Implant assembly and method for use in an internal structure stabilization system

• US 20060036244A1
• Filed: 11/16/2004
• Published: 02/16/2006
• Est. Priority Date: 10/21/2003
• Status: Active Grant

• Current Assignee: Theken Spine LLC (Orthofix Medical Inc.)
• Original Assignee: Innovative Spinal Technologies, Inc. (Integra LifeSciences Holdings Corporation)
• Inventors: Colleran, Dennis, Spitler, James, Schorer, Scott
• Granted Patent: US 7,618,442 B2
• Time in Patent Office: Days
• US Class Current: 74/1.R
• CPC Class Codes: A61B 17/1604 Chisels; Rongeurs; Punches; Stamps
• CPC Class Codes: A61B 17/1655 for tapping
• CPC Class Codes: A61B 17/1757 for the spine
• CPC Class Codes: A61B 17/320016 Endoscopic cutting instruments, e.g. arthroscopes, resectoscopes A61B10/0233, A61B17/29, A61B17/3207 take precedence
• CPC Class Codes: A61B 17/3417 Details of tips or shafts, e.g. grooves, expandable, bendable; Multiple coaxial sliding cannulas, e.g. for dilating syringe needles A61M5/32; dilators A61M29/00
• CPC Class Codes: A61B 17/3421 Cannulas
• CPC Class Codes: A61B 17/3468 for implanting or removing devices, e.g. prostheses, implants, seeds, wires devices for implanting seeds A61M37/0069
• CPC Class Codes: A61B 17/7002 Longitudinal elements, e.g. rods
• CPC Class Codes: A61B 17/7005 Parts of the longitudinal elements, e.g. their ends, being specially adapted to fit in the screw or hook heads
• CPC Class Codes: A61B 17/701 Longitudinal elements with a non-circular, e.g. rectangular, cross-section A61B17/7005, A61B17/7007 take precedence
• CPC Class Codes: A61B 17/7011 Longitudinal element being non-straight, e.g. curved, angled or branched adjustable length longitudinal elements A61B17/7014; A61B17/7019 takes precedence, e.g. coil springs
• CPC Class Codes: A61B 17/7032 Screws or hooks with U-shaped head or back through which longitudinal rods pass
• CPC Class Codes: A61B 17/7037 wherein pivoting is blocked when the rod is clamped
• CPC Class Codes: A61B 17/7038 to a different extent in different directions, e.g. within one plane only
• CPC Class Codes: A61B 17/704 the longitudinal element passing through a ball-joint in the screw head
• CPC Class Codes: A61B 17/7082 for driving, i.e. rotating, screws or screw parts specially adapted for spinal fixation, e.g. for driving polyaxial or tulip-headed screws driving other bone screws A61B17/8875
• CPC Class Codes: A61B 17/7085 for insertion of a longitudinal element down one or more hollow screw or hook extensions, i.e. at least a part of the element within an extension has a component of movement parallel to the extension's axis
• CPC Class Codes: A61B 17/7091 for applying, tightening or removing longitudinal element-to-bone anchor locking elements, e.g. caps, set screws, nuts or wedges
• CPC Class Codes: A61B 2017/320044 Blunt dissectors blunt suture needles A61B2017/06085
• CPC Class Codes: A61B 2090/061 for measuring dimensions, e.g. length
• CPC Class Codes: A61B 2090/067 : for measuring angles
• CPC Class Codes: A61B 5/103 : Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes A61B5/08 takes precedence; measuring aids for tailors A41H1/00; measuring instruments specially adapted for dentistry A61C19/04
• CPC Class Codes: A61B 5/107 : Measuring physical dimensions, e.g. size of the entire body or parts thereof
• CPC Class Codes: A61B 5/4504 : Bones A61B5/4547 takes precedence
• CPC Class Codes: A61B 5/6878 : Bone
• CPC Class Codes: A61B 5/6882 : Anchoring means
• CPC Class Codes: Y10T 74/22 : Miscellaneous

Abstract

A stabilization assembly is described that stabilizes bony structures such as vertebrae. The stabilization assembly is partially formed by a poly-axial assembly which includes an anchor connected to a poly axial connector assembly head, where the poly-axial connector-assembly head includes a slide ring mounted in the head and a connector mounted in the slide ring. The slide ring allows the connector to move between an upright and a horizontal position relative to the poly-axial connector-assembly head. In the upright position the connector engages with a drive mechanism on the anchor for inserting the anchor into a pedicle. In the horizontal position the connector can engage a poly-axial connector capturing assembly which is the second piece included in the stabilization assembly. An end of the connector engages with a poly-axial connector-capturing head which is connected another anchor mounted in a second pedicle. Once the connector is captured by the poly-axial connector-capturing assembly, the stabilization system is made rigid by installing locking caps in the poly-axial heads.

