NON-FUSION SCOLIOSIS EXPANDABLE SPINAL ROD

• US 20110137347A1
• Filed: 12/01/2010
• Published: 06/09/2011
• Est. Priority Date: 12/01/2009
• Status: Active Grant

• Current Assignee: Hand Innovations LLC (Johnson & Johnson)
• Original Assignee: Synthes USA LLC (Johnson & Johnson)
• Inventors: HUNZIKER, MARKUS
• Granted Patent: US 8,568,457 B2
• Time in Patent Office: Days
• US Class Current: 606/258
• CPC Class Codes: A61B 17/7014 with means for adjusting the distance between two screws or hooks
• CPC Class Codes: A61B 17/7016 electric or electromagnetic means
• CPC Class Codes: A61B 17/7216 for bone lengthening or compression A61B17/7258 takes precedence
• CPC Class Codes: A61B 2017/00398 using powered actuators, e.g. stepper motors, solenoids
• CPC Class Codes: A61B 2017/00407 Ratchet means
• CPC Class Codes: A61B 2017/00876 magnetic
• CPC Class Codes: A61B 2017/00991 Telescopic means
• CPC Class Codes: A61B 2017/0256 for the spine

Abstract

A growing rod for mounting between attachment mechanisms that are secured to anatomical structures of a patient having scoliosis. The growing rod includes a base rod having an attachment end, an extendable rod that is translatable relative to the base rod along a longitudinal axis and a housing enclosing at least a portion of the extendable rod therein. A magnet is rotatably mounted within the housing and is enclosed by a top magnet cover and a bottom magnet cover. The magnet includes a first pole and a second pole. A gear reduction mechanism is associated with the magnet and the extendable rod. The gear reduction mechanism reduces an output rotation to the extendable rod relative to an input rotation from the magnet.

Claims

1. A growing rod, comprising:

a base rod having an attachment end;

an extendable rod being translatable relative to the base rod along a longitudinal axis;

a housing enclosing at least a portion of the extendable rod therein;

a magnet rotatably mounted within the housing and enclosed by a top magnet cover and a bottom magnet cover, the magnet including a first pole and a second pole; and

a gear reduction mechanism associated with the magnet and the extendable rod, the gear reduction mechanism reducing an output rotation to the extendable rod in comparison to an input rotation from the magnet.

2. The growing rod of claim 1, wherein the extendable rod moves along the longitudinal axis substantially without rotation relative to the base rod.

3. The growing rod of claim 1, wherein the base rod and the extendable rod each include an attachment end that are attached to attachment points within a patient'"'"'s body.

4. The growing rod of claim 3, wherein the attachment points are one of a pedicle screw, a hook and a cradle.

5. The growing rod of claim 1, wherein the gear reduction mechanism further comprises:

a carrier gear having external gear teeth and internal gear teeth;

a fork;

a fork pin pivotally mounting the fork to a gear housing;

a ratchet arm that is pivotal within the gear housing about the fork pin; and

a pawl that is mounted within the ratchet arm,

wherein the internal gear teeth mesh with threads on the extendable rod to cause the extendable rod to move relative to the base rod along the longitudinal axis.

6. The growing rod of claim 5, wherein rotation of the magnet by a magnetic field causes the ratchet arm to drive the pawl that pivots the carrier gear about the longitudinal axis by an interaction of pawl teeth and the external threads.

7. The growing rod of claim 5, further comprising a locking mechanism that engages the pawl, wherein a position of the locking mechanism within the pawl blocks a rotational direction of the carrier gear.

8. The growing rod of claim 7, wherein an unblocked rotational direction causes the extendable rod to translate in a direction away from the base rod along the longitudinal direction.

9. The growing rod of claim 7, wherein an unblocked rotational direction causes the extendable rod to translate in a direction toward the base rod along the longitudinal direction.

10. The growing rod of claim 1, wherein the growing rod, with an exception of the magnet, is constructed of a non-magnetizable material.

11. The growing rod of claim 10, wherein the non-magnetizable material comprise one of titanium, a titanium alloy material, a cobalt-chromium material and a polymeric material.

12. The growing rod of claim 1, wherein the extendable rod is moved relative to the base rod along the longitudinal axis by passing a magnetic field in proximity to the growing rod to cause the magnet to rotate about the longitudinal axis.

13. The growing rod of claim 1, wherein the gear reduction mechanism further comprises:

a gear housing having internal gear teeth;

a gear wheel having external gear teeth;

a driver wheel having diver pins fixed thereto and that are fitted within the gear wheel, the driver wheel including a threaded shaft; and

a carrier that mates with the threaded shaft and mates with extendable rod by torque pins.

14. The growing rod of claim 13, wherein the external gear teeth are mismatched with the internal gear teeth such that the rotation of the gear wheel causes the external gear teeth and the internal gear teeth to mesh, and wherein the gear wheel rotates less than a full rotation for each full rotation of the magnet.

15. The growing rod of claim 14, wherein the gear wheel rotates approximately one-fifteenth of a rotation for each full rotation of the magnet.

16. The growing rod of claim 13, wherein rotation of gear wheel is transmitted to the driver wheel through the driver pins, and wherein rotation of the driver wheel causes rotation of the threaded shaft and the carrier to move the extendable rod out of the housing.

