Polyaxial bone anchoring device with enlarged pivot angle

Patent metadata

Field	Value
Publication number	US-9247965-B2
Application number	US-201213586454-A
Country	US
Kind code	B2
Filing date	Aug 15, 2012
Priority date	Aug 18, 2011
Publication date	Feb 2, 2016
Grant date	Feb 2, 2016

Abstract

A polyaxial bone anchoring device includes an anchoring element having a shank and a head, a receiving part having a first end and a second end, a central axis, and an accommodation space for accommodating the head, the accommodation space having an opening at the second end, a sleeve-like insert piece configured to be arranged around a portion of the head and to be arranged in and to pivot in the accommodation space, and a pressure member including a portion configured to exert pressure onto the head, wherein the anchoring element and insert piece are pivotable with respect to the receiving part such that respective angles formed by a central axis of the insert piece with the central axis of the receiving part and a central axis of the anchoring element are adjustable, and can be locked by exerting pressure with the pressure member onto the head.

First claim

What is claimed is:

1. A polyaxial bone anchoring device comprising:
an anchoring element having a shank for anchoring to a bone and a head having a spherically-shaped outer surface portion;
a receiving part having a first end and a second end, a central axis extending through the first end and the second end, a transverse channel at the first end for receiving a rod, and an accommodation space for accommodating the head, the accommodation space having an opening at the second end;
a sleeve-like insert piece having a central axis and a seat for holding at least a portion of the head, wherein the insert piece is configured to be arranged in and to pivot in the accommodation space of the receiving part; and
a pressure member configured to be arranged at least partially in the accommodation space, the pressure member comprising a portion configured to contact the head to exert pressure onto the head;
wherein when the head is in the seat of the insert piece and when the central axis of the receiving part and the central axis of the insert piece are coaxial, the insert piece is insertable into the accommodation space through the opening of the receiving part; and
wherein when the head, the insert piece, and the pressure member are arranged in the receiving part, the anchoring element and insert piece are pivotable with respect to the receiving part, such that respective angles formed by the central axis of the insert piece with the central axis of the receiving part and by the central axis of the insert piece with a central axis of the anchoring element are both adjustable, and the insert piece can be locked relative to the receiving part and the anchoring element at the respective angles by exerting pressure with the pressure member onto the head.

2. The polyaxial bone anchoring device of claim 1 , wherein the receiving part comprises a first engagement portion near the second end, and the insert piece comprises a second engagement portion for engaging the first engagement portion.

3. The polyaxial bone anchoring device of claim 2 , wherein the first engagement portion and the second engagement portion comprise threaded portions.

4. The polyaxial bone anchoring device of claim 2 , wherein the accommodation space has a portion with a largest diameter, and wherein the first engagement portion extends from the opening towards the portion of the accommodation space with the largest diameter.

5. The polyaxial bone anchoring device of claim 2 , wherein the second engagement portion extends over a full outer surface of the insert piece.

6. The polyaxial bone anchoring device of claim 2 , wherein the insert piece is insertable into the accommodation space by engaging the first engagement portion and the second engagement portion, and wherein when the insert piece is inserted in the accommodation space and the first engagement portion and the second engagement portion are disengaged, the insert piece is freely pivotable in the accommodation space.

7. The polyaxial bone anchoring device of claim 2 , wherein when the insert piece is in the receiving part, the first engagement portion and the second engagement portion form a stop to prevent the insert piece from being removed from the receiving part.

8. The polyaxial bone anchoring device of claim 1 , wherein the insert piece is configured to be held on the head by friction.

9. The polyaxial bone anchoring device of claim 1 , wherein the insert piece has a first edge and a second edge, and wherein an engagement portion is provided at the second edge for engaging a tool.

10. The polyaxial bone anchoring device of claim 1 , wherein the accommodation space defines a hollow spherically-shaped portion, and the insert piece has an outer spherically-shaped surface portion.

11. The polyaxial bone anchoring device of claim 1 , wherein when the insert piece is arranged around the head and inserted in the receiving part, the insert piece and the anchoring element are independently pivotable relative to the receiving part when the shank of the anchoring element and an edge of the insert piece are out of contact.

12. The polyaxial bone anchoring device of claim 11 , wherein when the shank of the anchoring element engages the edge of the insert piece, the anchoring element and the insert piece are pivotable together.

13. The polyaxial bone anchoring device of claim 1 , wherein the insert piece has an inner spherical surface portion that forms the seat for the head.

14. The polyaxial bone anchoring device of claim 1 , wherein the insert piece is rigid.

15. The polyaxial bone anchoring device of claim 1 , wherein when the head, the insert piece, and the pressure member are in the receiving part, the pressure member is configured to be held in the receiving part at a position where the pressure member exerts a preload onto the head to clamp the head by friction at a first adjustable position before final locking of an angular position of the anchoring element relative to the receiving part.

16. The polyaxial bone anchoring device of claim 1 , wherein the insert piece is rotationally symmetrical.

17. A method of coupling a rod to a bone or vertebra via a polyaxial bone anchoring device, the bone anchoring device comprising an anchoring element having a shank for anchoring to a bone and a head having a spherically-shaped outer surface portion, a receiving part having a first end and a second end, a central axis extending through the first end and the second end, a transverse channel at the first end for receiving a rod, and an accommodation space for accommodating the head, the accommodation space having an opening at the second end, a sleeve-like insert piece having a central axis and a seat for holding at least a portion of the head, wherein the insert piece is configured to be arranged in and to pivot in the accommodation space of the receiving part, and a pressure member configured to be arranged at least partially in the accommodation space, the pressure member comprising a portion configured to contact the head to exert pressure onto the head, and a fixation element, the method comprising:
connecting the anchoring element to the receiving part by introducing the insert piece and the head through the opening and into the accommodation space of the receiving part, wherein the insert piece and the head are insertable into the accommodation space when the head is in the seat of the insert piece and when the central axis of the receiving part and the central axis of the insert piece are coaxial, and wherein when the head, the insert piece, and the pressure member are arranged in the receiving part, the anchoring element and the insert piece are pivotable with respect to the receiving parts such that respective angles formed by the central axis of the insert piece with the central axis of the receiving part and by the central axis of the insert piece with a central axis of the anchoring element are both adjustable;
inserting the anchoring element into a bone or vertebra;
pivoting the receiving part relative to the anchoring element to adjust the respective angles of the insert piece relative to the receiving part and the anchoring element;
inserting a rod into the channel of the receiving part, wherein the pressure member is arranged between the rod and the anchoring element; and
advancing the fixation element in the channel, such that the fixation element exerts pressure on the rod, the rod exerts pressure on the pressure member, and the pressure member exerts pressure onto the head of the anchoring element, to lock the insert piece relative to the receiving part and

Assignees

• Biedermann Lutz
• Meer Martin
• Biedermann Technologies Gmbh

Inventors

• Biedermann Lutz
• Meer Martin

Classifications

• A61B17/7037 Primary

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

• A61B17/8605

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

• A61B17/70 Primary

  Spinal positioners or stabilisers, e.g. stabilisers comprising fluid filler in an implant · CPC title

• A61B2017/681

  Alignment, compression, or distraction mechanisms · CPC title

• A61B17/86 Primary

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