Spine microsurgery techniques, training aids and implants

• US 20060085068A1
• Filed: 10/18/2004
• Published: 04/20/2006
• Est. Priority Date: 10/18/2004
• Status: Active Grant

• Current Assignee: Richard J. Barry
• Original Assignee: Richard J. Barry
• Inventors: Barry, Richard J.
• Granted Patent: US 7,452,369 B2
• Time in Patent Office: Days
• US Class Current: 623/17.110
• CPC Class Codes: A61B 17/1615 Drill bits, i.e. rotating tools extending from a handpiece to contact the worked material
• CPC Class Codes: A61B 17/1637 Hollow drills or saws producing a curved cut, e.g. cylindrical A61B10/025, A61B17/1695 take precedence
• CPC Class Codes: A61B 17/1671 for the spine
• CPC Class Codes: A61B 17/7064 Devices acting on, attached to, or simulating the effect of, vertebral facets; Tools therefor
• CPC Class Codes: A61B 17/92 Impactors or extractors, e.g. for removing intramedullary devices insertion or extraction of artificial joints A61F2/4603
• CPC Class Codes: A61B 2090/033 Abutting means, stops, e.g. abutting on tissue or skin
• CPC Class Codes: A61B 2090/3916 Bone tissue
• CPC Class Codes: A61F 2/4405 for apophyseal or facet joints, i.e. between adjacent spinous or transverse processes devices implanted between spinous or transverse processes A61B17/7062
• CPC Class Codes: A61F 2/4455 for the fusion of spinal bodies, e.g. intervertebral fusion of adjacent spinal bodies, e.g. fusion cages intervertebral discs A61F2/442
• CPC Class Codes: A61F 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2002/30062 (bio)absorbable, biodegradable, bioerodable, (bio)resorbable, resorptive
• CPC Class Codes: A61F 2002/30171 rosette- or star-shaped
• CPC Class Codes: A61F 2002/302 toroidal, e.g. rings
• CPC Class Codes: A61F 2002/3021 frustoconical
• CPC Class Codes: A61F 2002/30235 tubular, e.g. sleeves
• CPC Class Codes: A61F 2002/30593 hollow
• CPC Class Codes: A61F 2002/30616 Sets comprising a plurality of prosthetic parts of different sizes or orientations
• CPC Class Codes: A61F 2002/30769 madreporic
• CPC Class Codes: A61F 2002/30787 inclined obliquely with respect to each other
• CPC Class Codes: A61F 2002/30841 Sharp anchoring protrusions for impaction into the bone, e.g. sharp pins, spikes
• CPC Class Codes: A61F 2002/30884 : Fins or wings, e.g. longitudinal wings for preventing rotation within the bone cavity
• CPC Class Codes: A61F 2002/30968 : Sintering
• CPC Class Codes: A61F 2002/4627 : with linear motion along or rotating motion about the instrument axis or the implantation direction, e.g. telescopic, along a guiding rod, screwing inside the instrument
• CPC Class Codes: A61F 2210/0004 : bioabsorbable
• CPC Class Codes: A61F 2230/005 : Rosette-shaped, e.g. star-shaped
• CPC Class Codes: A61F 2230/0065 : toroidal, e.g. ring-shaped, doughnut-shaped
• CPC Class Codes: A61F 2230/0067 : conical
• CPC Class Codes: A61F 2230/0069 : cylindrical
• CPC Class Codes: A61F 2310/00023 : Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00131 : Tantalum or Ta-based alloys
• CPC Class Codes: G09B 23/30 : Anatomical models G09B23/281 - G09B23/288 take precedence

Abstract

A minimally invasive, fluoroscopically guided system is disclosed for stabilizing the articular facet joints of adjacent vertebrae. Ring and dowel implants are disclosed for installation into the facet joint. The invention includes a novel spine surgical training aid used in the initial surgeon training process for refreshing the surgeon'"'"'s perspective of the critical three dimensional anatomy of the vertebrae. The invention also includes a surgical kit having a range of size-specific drills, inserters, impactors and custom-length long k-wires matched to the internal diameter of the instrumentation system.

