Monoplanar bone anchoring device with selectable pivot plane

1. A bone anchoring device comprising:

a receiving part for receiving a rod, the receiving part having a longitudinal axis, a first bore coaxial with the longitudinal axis and a second bore;

an anchoring element having a first end for insertion into a bone and a second end positionable in the second bore, the second end including a head;

a guiding member configured to rotate in the first bore;

a locking device comprising a first locking element configured to act on the guiding member when the guiding member is in the first bore to fix the rotational position of the guiding member and a second locking element configured to act on the head when the head is in the second bore to fix the head;

wherein the head is guided by the guiding member and when the head and the guiding member are assembled in the receiving part a form-fit connection limits a movement of the anchoring element to a single plane;

wherein when the first locking element and the guiding member are assembled in the receiving part, the rotational position of the guiding member can be fixed in at least two or more positions within the receiving part; and

wherein when the rotational position of the guiding member is fixed by the first locking element, the anchoring element is movable relative to the receiving part in a limited angular range about the longitudinal axis, the angular range lying in the single plane.

2. The bone anchoring device of claim 1 , wherein the receiving part comprises a U-shaped recess for receiving the rod, the U-shaped recess defining two open legs wherein an internal thread is provided at the open legs.

3. The bone anchoring device of claim 2 , wherein the first locking element comprises an outer thread which is configured to cooperate with the internal thread at the open legs and wherein the first locking element comprises a coaxial bore comprising an internal thread configured to cooperate with an outer thread on the second locking element.

4. The bone anchoring device of claim 1 , further comprising a pressure element having a recess shaped to receive the rod, the pressure element configured to be arranged between the guiding member and the locking device in the receiving part.

5. The bone anchoring device of claim 4 , wherein the pressure element is configured to exert pressure on the guiding member but not on the head.

6. The bone anchoring device of claim 4 , wherein the pressure element is substantially cylindrical and has a first end facing the locking device and a second end facing the head when the bone anchoring device is assembled and wherein the pressure element comprises a recess at the second end sized so that a portion of the head is capable of being accommodated therein without contacting the pressure element.

7. The bone anchoring device of claim 6 , wherein the pressure element comprises a recess at its first end sized so that a portion of the second locking element is capable of extending therein without contacting the pressure element.

8. The bone anchoring device of claim 1 , wherein an edge defining the second bore is asymmetric to permit the bone anchoring element to pivot at a larger angle relative to the longitudinal axis at a first location of the edge than at another location of the edge.

9. The bone anchoring device of claim 8 , wherein the receiving part has a countersunk area at the edge defining the second bore.

10. The bone anchoring device of claim 1 , wherein the head has a substantially spherical segment shape in which the rotational axis of the sphere extends perpendicular to the shank axis.

11. A method of using a bone anchoring device, the bone anchoring device comprising an anchoring element having a first end for insertion into a bone and a second end, the second end including a head; a receiving part for receiving a rod, the receiving part having a longitudinal axis, a first bore coaxial with the longitudinal axis and a second bore; a guiding member and a locking device comprising a first locking element and a second locking element; wherein the head and the guiding member are configured to have a form-fit connection that limits a movement of the anchoring element to a single plane; the method comprising:

inserting the anchoring element into the receiving part;

positioning the second end of the anchoring element in the second bore of the receiving part;

inserting the guiding member into the first bore, wherein the guiding member is rotatable inside the first bore;

assembling the head with the guiding member to form the form-fit connection between the head and the guiding member that limits the movement of the anchoring element to a single plane;

inserting a rod into the first bore;

assembling the first locking element and the guiding member in the receiving part such that the rotational position of the guiding member can be fixed in at least two or more positions within the receiving part;

fixing the rotational position of the guiding member with the first locking member such that the anchoring element is movable relative to the receiving part in a limited angular range about the longitudinal axis, the angular range lying in the single plane; and

fixing the head with the second locking member.

12. The bone anchoring device of claim 1 , wherein when the head and the guiding member are assembled in the receiving part, a portion of the head projects out of the guiding member in a direction of the first locking member when the first locking member is in the receiving part.

13. The bone anchoring device of claim 1 , further comprising a seat member having a bore and a seat for the head, the seat member configured to be assembled and mounted to the receiving part, wherein the seat member comprises an edge defining the bore of the seat member that is asymmetric to permit the bone anchoring element to pivot at a larger angle relative to the longitudinal axis at a first location of the edge than at another location of the edge.

14. The bone anchoring device of claim 1 , wherein the seat member is configured to rotate in the second bore.

15. The bone anchoring device of claim 1 , wherein the seat for the head is spherical.

16. The bone anchoring device of claim 1 , wherein the seat member has a recess at its edge for a form-fit connection to the head.