PERCUTANEOUS SYSTEM FOR DYNAMIC SPINAL STABILIZATION

• US 20080051787A1
• Filed: 06/29/2007
• Published: 02/28/2008
• Est. Priority Date: 08/22/2006
• Status: Active Grant

• Current Assignee: Neuropro Technologies Inc.
• Original Assignee: Neuropro Technologies Inc.
• Inventors: MITCHELL, Stuart B., MIRISOLA, Jeffrey R., GREEN, John I., BAKER, Daniel R., REMINGTON, Benjamin J.
• Granted Patent: US 9,526,525 B2
• Time in Patent Office: Days
• US Class Current: 606/61
• CPC Class Codes: A61B 17/70 Spinal positioners or stabilisers ; Bone stabilisers comprising fluid filler in an implant
• 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 17/7019 Longitudinal elements having flexible parts, or parts connected together, such that after implantation the elements can move relative to each other
• CPC Class Codes: A61B 17/7023 with a pivot joint
• CPC Class Codes: A61B 17/7026 with a part that is flexible due to its form
• CPC Class Codes: A61B 17/7031 made wholly or partly of flexible material
• CPC Class Codes: A61B 17/7032 Screws or hooks with U-shaped head or back through which longitudinal rods pass
• CPC Class Codes: A61B 17/7074 Tools specially adapted for spinal fixation operations other than for bone removal or filler handling A61B17/7062, A61B17/808, A61B17/8858 take precedence; for spinal image producing devices A61B90/36, A61B34/20; markers A61B90/39
• CPC Class Codes: A61B 17/708 with tubular extensions coaxially mounted on the bone anchors
• CPC Class Codes: A61B 17/7083 Tools for guidance or insertion of tethers, rod-to-anchor connectors, rod-to-rod connectors, or longitudinal elements
• CPC Class Codes: A61B 17/8869 Tensioning devices

Abstract

A minimally invasive, percutaneous system that allows for dynamic stabilization of the spine is provided, together with methods of using the system. The system comprises a first bone anchoring member that is anchored in a first vertebra, and a second bone anchoring member that is anchored in a second, adjacent, vertebra. The first and second bone anchoring members include a first head portion and second head portion, respectively, that are designed to hold first and second ends of a flexible, elongated member, or cord. In certain embodiments, the cord is provided with a stiffened, relatively inflexible, end portion that is fixedly attached to the cord and that facilitates threading of the cord through the first and second head portions.

Claims

1. A system for stabilizing at least two vertebrae, comprising:

(a) a flexible, elongated member having a length sufficient to extend between the two bones;

(b) a generally cylindrical spacer having an aperture extending along a longitudinal axis thereof, wherein the aperture is sized to receive a portion of the elongated member;

(c) a first bone anchoring member comprising a first head portion and a first bone anchoring portion, wherein the first head portion is provided with a generally transverse aperture sized to receive a first portion of the elongated member and having a diameter that is smaller than an outer diameter of the spacer element;

(d) a second bone anchoring member comprising a second head portion and a second bone anchoring portion, wherein the second head portion is provided with a generally U-shaped recess that extends through the second head portion in a generally transverse direction and is sized to receive a second portion of the elongated member, and wherein the spacer element is able to pass through the U-shaped recess;

(e) a first locking member for retaining the first portion of the elongated member in the first head portion; and

(f) a second locking member for retaining the second portion of the elongated member in the second head portion,

whereby, once the first and second portions of the elongated member are positioned in the first and second head portions, the spacer member can be threaded along the elongated member and through the second head portion until it abuts a surface of the first head portion.

2. The system of claim 1, wherein the second head portion comprises:

(a) a first rotatable member positioned in the U-shaped recess and having a first generally vertical face; and

(b) a second rotatable member positioned in the U-shaped recess and having a second generally vertical face that opposes and is spaced-part from the first face to form a passageway for receiving the spacer mounted on a portion of the elongated member,

wherein distal ends of first and second faces may be rotated proximally towards each other whereby the spacer is pushed along the elongated member.

3. The system of claim 2, further comprising a locking mechanism for retaining first and second rotatable members in a locked position following positioning of the spacer between the first and second head portions.

4. The system of claim 1, wherein the elongated member is provided with a stiffened region at, or in proximity to, its distal end.

5. The system of claim 1, wherein the elongated member is cannulated, whereby the elongated member may be threaded onto a guidewire to facilitate placement of the elongated member in the first and second head portions.

6. The system of claim 1, wherein the elongated member is provided with a protrusion at, or in proximity to, its distal end, whereby the protrusion may be grasped by an instrument and pulled through the first and second head portions.

