Dynamic bone anchor and method of manufacturing the same

Patent metadata

Field	Value
Publication number	US-9861415-B2
Application number	US-201314098434-A
Country	US
Kind code	B2
Filing date	Dec 5, 2013
Priority date	Dec 5, 2012
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

A dynamic bone anchor includes an anchor member having first and second ends and a tubular section between the ends, a longitudinal axis extending from the first to second end, an outer surface, and a bone engagement structure for engaging a bone on at least a portion of the outer surface; and a longitudinal core member having a first portion and a second portion configured to be received in the tubular section and to connected to the anchor member, with the first portion configured to be spaced apart from the anchor member and movable with respect to it. The core member is made at least partially of a nickel-titanium (Ni—Ti) based shape memory alloy such that its shape after transitioning from a martensitic to austenitic phase is configured to result in a press-fit connection between the second portion and the anchor member with the second portion in the austenitic phase.

First claim

What is claimed is:

1. A dynamic bone anchor comprising:
an anchor member having an open first end, a second end, and a tubular section between the first end and the second end, a longitudinal axis extending from the first end to the second end, an outer surface and a bone engagement structure for engaging a bone on at least a portion of the outer surface; and
a longitudinal core member having a first portion and a second portion, the second portion having a length along an axial direction of the longitudinal core member configured to be inserted in the tubular section and connected to the anchor member, the first portion extending from the second portion to an end of the core member opposite the second portion, wherein the first portion comprises an anchor head having a diameter greater than a largest outer diameter of the tubular section of the anchor member;
wherein the core member is made at least partially of a first material that comprises a nickel-titanium (Ni—Ti) based shape memory alloy having a temperature sensitive property such that when the second portion of the core member is assembled inside the tubular section of the anchor member, the second portion engages the anchor member at an interface with a low force at a first temperature, and it engages the anchor member at the interface with a high force at a second temperature higher than the first temperature, resulting in a press-fit connection at the interface,
wherein when the second portion of the core member is fully inserted in the tubular section and the interface has the press-fit connection, the open first end of the anchor member is spaced apart from the core member.

2. The dynamic bone anchor of claim 1 , wherein the Ni—Ti based shape memory alloy is in a superelastic metallurgical state under conditions of use.

3. The dynamic bone anchor of claim 1 , wherein the Ni—Ti based shape memory alloy is a Nitinol of the Extra Low Interstitial (ELI) type.

4. The dynamic bone anchor of claim 1 , wherein the anchor member is made of a second material that is different from the first material.

5. The dynamic bone anchor of claim 1 , wherein the core member is fixed to the anchor member by a press-fit connection achieved by a process including manufacturing at least a portion of the core member with a predefined shape, cooling it below the martensite finish temperature M f , deforming it during insertion into the anchor member, and heating it after insertion into the anchor member thereby using the shape memory effect.

6. The dynamic bone anchor of claim 1 , wherein the first portion of the core member comprises an intermediate portion of the core member that has at least partially an outer diameter that is smaller than a greatest diameter of the second portion of the core member, and wherein the intermediate portion is spaced apart from the end of the core member opposite the second portion.

7. The dynamic bone anchor of claim 1 , wherein when the second portion is fully inserted in the tubular section and the interface has the press-fit connection, the first portion of the core member is deflectable from the longitudinal axis in a translational movement in a direction transverse to the longitudinal axis or in a rotational movement around the longitudinal axis.

8. The dynamic bone anchor of claim 1 , wherein the first portion of the core member projects out of the tubular section.

9. The dynamic bone anchor of claim 1 , wherein the anchor head is connectable with other parts of the core member, such that a free end of the first portion of the core member is configured to be connected to the anchor head, and wherein the anchor member is made of a material different than the first material of the core member.

10. The dynamic bone anchor of claim 9 , wherein the free end of the first portion of the core member is fixed to the anchor head by a press-fit connection achieved by a process including manufacturing at least a portion of the core member with a predefined shape, cooling it below the martensite finish temperature M f deforming it during insertion into the anchor head, and heating it after insertion into the anchor head thereby using the shape memory effect.

11. The dynamic bone anchor of claim 1 , wherein the anchor head is monolithic with other parts of the first portion of the core member, and the anchor head having has a spherical segment-shaped portion with an engagement portion configured to engage a tool.

12. The dynamic bone anchor of claim 11 , wherein when the second portion is fully inserted in the tubular section and the interface has the press-fit connection, the anchor head has a distance from the tubular section such that it can move with respect to the tubular section.

13. The dynamic bone anchor of claim 1 , wherein the anchor member comprises a tip at the second end.

14. The dynamic bone anchor of claim 1 , wherein the anchor member is open at the second end and wherein the core member extends through the open second end forming a tip of the bone anchor.

15. A dynamic bone anchor comprising:
an anchor member having an open first end, a second end, and a tubular section between the first end and the second end, a longitudinal axis extending from the first end to the second end, an outer surface and a bone engagement structure for engaging a bone on at least a portion of the outer surface; and
a longitudinal core member having a first portion and a second portion, the second portion having a length along an axial direction of the longitudinal core member configured to be inserted in the tubular section and connected to the anchor member, the first portion extending from the second portion to an end of the core member opposite the second portion, wherein the first portion comprises an anchor head having a diameter greater than a largest outer diameter of the tubular section of the anchor member;
wherein the core member is made at least partially of a first material that comprises a nickel-titanium (Ni—Ti) based shape memory alloy having a temperature sensitive property such that when the second portion of the core member is assembled inside the tubular section of the anchor member, the second portion engages the anchor member at an interface with a low force at a first temperature, and it engages the anchor member at the interface with a high force at a second temperature higher than the first temperature, resulting in a press-fit connection at the interface,
wherein when the second portion of the core member is fully inserted in the tubular section and the interface has the press-fit connection, the first portion of the core member is deflectable in a direction transverse to the longitudinal axis relative to the anchor member or rotatable around the longitudinal axis relative to the anchor member.

16. The dynamic bone anchor of claim 15 , wherein the anchor head is monolithic with other parts of the first portion of the core member.

17. The dynamic bone anchor of claim 15 , wherein the anchor head is connectable with other parts of the core member, such that a free end of the first portion of the core member is configured to be connected to the anchor head.

18. The dynamic bone anchor of claim 6 , wherein the intermediate portion is adjacent the second portion of the core member.

19. The dynamic bone anchor of claim 15 , wherein the first portion of the core member comprises an intermediate portion of the core member, and wherein when the second portion of the core member is fully inserted in the tubular section and the interface has the press-fit connection, the in

Assignees

• Biedermann Technologies Gmbh

Inventors

• Biedermann Lutz
• Matthis Wilfried

Classifications

• A61B2017/00862

  elastic or resilient · CPC title

• A61B17/7035

  Screws or hooks, wherein a rod-clamping part and a bone-anchoring part can pivot relative to each other · CPC title

• A61B17/8685 Primary

  comprising multiple separate parts · CPC title

• A61B17/866

  Material or manufacture · CPC title

• A61B17/8625 Primary

  Shanks, i.e. parts contacting bone tissue · CPC title