ADJUSTABLE INTERVERTEBRAL IMPLANT

• US 20100094424A1
• Filed: 03/13/2008
• Published: 04/15/2010
• Est. Priority Date: 03/13/2007
• Status: Active Grant

• Current Assignee: Depuy Synthes Products Incorporated (Johnson & Johnson)
• Original Assignee: Depuy Synthes Products Incorporated (Johnson & Johnson)
• Inventors: Evans, David, Woodburn, William
• Granted Patent: US 8,992,617 B2
• Time in Patent Office: Days
• US Class Current: 623/17.16
• CPC Class Codes: A61F 2/44 for the spine, e.g. vertebrae, spinal discs
• CPC Class Codes: A61F 2/4465 having a circular or kidney shaped cross-section substantially perpendicular to the axis of the spine
• CPC Class Codes: A61F 2002/2835 Bone graft implants for filling a bony defect or an endoprosthesis cavity, e.g. by synthetic material or biological material
• CPC Class Codes: A61F 2002/30004 the prosthesis being made from materials having different values of a given property at different locations within the same prosthesis
• CPC Class Codes: A61F 2002/30133 kidney-shaped or bean-shaped
• CPC Class Codes: A61F 2002/302 toroidal, e.g. rings
• CPC Class Codes: A61F 2002/30235 tubular, e.g. sleeves
• CPC Class Codes: A61F 2002/30369 Limited lateral translation of the protrusion within a larger recess
• CPC Class Codes: A61F 2002/30405 made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/30495 using a locking ring
• CPC Class Codes: A61F 2002/305 Snap connection
• CPC Class Codes: A61F 2002/30507 using a threaded locking member, e.g. a locking screw or a set screw
• CPC Class Codes: A61F 2002/30517 using a locking plate
• CPC Class Codes: A61F 2002/30522 releasable, e.g. using a releasable ratchet
• CPC Class Codes: A61F 2002/3055 for adjusting length
• CPC Class Codes: A61F 2002/30565 having spring elements
• CPC Class Codes: A61F 2002/30571 Leaf springs
• CPC Class Codes: A61F 2002/30574 with an integral complete or partial collar or flange
• CPC Class Codes: A61F 2002/30593 hollow
• CPC Class Codes: A61F 2002/30601 telescopic
• CPC Class Codes: A61F 2002/30604 : modular
• CPC Class Codes: A61F 2002/30785 : parallel
• CPC Class Codes: A61F 2002/30843 : Pyramidally-shaped
• CPC Class Codes: A61F 2220/0025 : Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0033 : made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2230/0015 : Kidney-shaped, e.g. bean-shaped
• CPC Class Codes: A61F 2230/0065 : toroidal, e.g. ring-shaped, doughnut-shaped
• CPC Class Codes: A61F 2230/0069 : cylindrical
• CPC Class Codes: A61F 2250/0014 : having different values of a given property or geometrical feature, e.g. mechanical property or material property, at different locations within the same prosthesis
• CPC Class Codes: A61F 2310/00017 : Iron- or Fe-based alloys, e.g. stainless steel
• CPC Class Codes: A61F 2310/00023 : Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00179 : Ceramics or ceramic-like structures

Abstract

An expandable intervertebral implant (10) includes a first member (20), a second member (40), and a collar operatively associated with the first and second members, wherein the collar includes a threaded mechanism so that rotation of the collar causes the second member to axially move with respect to the first member. The implant includes a ratchet mechanism (50, 80) so that when at least a predetermined amount of force is applied, the second member moves with respect to the first member in an axial, ratchet-type manner. The collar preferably includes a drive ring (50) rotatably attached to the first member and a ratchet ring (50) operatively associated with the drive ring. The ratchet ring includes an inner bore having at least one corresponding ratchet thread tooth form formed thereon for engaging a ratchet thread tooth form formed on the second member.

Claims

1. An expandable intervertebral implant for implantation between first and second vertebrae, the implant comprising:

a first body member having a first end and a second end;

a second body member having a first end and a second end, the first end of the first body member being positioned proximate the first end of the second body member in a collapsed position, the second body member including at least one ratchet thread tooth form formed thereon; and

a collar operatively associated with the first and second body members, the collar including a threaded mechanism operatively engagable to the at least one ratchet thread tooth form so that rotation of the collar causes the second body member to axially move with respect to the first body member and a ratchet mechanism so that when at least a predetermined amount of force is applied axially to at least one of the first and second body members, the second body member moves with respect to the first body member in an axial ratchet-type manner.

2. The implant of claim 1, wherein the second body member is smaller than the first body member so that the second body member is received within the first body member.