Claims

1. An assembly for use in spinal stabilization procedures, comprising:

a first bone anchor assembly comprising;

a first anchor a first poly-axial head mated with said anchor such that said anchor is movable in relation to said poly-axial head, said first poly-axial head including a cavity; and

a second bone anchor assembly comprising;

a second anchor;

a second poly axial head mated with said anchor such that said anchor is movable in relation to said poly-axial head;

a slide ring rotatably mated in said second poly-axial head;

a connector slideably mated in said slide ring along a distal end, and having a proximal end having an enlarged portion;

wherein said connector is movable from a first position axially inline with said second bone anchor to a second position wherein said enlarged portion of said connector rests in said cavity of said first poly axial head, and wherein said first position is used to implant said first bone anchor assembly, and said second position used to hold said assembly in a fixed orientation.

2. The assembly of claim 1 further comprising a snap ring in said first poly-axial head, said snap ring holding said enlarged portion of said connector in said cavity.

3. The assembly of claim 1 further comprising locking caps inserted into said first and said second poly-axial heads, wherein said locking caps act to lock said elements of said bone anchor assembly into a fixed orientation.

4. The assembly of claim 2 wherein said locking caps comprise:

a locking ring insertable into said second poly-axial head and operable to hold said slide ring, said first poly-axial head and said first anchor in a fixed orientation; and

a compression cap insertable into said locking ring and operable to hold said connector in a fixed orientation with said slide ring.

5. The assembly of claim 1 further comprising an extension removably attached to said first poly-axial head assembly, said extension allowing access to said first bone anchor assembly after implantation.

6. The assembly of claim 5 wherein said extension comprises:

a tubular body having an attachment mechanism for attaching to said first poly-axial head; and

a locking mechanism for temporarily locking said extension with said first poly-axial head.

7. The assembly of claim 6 wherein said locking mechanism is a twist ring and a slider attached to said tubular body, said twist ring twistable to cause said slider to move between a first and second position, said first position temporarily locking said extension to said first poly-axial head, said second position allowing said extension to be disengaged from said poly axial head.

8. The assembly of claim 1 wherein said first anchor includes an off-axis guide from a tip of said first anchor out a side of said first anchor, said off axis guide allowing said first anchor to be guided down a guide wire.

9. The assembly of claim 1 wherein said connector includes a drive mechanism mated to a drive mechanism of said second anchor when said connector is in said first position, said connector operable in said first position to transfer torque from a tool to said second anchor.

10. The assembly of claim 1 wherein said connector includes an engagement mechanism in said spherical portion, said engagement mechanism for engaging with a connector transfer tool.

11. A method for assembling an assembly for stabilizing bony structures comprising:

attaching a first bone anchor assembly to an extension, said first bone anchor assembly including a first anchor, a first poly-axial head movably connected to said first anchor; and

inserting said first bone anchor assembly into a first bony structure along a guide wire, said guide wire passing through an off-axis guide in said first anchor.

12. The method of claim 11 further comprising:

driving said first bone anchor into said first bony structure by inserting a drive mechanism into said extension, said drive mechanism engaging with a drive mechanism on said first anchor.

13. The method of claim 12 further comprising:

measuring a distance between said first bone anchor assembly and a second guide wire inserted into a second bony structure; and

choosing a second bone anchor assembly based on said measurement, said second bone anchor assembly including second anchor, a second poly-axial head movably connected to said second anchor, a slide ring rotatably connected to said second poly-axial head, and a connector slideably mounted in said slide ring.

14. The method of claim 13 further comprising:

attaching said second bone anchor assembly to a second extension;

inserting said second bone anchor assembly into said second bony structure along said second guide wire, said second guide wire passing through an off-axis guide in said second anchor; and

driving said second bone anchor into said second bony structure by inserting said drive mechanism into said second extension, said drive mechanism engaging with a proximal end of said connector, a distal end of said connector engaging with a drive mechanism on said second anchor.

15. The method of claim 14 further comprising:

rotating said connector from a first position axially inline with said second bone anchor to a second position, said second position corresponding to a spherical portion of a proximal end of said connector being held in a cavity of said first poly-axial head by a clip ring in said first poly axial head.

16. The method of claim 15 further comprising:

inserting locking caps into said first and said second poly-axial heads, said locking caps holding said assembly in a fixed position.

17. The method of claim 16 further comprising:

removing said extension and said second extension from said first and second bone anchor assemblies.