Claims

1. A method for stabilizing adjacent vertebrae of the spine, the adjacent vertebrae comprising superior and inferior articular processes having opposing subchondral articular surfaces to form first and second bilateral posterior facet joints, the method comprising:

forming a path into the subchondral bone of the articular surfaces of the first facet joint; and

installing an implant into the bone path of the first facet joint;

wherein the implant is configured to immobilize the first facet joint of the articulation between the adjacent vertebrae.

2. A method as recited in claim 1, further comprising:

forming a path into the subchondral bone of the articular surfaces of the second facet joint; and

installing an implant into the bone path of the second facet joint;

wherein the implant is configured to immobilize the second facet joint of the articulation between the adjacent vertebrae.

3. A method as recited in claim 1, wherein forming a path into the subchondral bone comprises:

drilling a cylindrical bore into the subchondral articular surfaces;

wherein a portion of each subchondral articular surface is removed to form grooves defining opposite ends of the cylindrical bore.

4. A method as recited in claim 3, wherein the cylindrical bore is drilled in a path substantially parallel to the planes of the subchondral surfaces.

5. A method as recited in claim 1, wherein the method is performed percutaneously under fluoroscopic guidance.

6. A method as recited in claim 5, wherein forming a path into the subchondral bone comprises:

visualizing the planes of the subchondral surfaces of the facet joint;

determining the size of the path into the subchondral bone;

installing a blunt dilator down to an outer surface of the facet joint; and

drilling a cylindrical bore into the opposing articular processes, the blunt dilator guiding the path of the cylindrical bore.

7. A method as recited in claim 6, wherein drilling a cylindrical bore comprises advancing a hollow-core drill having an inside diameter closely matching the outside diameter of the dilator over the dilator to score kerfs into the opposing articular processes.

8. A method as recited in claim 6, wherein visualizing the planes of the subchondral surfaces of the facet joint is done fluoroscopically.

9. A method as recited in claim 8, wherein determining the size of the bone path comprises positioning a radiolucent implant guide at the facet joint.

10. A method as recited in claim 9, further comprising installing a guide wire into the facet joint.

11. A method as recited in claim 10, wherein the blunt dilator is positioned at the facet joint by advancing it over the guide wire.

12. A method as recited in claim 10, wherein a radiolucent implant guide is positioned at the facet joint to measure the size of the bone path.

13. A method as recited in claim 7, wherein the dilator is configured to limit the depth of the bored bone path.

14. A method as recited in claim 13, wherein the bone path is drilled to a depth of approximately 75% of the facet joint bone mass.

15. A method as recited in claim 3, wherein installing an implant comprises driving an oversized dowel into the scored bone path to create an interference fit with opposing first and second vertebrae to mechanically lock the articulation of the first facet joint.

16. A method as recited in claim 7, wherein installing an implant comprises driving a ring implant into the cylindrical kerfs formed in the articular processes;

the ring implant constraining motion of the facet joint through circumferential tension band effect.

60. A method as recited in claim 1, wherein the bore is drilled from a dorsal aspect of the facet joint.

61. A method as recited in claim 1, wherein the bore is drilled from a dorsal aspect of the facet joint toward a ventral aspect of the facet joint.

17. An implant for stabilizing two adjacent vertebrae of the spine, the adjacent vertebrae having superior and inferior articular processes forming first and second facet joints each having opposing subchondral articular surfaces, the implant comprising:

a dowel configured to be installed into a path bored into the bone of the opposing subchondral surfaces;

said dowel having an outer surface configured to create an interference fit between articular processes the first and second vertebrae;

wherein the implant provides a mechanical lock of the facet joint articular surfaces to resist shear forces induced on the vertebral articulations.

18. An implant as recited in claim 17, wherein the outer surface of the dowel has an outer diameter sized to create the interference fit with the opposing articular surfaces.

