone anchor axial bore having an outer circumference with a diameter partially interrupted and transected by the channel, the multi-part threaded closure plug comprising:
a body including a closed ring having an outer surface with helically wound radial splay preventing threads, the body further including a threaded central bore extending between a top surface and a bottom surface of the body about a central axis, a plurality of spaced-apart tool mating structures formed within the top surface of the body and extending partially down into the body, the plurality of spaced-apart tool mating structures configured to receive the tool to threadably advance and tighten down the body between the set of arms as the helically wound radial splay preventing threads of the outer surface engage the internal mating helically wound radial splay preventing threads of the set of arms in a threaded splay preventing mating relationship; and
a set screw having an outer surface with continuous radial threads, the set screw including a lower portion that is closed off by a continuous bottom surface, the continuous bottom surface configured to engage and lock the rod within the channel as the continuous radial threads of the outer surface of the set screw engage the threaded central bore of the body, such that each part of the multi-part threaded closure plug is positionable entirely within a perimeter of the bone anchor axial bore outer circumference in a locked position.

2. The multi-part threaded closure plug of claim 1 , wherein the set screw includes a second tool mating structure for receiving a second tool.

3. The multi-part threaded closure plug of claim 2 , wherein the set screw is threadably secured within the body threaded central bore with the second tool after the body is threadably secured within bone anchor axial bore with the first tool.

4. The multi-part threaded closure plug of claim 1 , wherein the arm top surfaces of the anchor body remain uncovered when the set screw continuous bottom surface engages and locks the rod within the channel.

5. The multi-part threaded closure plug of claim 1 , wherein the plurality of spaced-apart tool mating structures each include a square shaped opening onto the top surface of the body.

6. The multi-part threaded closure plug of claim 1 , wherein a top surface of the set screw does not extend above the bone anchor arm top surfaces after the set screw engages the rod within the channel in the locked position.

7. The multi-part threaded closure plug of claim 6 , wherein the set screw further comprises a break-off head.

8. The multi-part threaded closure plug of claim 1 , wherein the plurality of spaced-apart tool mating structures are spaced from the central axis and the outer surface of the body.

9. The multi-part threaded closure plug of claim 1 , wherein the continuous bottom surface of the set screw is substantially flat across the width thereof.

10. The multi-part threaded closure plug of claim 1 , wherein the plurality of spaced-apart tool mating structures includes at least three tool mating structures.

11. The multi-part threaded closure plug of claim 1 , wherein the continuous bottom surface of the set screw has an outer thread diameter less than a diameter of the rod.

12. A medical implant for securing a rod to a bone, the medical implant comprising:
a bone anchor head including a channel formed between a set of upright arms, the upright arms having top surfaces and internal splay preventing threads extending downward from the top surfaces to at least partially define a discontinuous threaded axial bore having a circumference that is partially interrupted and transversely transected by the channel, the channel configured to receive the rod in a lower portion thereof, the channel having an upper portion including the internal splay preventing threads;
and
a multi-part closure for closing the upper portion of the channel, each part of the multi-part closure threadably positionable entirely within the circumference of the threaded axial bore in a locked position, the multi-part closure having external splay preventing threads engageable to the internal splay preventing threads of the set of upright arms in a threaded splay preventing mating relationship that includes pulling of the arms toward one another, wherein the multi-part closure includes a body and a set screw, the body comprising a closed ring with an outer radial surface having the external splay preventing threads formed therein, a threaded central bore configured to receive the set screw, and a top surface oppose a bottom surface.

13. The medical implant of claim 12 , wherein the multi-part closure includes two parts.

14. The medical implant of claim 12 , wherein the body includes a plurality of tool mating apertures formed in the top surface and spaced apart from each other.

15. The medical implant of claim 14 , wherein the plurality of tool mating apertures further comprises four tool mating openings.

16. The medical implant of claim 14 , wherein the plurality of tool mating apertures have a square shape.

17. The medical implant of claim 12 , wherein the set screw includes a closed lower portion having a continuous and substantially flat bottom surface across a width thereof.

18. The medical implant of claim 12 , wherein the body is inserted and advanced between the set of arms prior to the set screw being advanced in the body.

19. The medical implant of claim 12 , wherein the body is inserted and advanced between the set of arms without the set screw in place.

20. The medical implant of claim 12 , wherein the multi-part closure has a low profile compared to the top surfaces of the upright arms.

21. The medical implant of claim 12 , wherein the top surfaces of the upright arms remain uncovered when the rod is secured within the bone anchor head channel by the multi-part closure locked position.

22. A threaded splay preventing closure for operably closing, with the use of a tool, a top portion of a channel between a set of arms of a bone anchor, the channel configured to receive a rod, each of the arms having a threaded splay preventing internal surface, the threaded splay preventing closure comprising:
a body comprising a closed ring with a threaded splay preventing radial outer surface, a top surface, a bottom surface, a central bore that is threaded and extends between the top surface and the bottom surface about a central axis, and a plurality of equally spaced-apart tool mating structures formed within the top surface and extending partially down into the body configured to receive the tool to threadingly advance the body between the set of arms of the bone anchor as the threaded splay preventing radial outer surface of the body threadably engages the threaded splay preventing internal surface of each of the set of arms in a threaded mating relationship, the threaded mating relationship in

Assignees

• Jackson Roger P

Inventors

• Jackson Roger P

Classifications

• A61B17/7091

  for applying, tightening or removing longitudinal element-to-bone anchor locking elements, e.g. caps, set screws, nuts or wedges · CPC title

• A61B17/685

  Elements to be fitted on the end of screws or wires, e.g. protective caps · CPC title

• A61B2090/037

  with a frangible part, e.g. by reduced diameter · CPC title

• A61B17/7082

  for driving, i.e. rotating, screws or screw parts specially adapted for spinal fixation, e.g. for driving polyaxial or tulip-headed screws · CPC title

• A61B17/7032 Primary

  Screws or hooks with U-shaped head or back through which longitudinal rods pass · CPC title