Instrument for locking and unlocking a head of a bone anchor in a polyaxial bone anchoring device

Patent metadata

Field	Value
Publication number	US-10470805-B2
Application number	US-201715669604-A
Country	US
Kind code	B2
Filing date	Aug 4, 2017
Priority date	Aug 24, 2016
Publication date	Nov 12, 2019
Grant date	Nov 12, 2019

Abstract

An instrument for locking and unlocking a head of a bone anchor relative to a receiving part of a polyaxial bone anchoring device includes a tube assembly with an inner tube and an outer tube at least partially around the inner tube, and an actuator assembly including an actuating mechanism movable from a first orientation to a second orientation to displace the inner tube and the outer tube relative to one another between a first axial position configured to unlock the bone anchoring device such that the head is pivotable relative to the receiving part, and a second axial position configured to lock the head. The actuator assembly is adjustable between a first configuration where the tube assembly assumes the first axial position when the actuating mechanism is moved, and a second configuration where the tube assembly assumes the second axial position when the actuating mechanism is moved.

First claim

What is claimed is:

1. An instrument for locking and unlocking a head of a bone anchor relative to a receiving part of a polyaxial bone anchoring device, the instrument comprising:
a tube assembly having a longitudinal axis and comprising an inner tube configured to engage a first portion of the bone anchoring device, and an outer tube configured to be positioned at least partially around the inner tube and to engage a second portion of the bone anchoring device;
wherein the outer tube and the inner tube are displaceable relative to one another between a first axial position configured to unlock the bone anchoring device such that the head is pivotable relative to the receiving part, and a second axial position configured to lock the head relative to the receiving part; and
an actuator assembly comprising an actuating mechanism having two driving portions that are movable relative to one another from a first orientation to a second orientation to displace the inner tube and the outer tube relative to one another;
wherein the actuator assembly is adjustable relative to the tube assembly between a first configuration wherein the two driving portions are configured to move the tube assembly from the second axial position towards the first axial position when the actuating mechanism is moved from the first orientation to the second orientation, and a second configuration wherein the two driving portions are configured to move the tube assembly from the first axial position towards the second axial position when the actuating mechanism is moved from the first orientation to the second orientation.

2. The instrument of claim 1 , wherein at least part of the actuator assembly is rotatable around the longitudinal axis relative to the tube assembly, to adjust the actuator assembly between the first configuration and the second configuration.

3. The instrument of claim 1 , wherein the actuator assembly is removably connectable to the tube assembly.

4. The instrument of claim 3 , wherein at least part of the actuator assembly is rotatable around the longitudinal axis relative to the tube assembly, to adjust the actuator assembly between the first configuration and the second configuration, and wherein the at least part of the actuator assembly is further rotatable to a third configuration wherein the actuator assembly is connectable to and/or removable from the tube assembly.

5. The instrument of claim 1 , wherein the actuating mechanism further comprises a lever, and wherein the first orientation corresponds to a first position of the lever and the second orientation corresponds to a second position of the lever.

6. The instrument of claim 1 , wherein when the actuating mechanism is moved from the first orientation to the second orientation, the two driving portions are axially displaced relative to one another to adjust an axial spacing between the two driving portions.

7. The instrument of claim 6 , wherein when the actuating mechanism is at the first orientation, the two driving portions contact one another in the axial direction.

8. The instrument of claim 6 , wherein the tube assembly comprises two driven portions configured to be driven by the two driving portions.

9. The instrument of claim 8 , wherein the two driven portions are spaced apart circumferentially relative to one another, such that when the actuator assembly is at the first configuration, the two driving portions are at a same circumferential position as a first one of the two driven portions, and when the actuator assembly is at the second configuration, the two driving portions are at a same circumferential position as a second one of the two driven portions.

10. The instrument of claim 9 , wherein a gap is provided between the two circumferentially spaced apart driven portions to facilitate passing of the driving portions therebetween.

11. The instrument of claim 1 , wherein the actuator assembly further comprises an outer sleeve and an inner sleeve that are axially displaceable relative to one another when the actuating mechanism is adjusted between the first and second orientations.

12. The instrument of claim 11 , wherein the actuating mechanism further comprises a toggle lever with a first lever arm hingedly connected to the outer sleeve and a second lever arm hingedly connected to the inner sleeve.

13. The instrument of claim 11 , wherein the outer sleeve comprises a first driving portion of the two driving portions and the inner sleeve comprises a second driving portion of the two driving portions axially aligned with the first driving portion.

14. The instrument of claim 1 , wherein the actuator assembly further comprises a spring member that biases the actuating mechanism towards the first orientation.

15. The instrument of claim 1 , wherein the actuator assembly further comprises a grip portion to facilitate exerting of a counter force when the actuating mechanism is moved from the first orientation to the second orientation.

16. The instrument of claim 1 , further comprising a stopper member movable along the longitudinal axis of the tube assembly between a first position wherein a rotational movement of the tube assembly relative to a connected polyaxial bone anchoring device is restricted, and a second position wherein the rotational movement of the tube assembly relative to the connected polyaxial bone anchoring device is not restricted.

17. A system comprising the instrument of claim 1 and a polyaxial bone anchoring device comprising:
the bone anchor for anchoring in a bone;
the receiving part for receiving the head of the bone anchor; and
a clamping device comprising a pressure exerting surface that is movable relative to the receiving part to apply pressure on the head when the head is held in the receiving part to lock the head in the receiving part;
wherein the receiving part comprises an engagement surface configured to be engaged by a corresponding engagement surface at the inner tube, and the clamping device comprises an engagement surface configured to be engaged by a corresponding engagement surface at the outer tube, to facilitate movement of the clamping device relative to the receiving part when the outer tube and the inner tube are displaced relative to one another.

18. The system of claim 17 , wherein the receiving part further comprises a rod receiving portion having a recess for receiving a rod, wherein the engagement surface at the receiving part is formed at the rod receiving portion, and a head receiving portion for accommodating the head of the bone anchor, the head receiving portion being flexible for inserting and clamping the head, and wherein the clamping device comprises a locking ring configured to be arranged around the head receiving portion, wherein the engagement surface at the clamping device is formed at the locking ring.

19. A method for using an instrument to couple a rod to a bone via a polyaxial bone anchoring device comprising a bone anchor for anchoring in the bone, a receiving part for receiving a head of the bone anchor, and a fixation element, wherein the instrument is for locking and unlocking the head relative to the receiving part and comprises a tube assembly having a longitudinal axis and comprising an inner tube configured to engage a first portion of the bone anchoring device, and an outer tube configured to be positioned at least partially around the inner tube and to engage a second portion of bone anchoring device, wherein the outer tube and the inner tube are displaceable relative to one another between a first axial p

Assignees

• Biedermann Technologies Gmbh

Inventors

• Biedermann Timo
• Dold Kevin
• Schünemann Achim

Classifications

• A61B17/708

  with tubular extensions coaxially mounted on the bone anchors · CPC title

• A61B17/7082

  for driving, i.e. rotating, screws or screw parts specially adapted for spinal fixation, e.g. for driving polyaxial or tulip-headed screws · CPC title

• A61B17/7037 Primary

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

• A61B17/7076

  for driving, positioning or assembling spinal clamps or bone anchors specially adapted for spinal fixation · CPC title

• A61B17/7079

  Tools requiring anchors to be already mounted on an implanted longitudinal or transverse element, e.g. where said element guides the anchor motion · CPC title