19. An implant as recited in claim 17, wherein the outer surface of the dowel is tapered to create the interference fit between the opposing articular surfaces, the taper emanating from a leading edge of the dowel.

20. An implant as recited in claim 17, wherein the outer surface of the dowel is roughened to create the interference fit between the opposing articular surfaces.

21. An implant as recited in claim 20, wherein the roughened external surface of the dowel comprises tantalum beads.

22. An implant as recited in claim 20, wherein the roughened external surface of the dowel is plasma sprayed with calcium hydroxyapatite crystals.

23. An implant as recited in claim 20, wherein the roughened external surface of the dowel comprises undulations.

24. An implant as recited in claim 20, wherein the roughened external surface of the dowel comprises ridges.

25. An implant as recited in claim 20, wherein the roughened external surface of the dowel is configured to interdigitate with the bone surrounding the joint surfaces to provide a mechanical interlock of the facet joint.

26. An implant as recited in claim 17, wherein the dowel is cannulated along its axis for installation into the facet joint via a guide wire.

27. An implant as recited in claim 17, wherein the outside diameter of the dowel ranges from about 6 mm to about 12 mm.

28. An implant as recited in claim 17, wherein the dowel ranges from about 4 mm to about 12 mm in length.

62. An implant as recited in claim 17, wherein the dowel is configured to be installed substantially parallel to and in between the articular processes the first and second vertebrae.

63. An implant as recited in claim 62, wherein the dowel is configured to be installed from a posterior surface of the facet joint.

29. An implant for stabilizing two adjacent vertebrae of the spine, the adjacent vertebrae having superior and inferior articular processes forming first and second facet joints each having opposing subchondral articular surfaces, the implant comprising:

a ring configured to be installed into a bone path;

the bone path comprising a cylindrical kerf bored into the opposing articular processes;

the ring having an outer surface configured to create an interference fit with the surrounding bone of the kerf;

wherein the ring constrains facet joint motion through circumferential tension band effect.

30. An implant as recited in claim 29, wherein the outer surface of the ring has an outer diameter sized to create the interference fit with the surrounding bone of the kerf.

31. An implant as recited in claim 29, wherein the outer surface of the ring has a tapered leading edge of the ring.

32. An implant as recited in claim 29, wherein the outer surface of the ring is roughened to create the interference fit with the surrounding bone of the kerf.

33. An implant as recited in claim 32, wherein the roughened external surface of the ring comprises one or more fenestrations, the fenestrations configured to promote growth of cancellous bone through and around the ring implant.

34. An implant as recited in claim 33, wherein the fenestrations comprise parallel columns running axially along the outer cylindrical surface.

35. An implant as recited in claim 33, wherein the fenestrations comprise circular holes running from the outside surface to an inside surface of the ring.

36. An implant as recited in claim 33, wherein the fenestrations have raised edges at their perimeters, the raised edges forming an interference fit with the surrounding bone of the kerf.

37. An implant as recited in claim 34, wherein the external surface comprises a plurality of raised columns extending axially between the fenestrations.

38. An implant as recited in claim 29, wherein the ring is configured for installation into the facet joint via a guide wire.

39. An implant as recited in claim 29, wherein the outside diameter of the ring ranges from about 6 mm to about 12 mm.

40. An implant as recited in claim 29, wherein the ring ranges from about 4 mm to about 12 mm in length.

64. An implant as recited in claim 29, wherein the bone path is substantially parallel to opposing subchondral articular surfaces.

65. An implant as recited in claim 29, wherein the ring is configured to be installed from a posterior surface of the facet joint.

41. A kit for preparing an implant site for percutaneously installing an implant between adjacent first and second vertebrae of a patient, the kit comprising:

a guide wire having a length configured to span to the implant site from a location exterior to the patient;

a cannulated dilator configured to be received on the guide wire such that the dilator can be positioned at the implant site by advancing it along the guide wire;

said dilator having an outer diameter correlating to a physiological relationship between the first and second vertebrae; and

a drill configured to bore a bone path at the implant site;

said drill having a hollow core with an internal diameter closely matching the outer diameter of the dilator such that the drill can be positioned at the implant site by advancing it over the dilator.