18. An assembly for use in spinal stabilization procedures, said assembly comprising:

a connector, at least a portion of an end of said connector having surfaces therealong, said surfaces extending along the longitudinal axis of said connector; and

a bracket having surfaces positioned in contact with said surfaces of said connector, and allowing said connector to move laterally with respect to said bracket.

19. The assembly of claim 18 wherein said bracket further comprises tabs protruding therefrom attaching said bracket to a poly-axial head, and wherein said bracket surfaces preventing said bracket from disengaging with said connector and said tabs allowing said distal end of said connector to become selectively disengaged from an anchor while preventing said bracket from disengaging from said poly-axial head.

20. The assembly of claim 19 wherein said tabs allow said connector to rotate from an in-line orientation with respect to the longitudinal axis of a bone anchor to an orientation substantially perpendicular to said longitudinal axis, said bracket flats facilitating said rotation.

21. A connector for use in spinal stabilization procedures, said connector for positioning between pedicles of a spine, said connector comprising:

a distal end adapted for mating with a proximal end of a pedicle anchor for driving said anchor into said pedicle by the application of force on the proximal end of said connector.

22. The connector of claim 21 further comprising a proximal end for mating with a torque transfer device for driving said bone into said pedicle, said proximal end also having at least one hole for receiving locking tines from a rotational tool applied in-line with said connector, said hole surrounded by at least one ramp surface for facilitating said receiving of said tines and at least one surface for preventing received ones of said tines from disengaging with said tool until said connector has been rotated approximately 90 degrees from said in-line position.

23. A bracket for connecting to a poly-axial head, comprising:

flats for mating with flats along a distal portion of said connector, said flats preventing said bracket from disengaging with said connector while still allowing said connector to be laterally adjusted with respect to said bracket; and

tabs protruding outward from said bracket, said tabs for attaching said bracket to a poly-axial head, said tabs allowing said bracket to rotate relative to said poly-axial head.

24. The bracket of claim 23 wherein said bracket allows said connector to become selectively disengaged from mating with said pedicle anchor while preventing said bracket from disengaging from said poly-axial head.

25. A poly-axial head for use with a pedicle screw, said head comprising:

a distal end for axially connecting to a proximal end of a pedicle anchor embeddable in a first pedicle;

a cavity defined within said head for receiving the proximal end of a connector;

a groove positioned at least around a portion of the interior walls of said cavity, said groove positioned near the proximal end of said cavity, and

a snap ring partially within said groove, said snap ring having an at-rest inner radius slightly smaller than said radius of said connector proximal end and having an expansion inner radius slightly larger than said connector proximal end such that when said connector proximal end is pushed against said ring said radius expands into said groove to its larger radius so as to allow said connector proximal end to pass fully into said cavity.

26. The poly-axial head of claim 25 wherein the expansion and contraction of said snap ring provides tactile feedback to a user applying force to said connector proximal end.

27. The poly-axial head of claim 25 wherein said expansion and contraction of said snap ring provides audible feedback to a user applying force to said connector proximal end

28. The poly-axial head of claim 25 wherein said ring resuming its smaller radius after said connector has passed by serves to prevent said connector end from coming out of said head cavity.

29. The poly-axial head of claim 25 further comprising:

means in said head to prevent said ring from rotating.

30. The poly-axial head of claim 25 wherein said head is open on one wall thereof to allow said connector shank to pass into said cavity, said shank being partially in and partially out of said cavity, said head being prevented from blocking said open area.

31. The poly-axial head of claim 30 wherein said opening in said wall has a radius large enough to allow said shank to pass therethrough and small enough to prevent said connector proximal end from passing therethrough.

32. A poly-axial head for use with a pedicle screw, said head comprising:

a distal end for axially connecting to a proximal end of a pedicle anchor, said distal end having a ploy-axial receptacle for receiving therein the poly-axial head portion of said pedicle screw, said receptacle comprising;

threads for allowing said receptacle to thread onto and past mating threads positioned around said head portion of said pedicle screw;

said poly-axial head further comprising;

a cavity defined within side walls of said head for mating with the distal end of a connector, said connector rotatable from a position in-line with the longitudinal axis of a mated pedicle screw to a horizontal position such that the shank of said connector spans from said mated pedicle to a second pedicle, said connector proximal end, said cavity comprising;

means for allowing said connector to temporarily mate with a drive mechanism of a driver for the transfer of torque to said anchor.

33. The poly-axial head of claim 32 wherein said temporary mating means comprises:

a pair of top and bottom bounded openings, each said bounded opening in an opposing side wall of said head, said openings being elongated along the longitudinal axis of said cavity, said slots capturing tabs protruding from a bracket positioned around the distal shank portion of said connector while allowing said bracket to slide longitudinally therein.