3. The implant of claim 1, wherein the first body member is a substantially cylindrical member having an internal bore and the second body member is a substantially cylindrical member having an outer surface, the outer surface of the second body member being receivable within the internal bore of the first body member.

4. The implant of claim 3, wherein the outer surface of the second body member includes the ratchet thread tooth form formed thereon, the ratchet thread tooth form enabling the second body member to be rotatable with respect to the collar and enabling the second body member to ratchet with respect to the collar.

5. The implant of claim 1, wherein the collar includes a drive ring rotatably attached to the first body member, the drive ring including an inner bore for receiving the second body member and a ratchet ring operatively associated with the drive ring, the ratchet ring including an inner bore having at least one corresponding ratchet thread tooth form formed thereon for engaging the ratchet thread tooth form formed on the second body member.

6. The implant of claim 5, wherein the drive ring includes a plurality of projections for mating with a circumferential groove formed on an outer surface of the first body member.

7. The implant of claim 5, wherein the ratchet ring is coupled to the drive ring so that rotation of the drive ring causes rotation of the ratchet ring

8. The implant of claim 5, wherein the ratchet ring includes at least one slot so that the ratchet ring is radially expandable, the ratchet ring radially expanding when the second body member moves with respect to the first body member in the ratchet-type manner such that teeth of the corresponding ratchet thread tooth form are able to axially move past teeth of the ratchet thread tooth form formed on the second body member.

9. The implant of claim 5, wherein the drive ring and the ratchet ring are generally axially fixed but rotationally movable with respect to the first body member.

10. The implant of claim 1, further comprising:

a locking mechanism for fixing the position of the first body member with respect to the second body member, the locking mechanism including a plurality of set screws mounted to the collar.

11. The implant of claim 1, further comprising:

a first endplate for contacting an endplate of the first vertebra; and

a second endplate for contacting an endplate of the second vertebra, the first and second endplates are removeably coupled to the first and second body members, respectively.

12. An expandable intervertebral implant for implantation between first and second vertebrae, the implant comprising:

a first body member having a first end and a second end;

a second body member having a first end and a second end, the first end of the first body member positioned proximate the first end of the second body member in a collapsed position, the second body member including at least one ratchet thread tooth form formed thereon;

a drive ring rotatably attached to the first body member, the drive ring including an inner bore for receiving at least a portion of the second body member; and

a ratchet ring operatively associated with the drive ring, the ratchet ring including an inner bore having at least one corresponding ratchet thread tooth form formed thereon for engaging the ratchet thread tooth form of the second body member, wherein rotation of the drive ring causes rotation of the ratchet ring which in turn causes the second body member to axially move with respect to the first body member in a screw-type manner, the ratchet ring being radially flexible so that application of a predetermined force between the ratchet ring and the second body member causes the second body member to axially move relative to the first body member in a ratchet-type manner.

13. The implant of claim 12, wherein the second body member is slightly smaller than the first body member so that the second body member is at least partially received within the first body member.

14. The implant of claim 12, wherein the first body member is substantially cylindrical and includes an internal cavity, the second body member is a substantially cylindrical an includes an outer surface, the outer surface of the second body member including the ratchet thread tooth form for engaging the ratchet ring, the outer surface of the second body member is slidably receivable within the internal cavity of the first body member.

15. The implant of claim 12, wherein the drive ring includes a plurality of projections for mating with a circumferential groove formed on an outer surface of the first body member proximate the first end.

16. The implant of claim 12, wherein the ratchet ring includes at least one slot and a pair of ears positioned proximate the slot.

17. The implant of claim 12, wherein the first body member includes a first endplate for contacting the first vertebra and the second body member includes a second endplate for contacting the second vertebra, the first and second endplates are removeably coupled to the first and second body members, respectively.

18. A method of sizing an adjustable height intervertebral implant, including a first body member, a second body member and a collar operatively associated with the first body member, for implantation between first and second vertebrae, the method comprising:

a) applying at least a predetermined axial force to the first and second body members so that the second body member moves with respect to the first body member in an axial ratchet-type manner in order to approximate the space between the first and second vertebrae; and

b) rotating the collar with respect to the second body member so that the second body member axially moves with respect to the first body member.

19. The method of claim 18, further comprising:

c) implanting the intervertebral implant between the first and second vertebrae prior to steps (a) and (b).

20. The method of claim 18, further comprising:

c) applying a rotational force to a ring gear formed on the collar using a tool in step (b); and

d) inserting bone chips through a window and into a cavity formed in the implant to promote bone growth and fusion of the first and second vertebrae.