42. A kit as recited in claim 41:

wherein the dilator is configured to be positioned at the facet joint formed by the first and second vertebrae; and

wherein the drill has an outer diameter configured to bore a kerf into opposing articular processes of the facet joint.

43. A kit as recited in claim 42, wherein the drill has an outer diameter ranging from about 6 mm to about 12 mm.

44. A kit as recited in claim 42, wherein the dilator has a stop to limit the depth of the drill.

45. A kit as recited in claim 42, further comprising a cannulated impactor configured to be received on the guide wire such that the impactor may be positioned at the implant site by advancing it along the guide wire to drive the implant into the bone path.

46. A system for percutaneously installing an implant at an implant site to stabilize two adjacent first and second vertebrae of a patient, the system comprising:

a guide wire having a length configured to span to the implant site from a location exterior to the patient;

a cannulated dilator configured to be received on the guide wire such that the dilator can be positioned at the implant site by advancing it along the guide wire;

said dilator having an outer diameter correlating to a physiological relationship between the first and second vertebrae;

a drill configured to bore a bone path at the implant site, the drill having a hollow core with an internal diameter closely matching the outer diameter of the dilator such that the drill can be positioned at the implant site by advancing it over the dilator; and

an implant sized to be received into the bone path to constrain motion of the first and second adjacent vertebrae, the implant configured to be advanced to the implant site via the guide wire.

47. A system as recited in claim 46, wherein the dilator is configured to be received at a facet joint formed by the first and second vertebrae;

and

wherein the drill has an outer diameter configured to bore a kerf into opposing articular surfaces processes of the facet joint.

48. A system as recited in claim 46, wherein the drill has an outer diameter ranging from about 6 mm to about 12 mm.

49. A system as recited in claim 47, wherein the dilator has a stop to limit the depth of the drill.

50. A system as recited in claim 46, further comprising a cannulated impactor to drive the implant into the bone path, the impactor configured to be received on the guide wire such that the impactor may be positioned at the implant site by advancing it along the guide wire.

51. A system as recited in claim 46, further comprising:

a radiolucent implant guide;

wherein the implant guide is positioned at the implant site to determine the size of the implant.

52. A system as recited in claim 46, further comprising:

a radiographic overlay template;

the template configured to be placed over radiographic images of the patient to determine the size of the dilator.

53. A training apparatus for demonstrating an aspect of an image-guided spine surgery procedure, the apparatus comprising:

a support;

a simulated three-dimensional spine structure disposed on the support;

the spine structure comprising a plurality of adjacent vertebrae; and

means for demonstrating an aspect of surgical procedure on the simulated spine structure.

54. A training apparatus as recited in claim 53, further comprising:

one or more color coded anatomic regions;

the color coded region correlating to an area of interest for a step in the procedure.

55. A training apparatus as recited in claim 54, further comprising one or more color coded glass markers for reference to anatomical images on a radiographic display or image;

the colors of the markers correlating to the colors of the coded regions of the spine structure.

56. A training apparatus as recited in claim 53, further comprising:

one or more bored regions;

the bored regions defining a safe path for vertebral pedicle cannulation and instrumentation.

57. A training apparatus as recited in claim 53, wherein the bored region is color coded.

58. A method for demonstrating an aspect of an image-guided spine surgery procedure, the method comprising:

generating a three-dimensional simulation of a human spine via a computer;

said the spine comprising a plurality of adjacent vertebrae;

generating a plurality of color coded regions for demonstrating an aspect of surgical procedure on the simulated spine structure; and

outputting said three-dimensional simulated spine structure and color coded regions to a display.

59. A method as recited in claim 58, wherein the displayed simulated spine structure may be rotated to view a particular orientation of the vertebrae necessary to perform a surgical procedure.