34. The poly-axial head of claim 33 wherein said bounding of said openings controls the longitudinal distance of said slide.

35. The poly-axial head of claim 32 wherein said sidewalls comprising:

a pair of opposing openings therein, said openings unbounded on their proximal end so as to allow said connector to rotate to said horizontal position thereby extending out of the confines of said cavity.

36. The poly-axial head of claim 32 wherein said sidewalls have a proximal end adapted for temporarily being mated to an extension, said extension being tubular and encompassing said connector when said connector is in-line with said pedicle screw.

37. The poly-axial head of claim 36 wherein said mating comprises means for rotating a distal portion of said extension into locking position at said proximal end of said sidewalls.

38. The poly-axial head of claim 37 wherein said proximal end of said sidewall further comprises at least one slot for receiving a locking device extended from said extension, said device operable for preventing said extension from rotating with respect to said head.

39. A locking cap for locking a bone anchor assembly, the bone anchor assembly including a poly-axial head, an anchor connected to said poly axial head, and a connector slidably engaged with said poly-axial head, the locking cap comprising:

a locking ring having an outer engagement mechanism for mating with said poly-axial head, and an inner engagement mechanism, said locking ring operable to lock said poly-axial head and said anchor into a rigid relationship when mated with said poly-axial head, while allowing said connector to slide within said poly-axial head; and

a compression cap having an engagement mechanism for mating with said inner engagement mechanism of said locking ring, said compression cap compressing on said connector when said compression cap is engaged into said locking ring, thereby preventing said connector from sliding in said poly-axial head.

40. The locking cap of claims 39 wherein said bone anchor assembly further comprises a slide ring rotatably mounted in said poly axial head, said connector mounted in said slide ring, wherein said slide ring allows said connector to slidably move relative to said poly axial head, and wherein said locking ring compresses on said slide ring when said locking ring is engaged into said poly-axial head.

41. The locking cap of claim 39 wherein said outer engagement mechanism and said inner engagement mechanism are threads.

42. The locking cap of claim 39 wherein when engaged, a surface on said locking ring engages a first surface on said slide ring causing a second surface on said slide ring to engage with a surface on said anchor, and also causing at least a third surface of said slide ring to engage with a surface of said poly-axial head, thereby causing the locking of said poly-axial head and said anchor.

43. The locking cap of claim 39 wherein when engaged, a surface of said compression cap engages a first surface of said connector causing a second surface of said connector to engage with a surface of said slide ring, thereby preventing said connector from sliding in said slide ring.

44. The locking cap of claim 39 wherein the locking ring includes a drive mechanism for receiving a tool, said tool engaging said locking ring with said poly-axial head.

45. The locking cap of claim 39 wherein the compression cap includes a drive mechanism for receiving a tool, said tool engaging said compression cap with said locking ring.

46. The locking cap of claim 39 wherein after said locking ring is engaged in said poly-axial head, said connector is positioned in said sliding ring, and wherein said compression cap is engaged with said locking ring after said connector has been positioned.

47. A method of locking a bone anchor assembly, the bone anchor assembly including a poly-axial head, an anchor connected to said poly axial head, a slide ring rotatably mounted in said poly axial head, and a connector slidably engaged in said poly-axial head, the method comprising:

inserting a locking ring into said poly-axial head, said locking ring forcing said poly-axial head and said anchor into a fixed, rigid position;

positioning said connector in said slide ring; and

inserting a compression cap into said locking ring, said compression cap holding said connector in said position relative to said poly-axial head.

48. The method of claim 47 wherein inserting said locking ring comprises screwing said locking ring into said poly-axial head.

49. The method of claim 48 wherein screwing said locking cap is accomplished using dovetail threads.

50. The method of claim 47 wherein inserting said compression cap comprises screwing said compression cap into said locking ring.

51. The method of claim 47 wherein said bone anchor assembly further includes a slide ring mounted in said poly-axial head, said connector slidably mounted in said slide ring.

52. The method of claim 51 wherein forcing said poly-axial head and said anchor into a fixed, rigid position is accomplished by a surface on said locking ring engaging a first surface on said slide ring causing a second surface on said slide ring to engage with a surface on said anchor, and also causing at least a third surface of said slide ring to engage with a surface of said poly-axial head, thereby causing the locking of said poly-axial head and said anchor.

53. The method of claim 51 wherein holding said connector in said position in said slide ring is accomplished by a surface of said compression cap engaging a first surface of said connector causing a second surface of said connector to engage with a surface of said slide ring, thereby preventing said connector from sliding in said slide ring.