Bone anchoring device

• US 20070055240A1
• Filed: 07/07/2006
• Published: 03/08/2007
• Est. Priority Date: 07/08/2005
• Status: Active Grant

• Current Assignee: Biedermann Technologies GmbH & Co. KG
• Original Assignee: Biedermann Technologies GmbH & Co. KG
• Inventors: Matthis, Wilfried, Biedermann, Lutz, Harms, Juergen
• Granted Patent: US 8,034,089 B2
• Time in Patent Office: Days
• US Class Current: 606/308
• CPC Class Codes: A61B 17/7032 Screws or hooks with U-shaped head or back through which longitudinal rods pass
• CPC Class Codes: A61B 17/7037 wherein pivoting is blocked when the rod is clamped
• CPC Class Codes: A61B 17/7067 Devices bearing against one or more spinous processes and also attached to another part of the spine; Tools therefor
• CPC Class Codes: A61B 17/7076 for driving, positioning or assembling spinal clamps or bone anchors specially adapted for spinal fixation
• CPC Class Codes: A61B 17/7085 for insertion of a longitudinal element down one or more hollow screw or hook extensions, i.e. at least a part of the element within an extension has a component of movement parallel to the extension's axis
• CPC Class Codes: A61B 17/8605 Heads, i.e. proximal ends projecting from bone
• CPC Class Codes: A61B 17/861 specially shaped for gripping driver
• CPC Class Codes: A61B 17/8685 comprising multiple separate parts
• CPC Class Codes: A61B 17/8875 Screwdrivers, spanners or wrenches

Abstract

A bone anchoring device has an anchoring element, a receiving portion, and a pressure element. The anchoring element includes a shank to be anchored in a bone or a vertebra and a head, the head having an exterior surface with a spherical segment-shaped portion. The shank and the head are separate parts. The receiving portion includes a first end, a second end opposite to the first end, a longitudinal axis passing through the two ends, a bore coaxial with the longitudinal axis, and a first region adjacent to the second end for receiving a spherical segment-shaped section of the head. The pressure element exerts pressure on the head to lock the head in the receiving portion. The head has a hollow inner portion to receive a free end portion of the shank and wherein the head and the end portion are formed such that the end portion can be elastically clamped by the head.

Claims

1. A bone anchoring device comprising:

an anchoring element comprising a shank to be anchored in a bone or a vertebra and a head, the head having an exterior surface with a spherical segment-shaped portion, wherein said shank and said head are separate parts;

a receiving portion comprising a first end, a second end opposite to the first end, a longitudinal axis passing through the two ends, a bore coaxial with the longitudinal axis, and a first region adjacent to the second end for receiving the spherical segment-shaped section of said head; and

a pressure element which exerts pressure on said head to lock said head in the receiving portion, the pressure element being of cylindrical construction and having a spherical recess on a side facing the head, which cooperates with the head when pressure is exerted;

wherein said head has a hollow inner portion to receive a free end portion of said shank, wherein said head and said end portion are formed such that the end portion is elastically clamped by said head while the head and end portion are located in the receiving portion and the head and the receiving portion are unlocked to each other, and wherein said end portion is conically shaped, the diameter increasing towards a free end of the shank opposite a second end of the shank.

2. The bone anchoring device of claim 1, wherein the hollow inner portion has a mating shape corresponding to the conically shaped end portion

3. The bone anchoring device of claim 1, wherein said conical shape is a truncated cone.

4. The bone anchoring device of claim 1, wherein a cone angle of the conically shaped end portion is selected such that a self-locking occurs between the head and the end portion.

5. The bone anchoring device of claim 4, wherein said angle is between about 2 and 10 degrees.

6. The bone anchoring device according to claim 1, wherein the head comprises a spring-like edge facing towards the end portion of the shank.

7. The bone anchoring device of claim 1, wherein the head comprises one or more slits which are directed substantially parallel to the rotational axis of the head and are open on a side facing the end portion of the shank.

8. The bone anchoring device of claim 1, wherein the hollow inner portion of the head which receives the end portion of the shank forms an abutment for the free end of the end portion.

9. The bone anchoring device of claim 1, wherein the hollow inner portion is shaped as a hollow truncated cone and extends from one end of the head to an opposite end.

10. The bone anchoring device of claim 1, wherein said receiving portion has a U-shaped recess extending from the first end in the direction of the second end which forms a channel to receive a rod.

11. A tool for use with an anchoring element

the anchoring element comprising a shank to be anchored in a bone or a vertebra and a head, the head having an exterior surface with a spherical segment-shaped portion, wherein said shank and said head are separate parts;

and

a receiving portion comprising a first end, a second end opposite to the first end, a longitudinal axis passing through the two ends, a bore coaxial with the longitudinal axis, and a first region adjacent to the second end for receiving the spherical segment-shaped section of said head;

the tool comprising

a longitudinal member,

a first arm extending from the longitudinal member, the first arm having a fixed position on the longitudinal member, and

a second arm extending from the longitudinal member, the second arm being positionable relative to the first arm in a longitudinal direction of the longitudinal member.

12. The tool of claim 11, wherein said second arm is slidingly mounted on said longitudinal member.

13. The tool of claim 11, wherein said second arm or said first arm is fork-shaped.