Polyaxial bone anchoring device

Patent metadata

Field	Value
Publication number	US-9532809-B2
Application number	US-201514822618-A
Country	US
Kind code	B2
Filing date	Aug 10, 2015
Priority date	Nov 14, 2011
Publication date	Jan 3, 2017
Grant date	Jan 3, 2017

Abstract

A polyaxial bone anchoring device includes a bone anchoring element having a shank and a head, a head receiving part having a first end, an open second end, and a hollow interior portion in communication with the open second end for receiving the head therein, the head receiving part being flexible for clamping the head, a locking ring configured to be mounted around the head receiving part and having a rod receiving portion, a cap configured to be connected to the head receiving part, and a locking element configured to extend from the cap to engage an inserted rod, wherein the head is pivotable in and the cap and the locking ring are rotatable relative to the head receiving part, and wherein when the locking element is tightened, an inserted rod and an angular position of the bone anchoring element are locked relative to the head receiving part.

First claim

What is claimed is:

1. A polyaxial bone anchoring device comprising:
a bone anchoring element having a shank for anchoring to a bone and a head;
a head receiving part having an open first end, an open second end with a bounding edge, and a hollow interior portion in communication with the open first end and the open second end for receiving the head therein, the head receiving part being flexible for clamping the head; and
a locking ring having a first end, a second end, and a rod receiving portion defining a recess for receiving a rod at the first end, wherein the recess has a greatest horizontal width at a first region spaced apart from the first end of the locking ring, and wherein a horizontal width of the recess narrows from the first region in a direction towards the first end of the locking ring;
wherein the locking ring is configured to engage and be positioned around the head receiving part, and wherein when the locking ring is around the head receiving part, the engagement prevents separation of the locking ring from the head receiving part; and
wherein when the head is in the head receiving part with the shank extending through the open second end of the head receiving part and the locking ring is around the head receiving part, the locking ring is movable from a first position wherein the head is pivotable in the head receiving part and the locking ring is rotatable relative to the head receiving part, to a second position wherein the first end of the locking ring is positioned closer to the second end of the head receiving part and wherein the locking ring applies a compressive force to the head receiving part to lock an angular position of the bone anchoring element and a rotational position of the locking ring relative to the head receiving part.

2. The bone anchoring device of claim 1 , wherein when the head is in the head receiving part, the open second end of the head receiving part is configured to permit the bone anchoring element to pivot at a larger maximum pivot angle at a first location of the bounding edge than at a second location of the bounding edge.

3. The bone anchoring device of claim 2 , wherein the bounding edge has a recessed area that facilitates an enlarged pivot angle for the bone anchoring element.

4. The bone anchoring device of claim 1 , wherein the head receiving part comprises a portion with an outer surface that has a smallest diameter nearest the first end and a diameter that increases towards the open second end.

5. The bone anchoring device of claim 1 , wherein the head receiving part comprises a wall with a plurality of slits.

6. The bone anchoring device of claim 1 , wherein the head has a spherical segment-shaped outer surface and the head receiving part defines a spherical segment-shaped seat portion for accommodating the head.

7. The bone anchoring device of claim 6 , wherein the head receiving part has a through hole at the first end with a diameter smaller than a greatest diameter of the head.

8. The bone anchoring device of claim 6 , wherein the head receiving part has a bore at the first end with a diameter greater than the diameter of the head, and wherein between the bore and the seat, a narrowing portion is provided that is configured to expand when the head is inserted through the first end.

9. The bone anchoring device of claim 1 , wherein the locking ring comprises two projections diametrically opposite to each other, the projections each having a recess configured for inserting a rod and for preliminarily holding the inserted rod therein.

10. The bone anchoring device of claim 9 , wherein the recess has a circle segment-shaped contour defining more than half of a circle.

11. The bone anchoring device of claim 1 , further comprising a cap configured to be connected to the head receiving part.

12. The bone anchoring device of claim 11 , wherein the head receiving part comprises a first portion adjacent to the first end comprising an undercut for engagement with the cap.

13. The bone anchoring device of claim 11 , wherein the head receiving part has a groove for engagement with the cap.

14. The bone anchoring device of claim 11 , wherein the cap has a first end configured to face the head receiving part, a second end opposite thereto, and two diametrically opposite recesses for a rod to pass through.

15. The bone anchoring device of claim 11 , wherein the cap has a threaded through hole, and wherein a locking element configured to extend from the cap to engage an inserted rod comprises a set screw configured to be accommodated in the through hole.

16. The bone anchoring device of claim 11 , wherein the cap comprises a side wall having at least one axial slit to render the cap flexible in a radial direction.

17. The bone anchoring device of claim 11 , wherein the cap comprises a circumferential projection with an undercut portion for engagement with a portion of the head receiving part.

18. A modular polyaxial bone anchoring device system comprising:
at least two bone anchoring elements each having a shank for anchoring to a bone and a head, wherein at least two of the bone anchoring elements are shaped differently;
a head receiving part having an open first end, an open second end with a bounding edge, and a hollow interior portion in communication with the open first end and the open second end for receiving the head of one of the bone anchoring elements therein, the head receiving part being flexible for clamping the head; and
a locking ring having a first end, a second end, and a rod receiving portion defining a recess for receiving a rod at the first end, wherein the recess has a greatest horizontal width at a first region spaced apart from the first end of the locking ring, and wherein a horizontal width of the recess narrows from the first region in a direction towards the first end of the locking ring;
wherein the locking rinq is configured to engage and be positioned around the head receiving part, and wherein when the locking ring is around the head receiving part, the engagement prevents separation of the locking ring from the head receiving part;
wherein when the head of one of the bone anchoring elements is in the receiving part with the shank extending through the open second end of the head receiving part and the locking ring is around the head receiving part, the locking ring is movable from a first position wherein the head is pivotable in the head receiving part and the locking ring is rotatable relative to the head receiving part, to a second position wherein the first end of the locking ring is positioned closer to the second end of the head receiving part and wherein the locking ring applies a compressive force to the head receiving part to lock an angular position of the bone anchoring element and a rotational position of the locking ring relative to the head receiving part; and
wherein the bone anchoring elements are interchangeably connectable to the head receiving part.

19. The system according to claim 18 , wherein when the head of one of the bone anchoring elements is in the head receiving part, the open second end of the head receiving part is configured to permit the bone anchoring element to pivot at a larger maximum pivot angle at a first location of the bounding edge than at a second location of the bounding edge.

20. The system according to claim 19 , further comprising a second head receiving part with a first end and an open second end having a bounding edge, wherein the head receiving parts are configured to facilitate different

Assignees

• Biedermann Technologies Gmbh

Inventors

• Biedermann Lutz
• Matthis Wilfried
• Fischer Bernd

Classifications

• A61B17/8605

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

• A61B17/685

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

• A61B17/8685

  comprising multiple separate parts · CPC title

• A61B17/7037 Primary

  wherein pivoting is blocked when the rod is clamped · CPC title

• A61B17/7032

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