17. The growing rod of claim 13, further comprising a slider that is fixed to housing, the slider including a pair of slots that receive the torque pins to limit rotational movement of the extendable rod.

18. The growing rod of claim 1, wherein the gear reduction mechanism further comprises:

a gear housing having internal gear teeth;

a gear wheel having external gear teeth;

a driver wheel having diver pins fixed thereto that are fitted within the gear wheel, the driver wheel including a threaded shaft; and

a carrier that mates with the threaded shaft and to extendable rod by a keyway.

19. The growing rod of claim 18, wherein rotation of gear wheel is transmitted to the driver wheel through the driver pins, and wherein rotation of the driver wheel causes rotation of the threaded shaft and the carrier to move the extendable rod out of the housing.

20. The growing rod of claim 18, wherein the interaction of the carrier and the extendable rod through the keyway limits rotational movement of the extendable rod.

21. A growing rod, comprising:

a housing;

a fixed rod that is attached to the housing at a first end of the housing;

an extendable rod that moves along a longitudinal axis of the growing rod and extending from a second end of the housing;

a magnet mounted within the housing; and

a gear reduction mechanism,

wherein movement of the magnet caused by an external magnetic field is input to the gear reduction mechanism, and wherein the gear reduction mechanism reduces the input movement to produce an output that is translated into longitudinal movement of the extendable rod.

22. The growing rod of claim 21, wherein the magnet includes at least two polls, and wherein the extendable rod is moved relative to the fixed rod along the longitudinal axis by passing a magnetic field in proximity to the growing rod to cause the magnet to rotate about the longitudinal axis.

23. The growing rod of claim 21, wherein the gear reduction mechanism further comprises:

a gear housing;

a carrier gear driven by a ratchet arm that is pivotally mounted within the gear housing; and

a pawl that is mounted within the ratchet arm,

wherein movement of the ratchet arm drives the pawl to engage pawl teeth with external gear teeth of the carrier gear, and wherein internal gear teeth of the carrier gear mesh with threads on the extendable rod to cause the extendable rod to translatable relative to the fixed rod along the longitudinal axis.

24. The growing rod of claim 23, further comprising a locking mechanism that engages the pawl, wherein a position of the locking mechanism within the pawl blocks a first rotational direction of the carrier gear and allows a second rotational direction of the carrier gear.

25. The growing rod of claim 24, wherein the first rotational direction causes the extendable rod to translate in a direction away from the fixed rod along the longitudinal direction.

26. The growing rod of claim 23, wherein an second rotational direction causes the extendable rod to translate in a direction toward the fixed rod along the longitudinal direction.

27. The growing rod of claim 23, wherein the gear reduction mechanism further, comprises

a gear housing having internal gear teeth;

a gear wheel having external gear teeth;

a driver wheel having diver pins fixed thereto that are fitted within the gear wheel, the driver wheel including a threaded shaft; and

a carrier that mates with the threaded shaft and to extendable rod by torque pins.

28. The growing rod of claim 27, wherein the external gear teeth are mismatched with the internal gear teeth such that the gear wheel rotates less than a full rotation for each full rotation of the magnet.

29. The growing rod of claim 27, further comprising a slider that is fixed to housing, the slider including a pair of slots that receive the torque pins to limit rotational movement of the extendable rod.

30. The growing rod of claim 21, wherein the gear reduction mechanism further comprises:

an gear housing having internal gear teeth;

a gear wheel having external gear teeth;

a driver wheel having diver pins fixed thereto that are fitted within the gear wheel, the driver wheel including a threaded shaft; and

a carrier that mates with the threaded shaft and to extendable rod by a keyway.

31. The growing rod of claim 30, wherein the interaction of the carrier and the extendable rod through the keyway limits rotational movement of the extendable rod.

32. An expandable spinal growing rod, comprising:

a first rod that is fixedly attached to a housing at a first end of the housing;

a second rod that extends from a second end of the housing and that moves along a longitudinal axis; and

a magnet within the housing; and

a gear mechanism that is engaged by the magnet,

wherein input rotational movement of magnet drives the gear mechanism, and wherein rotational movement of the gear mechanism is translated into longitudinal movement of the second rod relative to the housing.

33. The spinal growing rod of claim 32, wherein the second rod moves along the longitudinal axis substantially without rotation relative to the first rod.

34. The spinal growing rod of claim 32, wherein the gear mechanism comprises a gear reduction mechanism that reduces the input rotational movement of magnet with respect to an output of the gear mechanism.

35. The spinal growing rod of claim 32, wherein the gear mechanism rotates bi-directionally such that second rod is moveable relative to the first rod along the longitudinal axis in a first direction away from the first rod or in a second direction toward the first rod.

36. The spinal growing rod of claim 35, further comprising a locking mechanism that engages within gear mechanism to block rotation of the gear mechanism such that the second rod moves in the first direction or the second direction in accordance with a position of the locking mechanism.

37. The spinal growing rod of claim 32, wherein the input rotation movement of the gear mechanism is caused by passing a magnetic field in proximity to the magnet of the spinal growing rod.