7. The system of claim 1, wherein the elongated member is constructed of a material whose tension varies with temperature.

8. The system of claim 1, wherein the elongated member is in the form of a braided metal cord.

9. The system of claim 1, wherein the elongated member is provided with a region having an enlarged diameter, wherein the enlarged diameter region is sized to be received and retained in the transverse aperture of the second head portion.

10. The system of claim 1, wherein the spacer is sized to extend between the first and second head portions when the first and second bone anchoring members are positioned in the bones.

11. The system of claim 1, wherein the spacer is formed of a material whose stiffness increases as the spacer warms from room temperature to body temperature.

12. The system of claim 1, wherein at least one of the first and second bone anchoring members is a polyaxial pedicle screw.

13. The system of claim 1, wherein at least one of the first and second bone anchoring portions is cannulated.

14. The system of claim 1, wherein at least one of the first and second locking members is a set screw which is able to engage a threaded portion provided on an inner surface of an aperture provided in a top surface of the first or second head portion.

15. The system of claim 1, further comprising:

(a) a third bone anchoring member having a third bone anchoring portion for placement in a third bone; and

(b) a second generally cylindrical spacer sized to extend between the second and third bone anchoring members,

wherein the first and second spacers have different flexibilities.

16. The system of claim 15, wherein one of the first and second spacers has a flexibility that permits movement between two adjacent bones and the other of the first and second spacers has a flexibility that restricts movement between two adjacent bones to a level that is sufficient to permit fusion of two adjacent bones.

17. The system of claim 1, further comprising a locking ring having a transverse aperture that is sized to receive a portion of the elongated member, wherein the diameter of an outer surface of the locking ring is larger than that of an outer surface of the spacer, and wherein the locking ring is sized to be retained in the transverse aperture of the second head portion, whereby, following positioning of the spacer on the elongated member between the first and second head portions and positioning of the locking ring on the elongated member proximal to the spacer, the locking ring prevents movement of the spacer in a proximal direction.

32. The system of claim 1, further comprising a locking ring having a transverse aperture that is sized to receive a portion of the elongated member, wherein the diameter of an outer surface of the locking ring is larger than that of an outer surface of the spacer, and wherein the locking ring is sized to be retained in the transverse aperture of the second head portion, whereby, following positioning of the spacer on the elongated member between the first and second head portions and positioning of the locking ring on the elongated member proximal to the spacer, the locking ring prevents movement of the spacer in a proximal direction.

18. A minimally invasive system for stabilizing at least two vertebrae, comprising:

(a) a flexible, elongated member having a length sufficient to extend between the two bones;

(b) a first generally cylindrical spacer having an aperture extending along a longitudinal axis, wherein the aperture is sized to receive a portion of the elongated member;

(c) a first bone anchoring member comprising a first head portion and a first bone anchoring portion, wherein the first head portion is provided with a generally transverse aperture sized to receive a first portion of the elongated member and having a diameter that is smaller than a diameter of an outer surface of the spacer element;

(d) a second bone anchoring member comprising a second head portion and a second bone anchoring portion, wherein the second head portion is provided with a generally transverse aperture for receiving a second portion of the elongated member and having a diameter that is larger than a diameter of an outer surface of the spacer element, whereby the spacer element is able to pass through the aperture on the second head portion;

(e) a first locking member for retaining the first portion of the elongated member in the first head portion; and

(f) a second locking member for retaining the second portion of the elongated member in the second head portion,

whereby, once the first and second portions of the elongated member are positioned in the first and second head portions, the spacer member can be threaded along the elongated member and through the second head portion until it abuts a surface of the first head portion.

19. The system of claim 18, wherein the elongated member is provided with a stiffened region at, or in proximity to, its distal end.

20. The system of claim 18, wherein the elongated member is cannulated, whereby the elongated member may be threaded onto a guidewire to facilitate placement of the elongated member in the first and second head portions.

21. The system of claim 18, wherein the elongated member is provided with a protrusion at, or in proximity to, its distal end, whereby the protrusion may be grasped by an instrument and pulled through the first and second head portions.

22. The system of claim 18, wherein the elongated member is constructed of a material whose tension varies with temperature, and the tension of the elongated member decreases as the elongated member warms from room to body temperature.

23. The system of claim 18, wherein the elongated member is in the form of a braided metal cord.

24. The system of claim 18, wherein the elongated member is provided with a region having an enlarged diameter, wherein the enlarged diameter region is sized to be received and retained in the transverse aperture of the second head portion.

25. The system of claim 18, wherein the spacer is sized to extend between the first and second head portions when the first and second bone anchoring members are positioned in the bones.

