Polyaxial bone anchoring device

Patent metadata

Field	Value
Publication number	US-9585698-B2
Application number	US-201213618000-A
Country	US
Kind code	B2
Filing date	Sep 14, 2012
Priority date	Dec 27, 2010
Publication date	Mar 7, 2017
Grant date	Mar 7, 2017

Abstract

A polyaxial bone anchoring device includes
an anchoring element having a shaft and a head; a receiving part having a channel for receiving a rod therein, a coaxial bore and a seat portion for receiving the head; a pressure element having a head contacting surface portion; wherein the head is pivotable with respect to the receiving part and can be fixed at an angle by exerting pressure via the pressure element onto the head, and wherein the head has an oversize with respect to the head contacting surface portion such that an interference fit is achieved that clamps the head by the friction between the head and the head contacting surface portion. The curved outer surface portion has a largest diameter and the head contacting surface contacts the head at least in a region including the largest diameter.

First claim

The invention claimed is:

1. A polyaxial bone anchoring device comprising:
an anchoring element having a shaft for anchoring to a bone, a head having a curved outer surface portion, and a longitudinal axis extending through the shaft and the head;
a receiving part having a top end and a bottom end, a channel for receiving a rod therein, a coaxial bore extending from the top end in a direction of the bottom end, a seat portion for receiving the head at the bottom end, and a recess at an inner wall of the receiving part; and
a pressure element configured to be arranged within the bore between the head of the anchoring element and the top end of the receiving part, the pressure element having a head contacting surface portion configured to contact the curved outer surface portion of the head, and comprising a projection,
wherein, when the head is seated in the seat portion, the recess is entirely between a plane of the receiving part and the bottom end of the receiving part, the plane being defined by the curved outer surface portion of the head having a greatest width or diameter of the head in a direction perpendicular to the longitudinal axis,
wherein, when the head engages the head contacting surface portion and the pressure element is in the receiving part, the head is pivotable with respect to the receiving part and the projection engages a surface of the recess facing toward the bottom end of the receiving part such that the head is prevented from moving toward the top end of the receiving part, and
wherein the head is configured to be locked at an angle by exerting pressure via the pressure element onto the head.

2. The polyaxial bone anchoring device of claim 1 , wherein the receiving part comprises a plurality of recesses offset from each other by 180°.

3. The polyaxial bone anchoring device of claim 1 , wherein the pressure element further comprises a plurality of projections which are configured to contact the head at opposite sides.

4. The polyaxial bone anchoring device of claim 1 , wherein the pressure element is substantially cylindrical and has an upper end, a lower end, and a recess at the lower end, wherein the head contacting surface portion is at the lower end.

5. The polyaxial bone anchoring device of claim 1 , wherein the seat portion comprises an upper edge defining an opening having a greatest width or diameter that is less than the greatest width or diameter of the head, and
wherein, when the head is seated in the seat portion, the upper edge is positioned closer to the top end of the receiving part than the portion of the head having the greatest width or diameter to prevent movement of the head towards the top end.

6. The polyaxial bone anchoring device of claim 1 , further comprising a fixation device configured to cooperate with the receiving part to lock the head in the seat portion and to fix a rod in the channel.

7. The polyaxial bone anchoring device of claim 1 , wherein the greatest width or diameter of the head is greater than a greatest width or diameter of an inner space defined by the head contacting surface portion of the pressure element when the head contacting surface portion is unbiased.

8. The polyaxial bone anchoring device of claim 1 , wherein the projection comprises an outwardly extending nose extending in the direction perpendicular to the longitudinal axis away from the head contacting surface portion, and
wherein the nose is configured to engage the recess.

9. The polyaxial bone anchoring device of claim 8 , wherein the recess has a height in a direction parallel to the coaxial bore that is greater than a thickness of the outwardly extending nose to permit further downward movement of the pressure element to lock the head.

10. A method of coupling a rod to a bone via a polyaxial bone anchoring device, the bone anchoring device comprising an anchoring element having a shaft for anchoring to a bone, a head having a curved outer surface portion, and a longitudinal axis extending through the shaft and the head, a receiving part having a top end and a bottom end, a channel for receiving a rod therein, a coaxial bore extending from the top end in a direction of the bottom end, a seat portion for receiving the head at the bottom end, and a recess at an inner wall of the receiving part, and a pressure element configured to be arranged within the bore between the head of the anchoring element and the top end of the receiving part, having a head contacting surface portion configured to contact the curved outer surface portion of the head, and comprising a projection, the recess being entirely between a plane of the receiving part and the bottom end of the receiving part, the plane being defined by a greatest width or diameter of the head in a direction perpendicular to the longitudinal axis when the head is seated in the seat portion, the method comprising:
inserting the bone anchoring device into a bone when the head and the pressure element are in the receiving part with the pressure element being between the head of the anchoring element and the top end of the receiving part, the curved outer surface portion of the head and the head contacting surface portion of the pressure element are in contact, and the projection engages a surface of the recess facing toward the bottom end of the receiving part such that the head is prevented from moving towards the top end of the receiving part;
applying a force onto the receiving part or the anchoring element that is greater than a force of friction between the head and pressure element to adjust an angular position between the anchoring element and the receiving part;
inserting a rod into the channel; and
advancing a fixation device into the channel to push the rod against the pressure element and the pressure element against the head to lock the angular position between the bone anchoring element and the receiving part.

11. The method of claim 10 , wherein prior to inserting the bone anchoring device into the bone, the method further comprises:
engaging the head and the pressure element such that the head contacting surface portion of the pressure element contacts the curved outer surface portion of the head; and
inserting the head and the pressure element into the receiving part such that the projection snaps into the recess.

12. The method of claim 11 , wherein the head and the pressure element are engaged prior to inserting the head and the pressure element into the receiving part.

13. The method of claim 11 , wherein the head and the pressure element are engaged after inserting the head and the pressure element into the receiving part.

14. The method of claim 11 , wherein when the head and the pressure element are engaged and the projection is snapped into the recess, the head and the pressure element are prevented from moving towards the top end of the receiving part.

15. A polyaxial bone anchoring device comprising:
an anchoring element having a shaft for anchoring to a bone, a head having a curved outer surface portion, and a longitudinal axis extending through the shaft and the head, the head having a greatest width or diameter in a direction perpendicular to the longitudinal axis;
a receiving part having a top end and a bottom end, a channel for receiving a rod therein, a coaxial bore extending from the top end in a direction of the bottom end, and a seat portion for receiving the head at the bottom end, the receiving part being configured such that the bone anchoring element is received through the top end; and
a pressure element configured to be arranged within the bore, the pressure element having a head contacting s

Assignees

• Biedermann Lutz
• Matthis Wilfried
• Kegel Michael
• Biedermann Technologies Gmbh

Inventors

• Biedermann Lutz
• Matthis Wilfried
• Kegel Michael

Classifications

• A61F2/44

  for the spine, e.g. vertebrae, spinal discs · CPC title

• Y10S606/913

  Monolithic · CPC title

• A61B17/7037 Primary

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

• A61B17/70 Primary

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

• A61F2/4455

  for the fusion of spinal bodies, e.g. intervertebral fusion of adjacent spinal bodies, e.g. fusion cages (intervertebral discs A61F2/442) · CPC title