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

Patent metadata

Field	Value
Publication number	US-10716609-B2
Application number	US-201816042449-A
Country	US
Kind code	B2
Filing date	Jul 23, 2018
Priority date	Jan 13, 2014
Publication date	Jul 21, 2020
Grant date	Jul 21, 2020

Abstract

A coupling assembly for coupling a rod to a bone anchoring element includes a receiving part having a first end, a second end, a recess having a bottom for receiving the rod, and an accommodation space having an opening at the second end of the receiving part for accommodating a head of the bone anchoring element, and a retainer element configured to be inserted into the receiving part from the first end and to hold at least part of the head, the retainer element having a first portion and a spring portion compressible in an axial direction attached to the first portion. When the retainer element is in the accommodation space in a first position, the spring portion extends in the axial direction from the first portion of the retainer element to an axial position between the first end of the receiving part and the bottom of the recess.

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 the rod, the recess extending axially from the first end down to a bottom of the recess, an accommodation space for accommodating a head of the bone anchoring element, and an opening at the second end of the receiving part to provide access to the accommodation space;
a monolithic retainer element comprising a head contacting portion and a spring portion, wherein when the retainer element is in the receiving part, the head contacting portion is configured to extend into the accommodation space to directly contact the head, while the spring portion is compressible in a direction parallel to the central axis and is configured to extend in an axial direction to a position above the bottom of the recess; and
a pressure element that is separable from the retainer element and that has at least a portion positionable in the accommodation space to exert pressure on the head.

2. The coupling assembly of claim 1 , wherein the spring portion comprises a section that extends in a meandering manner along a longitudinal axis that is substantially parallel to or slightly inclined with respect to the central axis of the receiving part when the retainer element is in the receiving part.

3. The coupling assembly of claim 1 , wherein an outer contour and an inner contour of the spring portion is substantially cylinder segment-shaped.

4. The coupling assembly of claim 1 , wherein the spring portion extends towards the first end of the receiving part to an axial position corresponding to a center of an inserted rod.

5. The coupling assembly of claim 1 , wherein the pressure element is positionable at least partially in the accommodation space to exert pressure directly on the head.

6. The coupling assembly of claim 1 , wherein the spring portion of the retainer element extends at least partially around the pressure element in a circumferential direction when the retainer element and the pressure element are in the receiving part.

7. The coupling assembly of claim 1 , wherein a bore extends from the first end of the receiving part to the accommodation space and is sized such that the pressure element is insertable into the receiving part from the first end.

8. The coupling assembly of claim 1 , wherein a stop is provided for the pressure element to restrict movement of the pressure element towards the first end of the receiving part when the pressure element is in the receiving part.

9. The coupling assembly of claim 8 , wherein the stop also restricts movement of the retainer element towards the first end of the receiving part when the retainer element is in the receiving part.

10. The coupling assembly of claim 1 , wherein when the retainer element and the pressure element are in the receiving part, the retainer element and the pressure element are configured to be coupled together and to remain axially movable relative to each other over a limited distance.

11. 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 that extends at least partially around a longitudinal axis of the retainer element, and a second slit that extends from the second end of the retainer element to the first slit, and wherein the first slit extends away from the second slit and is longer than the second slit.

12. The coupling assembly of claim 11 , wherein the retainer element comprises a third slit extending partially around the longitudinal axis in a direction away from the first slit and the second slit, such that a slit ring is formed at the second end of the retainer element.

13. The coupling assembly of claim 1 , wherein the spring portion of the retainer element comprises two separate spring portions configured to be positioned on either side of the recess of the receiving part when the retainer element is in the receiving part.

14. The coupling assembly of claim 1 , wherein when the retainer element is in the receiving part, the spring portion extends in an oblique or tilted manner relative to the central axis of the receiving part within an enlarged compartment of the receiving part, and wherein the enlarged compartment provides an upper stop and a lower stop for the retainer element.

15. The coupling assembly of claim 1 , wherein when the retainer element and the pressure element are in the receiving part, at least part of the retainer element is configured to extend down to an axial position that is closer to the second end of the receiving part than the entire pressure element is to the second end of the receiving part.

16. A polyaxial bone anchoring device for coupling a rod to a bone, the polyaxial bone anchoring device comprising:
a bone anchoring element comprising a shank for anchoring to bone and a head; and
a 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 the rod, the recess extending axially from the first end down to a bottom of the recess, an accommodation space for accommodating a head of the bone anchoring element, and an opening at the second end of the receiving part to provide access to the accommodation space;
a retainer element comprising a spring portion; and
a pressure element separable from the retainer element;

wherein when the head, the retainer element, and the pressure element are in the receiving part, the spring portion is compressible in a direction parallel to the central axis, and the retainer element and the pressure element are both movable axially in the receiving part and both configured to directly contact the head while also being configured to extend axially to respective positions above the bottom of the recess.

17. The polyaxial bone anchoring device of claim 16 , wherein the retainer element is configured to at least partially encompass the head.

18. The polyaxial bone anchoring device of claim 16 , wherein the spring portion is monolithically formed with other parts of the retainer element.

19. The polyaxial bone anchoring device of claim 16 , wherein when the head, the retainer element, and the pressure element are in the receiving part, the bone anchoring device is configured to assume a locking position where an angular position of the bone anchoring element relative to the receiving part is locked while the spring portion extends to a position above the bottom of the recess.

20. A polyaxial bone anchoring device for coupling a rod to a bone, the polyaxial bone anchoring device comprising:
a bone anchoring element comprising a shank for anchoring to bone and a head; and
a 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 the rod, the recess extending axially from the first end down to a bottom of the recess, an accommodation space for accommodating a head of the bone anchoring element, and an opening at the second end of the receiving part to provide access to the accommodation space; and
a retainer element comprising a monolithic spring portion;

wherein when the head and the retainer element are in the receiving part, the spring portion is elastically compressib

Assignees

• Biedermann Technologies Gmbh

Inventors

• Biedermann Lutz
• Schünemann Achim
• Dandanopoulos Dimosthenis

Classifications

• A61B17/7037 Primary

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

• A61B2560/0443

  Modular apparatus · CPC title

• A61B17/8605 Primary

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

• A61B17/7035 Primary

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