26. The system of claim 18, wherein the spacer is formed of a material whose stiffness increases as the spacer warms from room temperature to body temperature.

27. The system of claim 18, wherein at least one of the first and second bone anchoring members is a polyaxial pedicle screw.

28. The system of claim 18, wherein at least one of the first and second bone anchoring portions is cannulated.

29. The system of claim 18, wherein at least one of the first and second locking members is a set screw which is able to engage a threaded portion provided on an inner surface of an aperture provided in a top surface of the first or second head portion.

30. The system of claim 18, further comprising:

(a) a third bone anchoring member having a third bone anchoring portion for placement in a third bone; and

(b) a second generally cylindrical spacer sized to extend between the second and third bone anchoring members,

wherein the first and second spacers have different flexibilities.

31. The system of claim 30, wherein one of the first and second spacers has a flexibility that permits movement between two adjacent bones and the other of the first and second spacers has a flexibility that restricts movement between two adjacent bones to a level that is sufficient to permit fusion of two adjacent bones.

33. A tool for grasping and retaining a region of a flexible elongated spinal stabilization member during implantation of the spinal stabilization member in a patient, comprising:

(a) a first generally U-shaped elongated member; and

(b) a second generally U-shaped elongated member having an outer radius that is smaller than an inner radius of the first elongated member,

wherein the inner surface of the first elongated member is provided with at least one first engagement member that slidably engages at least one second engagement member provided on an outer surface of the second elongated member, and wherein, following positioning of the region of the spinal stabilization member in at least a portion of the first elongated member, second elongated member may be advanced in first elongated member with the first engagement member engaging the second engagement member, whereby distal ends of the first and second engagement members are brought into proximity with each other thereby grasping the spinal stabilization member.

34. The tool of claim 33, wherein

(a) the at least one first engagement member is provided as an inward protrusion that extends along, but not parallel to, a longitudinal axis of the first elongated member whereby the first engagement member is closer to an outer edge of first elongated member in an upper region of the first elongated member than in a lower region of the first elongated member;

and

(b) the at least one second engagement member is provided as an outward protrusion that extends along, but not parallel to, a longitudinal axis of the second elongated member whereby the second engagement member is closer to an outer edge of the second elongated member in a lower region of the second elongated member than in an upper region of the second elongated member.

35. The tool of claim 33, wherein the inner surface of the first elongated member is provided with two opposing first engagement members and the outer surface of the second elongated member is provided with two opposing second engagement members.

36. The tool of claim 35, wherein the inner surfaces of the first and second elongated member are roughened whereby the ability of the first and second elongated members to grasp the spinal stabilization member is increased.

37. A tool set for applying tension to a flexible elongated spinal stabilization member during implantation of the spinal stabilization member in a patient, comprising:

(a) an elongated guide tube having an open upper end and an open lower end, the tube being sized to fit over at least a head portion of a bone anchoring member;

(b) a retaining member that is positionable in the guide tube to grasp and retain a proximal region of the spinal stabilization member following positioning of a distal region of the spinal stabilization member in the bone anchoring member, wherein the retaining member comprises;

(i) a first generally U-shaped elongated member; and

(ii) a second generally U-shaped elongated member having an outer radius that is smaller than an inner radius of the first elongated member,

wherein the inner surface of the first elongated member is provided with at least one first engagement member that slidably engages at least one second engagement member provided on an outer surface of the second elongated member, and wherein, following positioning of the proximal region of the spinal stabilization member in at least a portion of the first elongated member, second elongated member may be advanced in first elongated member with the first engagement member engaging the second engagement member, whereby distal ends of the first and second engagement members are brought into proximity with each other thereby grasping the proximal region of the spinal stabilization member; and

(c) a rigid elongated tensioning member that is positionable in the guide tube to engage, and apply tension to, a region of the spinal stabilization member located between the proximal and distal regions.

38. The tool set of claim 37, wherein the first and second engagement members are in the form of elongated protrusions that extend along, but not parallel to, a longitudinal axis of the first and second elongated members.

39. The tool set of claim 37, wherein the tensioning member is in the form of a rod having an enlarged distal region.

40. The tool set of claim 37, further comprising a handle that can be grasped by the hand of a user, the handle comprising a first handle member attached to the first elongated member that is able to engage a second handle member attached to the second elongated member.

41. The tool set of claim 40, further comprising a first indicator provided on the first handle member and a second indicator on the second handle member, wherein correct positioning of the first and second elongated members is shown by mating of the first and second indicators.

42. The tool set of claim 40, wherein the tensioning member is movably connected to the handle.