Method and tool for assembling a bone anchoring device
A method for assembling a bone anchoring device includes inserting a bone anchoring element in a first holder of a tool and inserting a receiving part in a second holder of the tool, actuating the tool from a first configuration towards a second configuration to insert a head of the bone anchoring element into the receiving part; continuing actuation of the tool towards the second configuration to move a locking ring and a receiving part body of the receiving part relative to each other until the locking ring assumes a second position with respect to the receiving part body in which the locking ring is latched to the receiving part body in a position where the locking ring compresses a portion of the receiving part body to compress the head, such that the head is held in and cannot be removed from the receiving part body and the bone anchoring element is held adjustably at a first angular position relative to the receiving part, and removing the attached bone anchoring element and receiving part from the tool. The tool is configured for the execution of the steps according to the method.
1. A tool for assembling a bone anchoring device, the bone anchoring device comprising a bone anchoring element with a head and a shaft to be anchored in a bone and a receiving part comprising a receiving part body and a locking ring, the tool comprising:
a first holder for holding the bone anchoring element; and
a second holder for holding the receiving part,
wherein the first and second holders are movable relative to each other, such that when the first holder is holding the bone anchoring element and the second holder is holding the receiving part, the movement between the first and second holders is configured to press the bone anchoring element against at least one of the receiving part body or the locking ring, and
wherein at least one of the first holder or the second holder comprises an abutment device which is movable between a first position closer to the other one of the first holder or the second holder and a second position farther away from the other one of the first holder or the second holder, wherein when in the first position the abutment device is configured to resist movement of the receiving part body with respect to the second holder when the first holder is moved towards the second holder to engage the bone anchoring element with the receiving part body, wherein after engagement of the bone anchoring element with the receiving part body, the abutment device is configured to move from the first position to the second position while the second holder is configured to resist movement of the locking ring when the first holder is moved further towards the second holder such that a position of the locking ring relative to the bone anchoring element with the engaged receiving part body is adjusted, and wherein when the abutment device is in the second position, a pressure is applied on the abutment device to urge the abutment device towards the first position.
2. The tool of claim 1 , wherein the second holder comprises the abutment device.
3. The tool of claim 1 , wherein the abutment device comprises:
a main body having a first end, a second end, and a coaxial bore;
a sleeve configured to be movable in the bore; and
a spring member in the sleeve.
4. The tool of claim 3 , wherein the spring member is biased when the abutment device is in the second position.
5. The tool of claim 4 , wherein the spring member is more biased when the abutment device is in the second position than when the abutment device is in the first position.
6. The tool of claim 3 , wherein when the second holder is holding the receiving part, the receiving part body of the receiving part is supported by the sleeve when the abutment device is in the first position.
7. The tool of claim 3 , wherein when the second holder is holding the receiving part, the receiving part body of the receiving part is supported by the sleeve and the locking ring of the receiving part is supported by the main body when the abutment device is in the second position.
8. The tool of claim 3 , wherein the sleeve is closed at an end nearer to the first end of the main body.
9. The tool of claim 3 , wherein the main body comprises a thread at the second end, and wherein a screw is screwable into the thread to support the spring member.
10. The tool of claim 1 , wherein the head of the bone anchoring element, the receiving part body and the locking ring configured for use with the tool are configured such that a force needed to move the locking ring and the receiving part body relative to each other is greater than a force needed to insert the head into the receiving part body.
11. The tool of claim 3 , wherein the spring member is configured such that a force needed to compress the spring member is greater than the force needed to insert the head of the bone anchoring element into the receiving part body and smaller than the force needed to move the locking ring and the receiving part body relative to each other.
12. A tool for assembling a bone anchoring device, the bone anchoring device comprising a bone anchoring element with a head and a shaft to be anchored in a bone, and a receiving part for receiving a rod for coupling the rod to the bone anchoring element, the receiving part comprising a receiving part body with a head receiving portion for accommodating the head of the bone anchoring element and a locking ring configured to be positioned around the head receiving portion, the tool comprising:
a first holder for holding the bone anchoring element; and
a second holder for holding the receiving part,
wherein the first and second holders are movable relative to one another,
wherein at least one of the first holder or the second holder has an abutment device which is movable between a first position closer to the other one of the first holder or the second holder and a second position farther away from the other one of the first holder or the second holder by application of a force in a direction parallel to a direction of the movement between the first and second holders, the abutment device being movable independent from the movement between the first and second holders, and
wherein when the abutment device is in the second position, a pressure is applied on the abutment device to urge the abutment device towards the first position.
13. The tool of claim 12 , wherein the second holder comprises the abutment device.
14. The tool of claim 12 , wherein the abutment device comprises:
a main body having a first end, a second end, and a coaxial bore;
a sleeve configured to be movable in the bore; and
a spring member in the sleeve.
15. The tool of claim 14 , wherein the spring member is biased when the abutment device is in the second position.
16. The tool of claim 14 , wherein the sleeve is closed at an end nearer to the first end of the main body.
17. The tool of claim 14 , wherein the main body comprises a thread at the second end, and wherein a screw is screwable into the thread to support the spring member.
18. The tool of claim 12 , wherein the tool further comprises an insert for receiving the bone anchoring element, the insert configured to be inserted into the first holder.
19. The tool of claim 18 , wherein the first holder has a recess configured to receive the insert.
20. The tool of claim 18 , wherein the insert has at least two recesses.
21. The tool of claim 20 , wherein the recesses on the insert are cylinder-shaped or U-shaped.
22. The tool of claim 20 , wherein the recesses on the insert extend over the whole length of the insert.
23. The tool of claim 18 , wherein the insert is rotatable while in the first holder.
24. The tool of claim 12 , further comprising a handle and lever, wherein the first holder or the second holder is connected to the handle and lever and is configured to be moved towards the other one of the first holder or the second holder by actuation of the handle and lever.
25. The tool of claim 24 , further comprising a frame, wherein a position of the other one of the first holder or the second holder is fixed with respect to the frame.