Variable angle bone fixation device

Patent metadata

Field	Value
Publication number	US-9277947-B2
Application number	US-201514662895-A
Country	US
Kind code	B2
Filing date	Mar 19, 2015
Priority date	Jun 27, 2012
Publication date	Mar 8, 2016
Grant date	Mar 8, 2016

Abstract

A bone fixation element includes a threaded head and a shaft extending along a longitudinal axis from a proximal end to a distal end, an outer surface of the head being one of carburized and nitrided and including a first groove extending into an outer surface of the head along a path interrupting the threading and extending along an angle counter to an angle of the threading.

First claim

What is claimed is:

1. A system for bone fixation, comprising:
a bone fixation plate defining a first surface configured to contact bone in an operative configuration and a second surface opposite the first surface, the bone fixation plate defining an opening that extends therethrough from the first surface to the second surface, the bone fixation plate having a first hardness; and
an elongated bone implant having a shaft configured for insertion through the opening of the bone fixation plate and into a bone, an outer surface of the bone implant being one of carburized and nitrided to have a second hardness that is greater than the first hardness,
wherein the first and second hardness are selected so that a difference therebetween increases a strength of an interface between the bone implant and the bone fixation plate and avoids burring of the bone implant when the bone implant is inserted through the opening of the bone fixation plate.

2. The system of claim 1 , wherein the second hardness is in the range of 67-74 HRC.

3. The system of claim 1 , wherein the bone implant is a bone screw having a threaded head.

4. The system of claim 1 , wherein the opening is a variable angle hole.

5. The system of claim 1 , wherein the first hardness is in the range of 74 HRB-44 HRC.

6. The system of claim 1 , wherein the bone implant is formed of one of stainless steel and CCM.

7. The system of claim 1 , wherein the bone fixation plate is formed of one or more of commercially pure Titanium grades 1, 2, 3 and 4, Ti-6Al-7Nb, Ti-6Al-4V, Ti-6Al-4V ELI, Ti-15Mo, CCM (Co-28Cr-6Mo Alloy) and stainless steel.

8. A bone fixation system, comprising:
a bone screw having a head and a shaft, the head having a proximal end, a distal end spaced from the proximal end in a distal direction, and an outer surface that extends from the distal end to the proximal end, wherein the outer surface of the head carries a thread that is sloped in the distal direction as it extends clockwise about the outer surface with respect to a view in the distal direction, the head further defining a groove that extends into the outer surface along a path that interrupts the thread, wherein the path is sloped counterclockwise as it extends in the distal direction with respect to the view in the distal direction, wherein the outer surface of the head is one of carburized and nitrided so that the head has a first hardness; and
an elongated bone plate that extends along a plate axis and defines a first surface configured to contact bone in an operative configuration, and a second surface opposite the first surface, the bone plate having a plate hole that extends therethrough from the first surface to the second surface, the bone plate having a second hardness,
wherein the first and second hardnesses are selected so that a difference therebetween increases a strength of an interface between the bone screw and the bone plate and avoids burring of the threaded head when the bone screw is inserted through the plate hole of the bone plate.

9. The bone fixation system of claim 8 , wherein the groove extends along a groove axis perpendicular to a longitudinal axis of the bone screw.

10. The bone fixation system of claim 8 , wherein the plate hole is a combination hole.

11. The bone fixation system of claim 8 , wherein the plate hole is a variable angle hole.

12. The bone fixation system of claim 8 , wherein the second surface of the bone plate comprises a plurality of undercuts.

13. The bone fixation system of claim 8 , wherein the plate hole comprises a first tapered portion adjacent the first surface, a second tapered portion adjacent the second surface and a threaded portion extending between the first and second tapered portion.

14. The bone fixation system of claim 8 , further comprising a notch adjacent the distal end of the bone screw.

15. The bone fixation system of claim 8 , further comprising a recess in a proximal end of the bone screw, the recess configured to engage a driving mechanism.

16. The bone fixation system of claim 8 , wherein the shaft is threaded.

17. The bone fixation system of claim 8 , wherein a pitch of threads of the shaft is the same as a pitch of the thread of the head.

18. The bone fixation system of claim 8 , wherein the plate hole is a variable angle hole including a slot extending along a wall of the hole and configured to interrupt threads thereof.

Assignees

• Depuy Synthes Products Inc

Inventors

• Koay Kenny
• Mcmillan Rod
• Kobayashi Kenneth
• Haag Rene
• Limouze Robert
• Wahl Mike
• Rocci Mirko

Classifications

• A61B17/86

  Pins or screws {or threaded wires; nuts therefor (A61B17/72 take precedence)} · CPC title

• A61B17/8605

  Heads, i.e. proximal ends projecting from bone · CPC title

• A61B2017/8655

  with special features for locking in the bone · CPC title

• A61B17/866

  Material or manufacture · CPC title

• A61B17/8635

  Tips of screws · CPC title