Stylet control handles and methods of using the same
Disclosed herein are stylet control handles and related methods for extending and retracting a stylet during insertion of a bone anchor, and for providing a visual indication of the extent of extension of the stylet.
1. A handle for extending and retracting a stylet during insertion of a bone anchor, the handle comprising:
a handle body;
a cap assembly disposed at a proximal end of the handle body, wherein the cap assembly is configured to be releasably fixed to the stylet;
a cover disposed over at least a portion of the handle body; and
a lever assembly comprising a lever,
wherein the lever is operatively coupled to the cap assembly, and is configured to pivotably extend from an outer surface of the cover;
wherein a portion of the cap assembly is configured to rotate relative to the cover, to move between a first, docking mode and a second, extended mode,
wherein, in the second, extended mode, the lever is configured to pivot away from the handle body in response to translation of the portion of the cap assembly and the stylet in a distal direction, and
wherein the stylet is configured to retract in a proximal direction in response to the lever pivoting toward the handle body.
2. The handle of claim 1 , wherein the cap assembly comprises:
a cap body;
a knob coupled to and disposed proximally relative to the cap body; and
a cap matingly engaged with a proximal end of the knob,
wherein in the first, docking mode, the cap is constrained from translation in a distal direction relative to the cover, and the stylet is constrained from translation in a distal direction relative to a bone anchor, and
wherein in the second, extended mode, the cap is configured to translate distally relative to the cover, and such distal translation of the cap causes the stylet to extend beyond a distal tip of the bone anchor.
3. The handle of claim 2 , wherein the knob further comprises a retention button configured to releasably constrain an axial position of the stylet relative to the cap assembly.
4. The handle of claim 2 , wherein the knob is configured to rotate relative to the cover to move between the first, docking mode and the second, extended mode.
5. The handle of claim 4 , further comprising a rack member configured to couple the cap assembly to the lever assembly,
wherein the rack member is coupled at a proximal end thereof to the cap assembly, and extends distally from the cap assembly,
wherein the cap body and the rack member are rotationally and translationally fixed relative to one another, and
wherein the rack member is disposed within the handle body.
6. The handle of claim 5 , wherein the rack member further comprises a threaded portion at a distal end thereof.
7. The handle of claim 5 , wherein the lever assembly further comprises a first gear configured to couple the rack member at a distal end thereof to the lever.
8. The handle of claim 7 , wherein the first gear is coupled to the lever by a connector member, or the first gear is formed integrally with the lever.
9. The handle of claim 7 , where in the lever assembly further comprises a second gear configured to couple the rack member to the lever via the first gear.
10. The handle of claim 9 , wherein the first gear is configured to rotate in one of a clockwise or a counter clockwise direction, and the second gear is configured to rotate in the opposite of the clockwise or the counterclockwise direction.
11. The handle of claim 9 , wherein each of the first gear and the second gear have gear teeth on at least part of the circumference of the respective gear.
12. The handle of claim 9 , further comprising a ball detent configured to engage with the second gear, thereby limiting a pivoting motion of the lever assembly, and constraining an axial position of the stylet in the docking mode.
13. The handle of claim 12 , wherein the ball detent is configured to directly limit rotation of the second gear and indirectly limit rotation of the first gear.
14. The handle of claim 12 , wherein the ball detent is configured to engage with one or more corresponding grooves on the second gear.
15. The handle of claim 5 , wherein the handle body further comprises an inner shelf, wherein the inner shelf is configured to matingly engage with a distal end of the rack member in the extended mode, and
wherein the inner shelf is configured to not matingly engage with the distal end of the rack member, and to limit distal movement of the rack member in the docking mode.
16. The handle of claim 15 , further comprising a pin disposed in a corresponding groove in the rack member, the pin being configured to limit rotation of the knob to one direction.
17. The handle of claim 1 , wherein the cover further comprises a window having a shape complementary to that of the lever, the window being configured to receive the lever when it has pivoted toward the handle body.
18. The handle of claim 1 , further comprising a ratchet assembly disposed at least partly within the cover, wherein the cover is rotationally fixed relative to the ratchet assembly and the lever assembly, and the ratchet assembly is configured to couple to a screw driver.
19. The handle of claim 18 , further comprising a sleeve disposed about the ratchet assembly, wherein the sleeve is fixedly attached to an inner surface of the cover.
20. The handle of claim 1 , wherein the cover further comprises a feedback element configured to provide a user with audio or tactile feedback as the cap assembly rotates or translates.