Self-holding screw head

Patent metadata

Field	Value
Publication number	US-11925399-B2
Application number	US-202217851311-A
Country	US
Kind code	B2
Filing date	Jun 28, 2022
Priority date	Jan 5, 2017
Publication date	Mar 12, 2024
Grant date	Mar 12, 2024

Abstract

A screw insertion system has a screw having a threaded shaft and a head. The head has a conically tapered outer surface, the taper increasing in distance from a central longitudinal axis of the screw from a free end of the head towards a larger diameter adjacent the connection between the head and the threaded shaft. The conically tapered head outer surface has preferably two helically extending partially rounded threads. The head has a drive element for engaging a driver. A tubular screw holder has an outer surface and internal bore extending between a leading end and a trailing end for receiving the screw. The leading end having a conically tapered inner threaded portion for engaging the conically tapered outer thread of the screw head. The tubular screw holder outer surface having a diameter less than or equal to the maximum diameter of the conically tapered head.

First claim

The invention claimed is:

1. A bone fastener comprising:
a threaded shaft extending from a leading end to a trailing end, the threaded shaft having a central longitudinal axis therethrough; and
a head extending from the trailing end of the threaded shaft, the head having a threaded surface including a helical root,
wherein the helical root continuously becomes closer to the central longitudinal axis moving away from the threaded shaft to a free end of the head.

2. The bone fastener of claim 1 , wherein the helical root extends from a first end proximal to the trailing end of the threaded shaft to a second end proximal to the free end of the head.

3. The bone fastener of claim 1 , wherein at least a portion of the helical root becomes closer to the central axis at a constant rate moving away from the threaded shaft toward the free end of the head.

4. The bone fastener of claim 1 , wherein the threaded shaft includes a tapered tip, the tapered tip being threaded.

5. The bone fastener of claim 1 , wherein the threaded shaft further comprises a threaded surface from a first location on the threaded shaft to the leading end of the threaded shaft, and a distance from the first location to the trailing end of the threaded shaft is less than a dimension of the head along the central longitudinal axis.

6. The bone fastener of claim 1 , wherein the threaded shaft further comprises a trailing portion including a circumferential concave surface abutting the head.

7. A bone fastener insertion system including:
the bone fastener of claim 1 ; and
a bone fastener holder including an internal bore configured to receive the head of the bone fastener.

8. A bone fastener comprising:
a threaded shaft extending from a leading end to a trailing end, the threaded shaft having a central longitudinal axis therethrough; and
a head extending from the trailing end of the threaded shaft, the head having a threaded surface including a crest portion having a width bounded by a first root portion of the threaded surface on a first side of the crest portion and a second root portion on a second side of the crest portion opposite the first side, a surface of the crest portion at a first circumferential location on the head tapering toward the central longitudinal axis across the width of the crest portion between the first root portion and the second root portion.

9. The bone fastener of claim 8 , wherein a linear axis is coincident with a surface extending across the width of the tapering crest portion at the first circumferential location, the linear axis and the central longitudinal axis defining a first plane.

10. The bone fastener of claim 8 , wherein the crest portion is part of a crest on the threaded surface, the crest extending from a first end of the head proximal to the trailing end of the threaded shaft to a second end of the head opposite the first end.

11. The bone fastener of claim 10 , wherein the head further comprises a circumferential surface parallel to the central longitudinal axis at the first end of the head.

12. The bone fastener of claim 10 , wherein the threaded shaft further comprises a trailing portion abutting the head, the trailing portion including a concave circumferential surface.

13. The bone fastener of claim 12 , wherein a length of the threaded shaft from the trailing end to the leading end is defined by the trailing portion and a threaded portion, the trailing portion being shorter than the head and the threaded portion being threaded throughout.

14. A bone fastener insertion system including:
the bone fastener of claim 8 ; and
a bone fastener holder including an internal bore configured to receive the head of the bone fastener.

15. A bone fastener comprising:
a shaft; and
a threaded head extending from the shaft such that a first end of the threaded head abuts the shaft and a second end of the threaded head is opposite the first end, a maximum diameter of the bone fastener being at the first end,
wherein the threaded head has a threaded outer surface extending from a first location at the first end of the threaded head to a second location proximal to the second end of the threaded head.

16. The bone fastener of claim 15 , wherein the threaded outer surface includes a crest and a root from the first location to the second location, the root having a constant rate of taper over at least part of a distance between the first location and the second location.

17. The bone fastener of claim 15 , wherein the screw has a central longitudinal axis therethrough and a diameter of the screw decreases in both opposite directions moving away from the first end of the threaded head along the central longitudinal axis.

18. The bone fastener of claim 17 , wherein the shaft further comprises a trailing portion abutting the first end of the threaded head, the trailing portion including a concave circumferential surface.

19. The bone fastener of claim 18 , wherein the shaft has a length defined by the trailing portion and a threaded portion, the trailing portion being shorter than the threaded head and the threaded portion being threaded throughout.

20. A bone fastener insertion system including:
the bone fastener of claim 15 ; and
a bone fastener holder including an internal bore configured to receive the threaded head of the bone fastener.

Assignees

• Stryker European Operations Holdings Llc

Inventors

• Zander Nils
• Wieland Manfred

Classifications

• A61B17/862 Primary

  at the periphery of the screw head · CPC title

• A61B17/8891

  at its periphery · CPC title

• A61B17/8615

  at the central region of the screw head · CPC title

• A61B17/7233 Primary

  with special means of locking the nail to the bone · CPC title

• A61B17/921

  for intramedullary devices · CPC title