Coupling assembly for coupling a rod to a bone anchoring element, and polyaxial bone anchoring device

Patent metadata

Field	Value
Publication number	US-9924971-B2
Application number	US-201514596169-A
Country	US
Kind code	B2
Filing date	Jan 13, 2015
Priority date	Jan 13, 2014
Publication date	Mar 27, 2018
Grant date	Mar 27, 2018

Abstract

A coupling assembly for coupling a rod to a bone anchoring element, including a receiving part having first and second ends, a recess at the first end for the rod, and an accommodation space for a head of the bone anchoring element, the accommodation space having an opening at the second end to permit insertion of the head into the receiving part, a retainer element configured to be arranged at least partially in the accommodation space and to hold at least part of the head, and a spring element configured to be arranged at least partially in the accommodation space and to be compressed in an axial direction. The retainer element and the spring element are separate parts. When the retainer element and the spring element are in the accommodation space of the receiving part in a first position, the spring element extends into the recess of the receiving part.

First claim

The invention claimed is:

1. A coupling assembly for coupling a rod to a bone anchoring element, the coupling assembly comprising:
a receiving part having a first, end, a second end, a central axis extending through the first end and the second end, a recess at the first end for receiving a rod, and an accommodation space for accommodating a head of the bone anchoring element, the accommodation space having an opening at the second end configured to permit insertion of the head into the receiving part;
a retainer element configured to be arranged at least partially in the accommodation space and to hold at least part of the head; and
a spring element configured to be arranged at least partially in the accommodation space and to be compressed in an axial direction, wherein the retainer element and the spring element are separate parts;
wherein when the retainer element and the spring element are arranged in the accommodation space of the receiving part in a first position, the spring element extends into the recess of the receiving part to an axial position that is closer to the first end of the receiving part than the entire retainer element is to the first end of the receiving part.

2. The coupling assembly of claim 1 , wherein the spring element extends fully around the central axis.

3. The coupling assembly of claim 1 , wherein the spring element comprises at least one flat strip forming a plurality of waves each having a wave crest portion and a wave trough portion, and wherein the spring element comprises at least two turns around the central axis.

4. The coupling assembly of claim 1 , wherein the spring element comprises a crest-to-crest circular wave spring.

5. The coupling assembly of claim 1 , wherein the retainer element comprises a support surface for supporting the spring element, and wherein in the first position, the spring element is arranged on the support surface and extends in the axial direction to a position higher than a bottom of the recess of the receiving part.

6. The coupling assembly of claim 1 , wherein the retainer element is configured to be restricted from rotating when the retainer element is in the receiving part.

7. The coupling assembly of claim 1 , wherein the retainer element has a first end, a second end, a first slit spaced apart from the second end and extending partially around the central axis, and a second slit that extends from the second end to the first slit, and wherein the first slit extends away from the second slit and is longer than the second slit.

8. The coupling assembly of claim 7 , wherein the retainer element further has a third slit extending partially around the central axis, wherein the first, second, and third slits form a slit ring at the second end of the retainer element.

9. The coupling assembly of claim 1 , further comprising a pressure element configured to be positioned at least partially in the accommodation space and to exert pressure on the head of the bone anchoring element.

10. The coupling assembly of claim 9 , wherein a stop prevents upward movement of the pressure element when the pressure element is arranged in the receiving part.

11. The coupling assembly of claim 9 , wherein a bore extends between the first end of the receiving part and the accommodation space, and wherein the pressure element is movable from the first end of the receiving part through the bore to the accommodation space.

12. The coupling assembly of claim 1 , wherein a bore extends between the first end of the receiving part and the accommodation space, and wherein the retainer element is movable from the first end of the receiving part through the bore to the accommodation space.

13. A polyaxial bone anchoring device comprising the coupling assembly of claim 1 and the bone anchoring element, wherein the bone anchoring element comprises a shank for anchoring to a bone and the head.

14. The polyaxial bone anchoring device of claim 13 , wherein the head of the bone anchoring element comprises a rounded free end surface on a side of the head opposite the shank, wherein the head further has an engagement recess for engagement with a tool, wherein the engagement recess has a plurality of wing portions each extending from a center portion of the rounded free end surface, and wherein in at least one radial direction relative to a longitudinal axis of the bone anchoring element, part of the rounded free end surface extends farther away from the longitudinal axis than the engagement recess extends from the longitudinal axis.

15. The coupling assembly of claim 1 , wherein the spring element is insertable from the first end of the receiving part into the accommodation space.

16. A polyaxial bone anchoring device comprising:
a bone anchoring element comprising a shank for anchoring to a bone and a head; and
a receiving part having a first end, a second end, a central axis extending through the first end and the second end, a recess at the first end for receiving a rod, and an accommodation space at the second end for accommodating the head
wherein a position of the head relative to the receiving part is configured to be locked when the head is in the receiving part; and
wherein the head of the bone anchoring element has a rounded free end surface on a side of the head opposite the shank, and an engagement recess for engagement with a tool, wherein the engagement recess has a plurality of wing portions each extending from a center portion of the rounded free end surface and wherein in at least one radial direction relative to a longitudinal axis of the bone anchoring element, part of the rounded free end surface extends farther away from the longitudinal axis than the engagement recess extends from the longitudinal axis.

17. The polyaxial bone anchoring device of claim 16 , further comprising a retainer element configured to be arranged at least partially in the accommodation space, to hold at least part of the head, and to lock the position of the head relative to the receiving part, wherein when the retainer element and the head are in the receiving part and the head is held in the retainer element, the head extends into the recess of the receiving part and is configured to contact the rod when the rod is received in the recess.

18. The polyaxial bone anchoring device of claim 16 , wherein each of the wing portions of the engagement recess extends in a curved manner from the center of the rounded free end surface.

19. The polyaxial bone anchoring device of claim 16 , wherein the longitudinal axis intersects the center portion of the rounded free end surface.

Assignees

• Biedermann Technologies Gmbh

Inventors

• Biedermann Lutz
• Fischer Bernd

Classifications

• A61B17/8888

  at its central region · CPC title

• A61B17/7037 Primary

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

• A61B2560/0443

  Modular apparatus · CPC title

• A61B17/8615

  at the central region of the screw head · CPC title

• A61B17/7032

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