Expandable spinal fusion device and methods of promoting spinal fusion

• US 7,018,415 B1
• Filed: 09/23/2002
• Issued: 03/28/2006
• Est. Priority Date: 09/23/2002
• Status: Active Grant

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: SDGI Holdings Incorporated (Medtronic Plc)
• Inventors: McKay, William F.
• Primary Examiner(s): REIP, DAVID OWEN
• Application Number:
  US10/252,299
• Time in Patent Office: 1,282 Days
• Field of Search: 623/17.11, 623/17.13, 623/17.12, 623/17.15, 623/17.16, 623/17.14
• US Class Current: 623/17.15
• CPC Class Codes: A61F 2/28 Bones joints A61F2/30
• CPC Class Codes: A61F 2/442 Intervertebral or spinal discs, e.g. resilient non-disc-shaped intervertebral inflatable pockets A61F2/441; non-disc-shaped intervertebral fusion implants A61F2/4455
• 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 2/446 having a circular or elliptical cross-section substantially parallel to the axis of the spine, e.g. cylinders or frustocones
• CPC Class Codes: A61F 2/447 substantially parallelepipedal, e.g. having a rectangular or trapezoidal cross-section
• CPC Class Codes: A61F 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2002/2817 Bone stimulation by chemical reactions or by osteogenic or biological products for enhancing ossification, e.g. by bone morphogenetic or morphogenic proteins [BMP] or by transforming growth factors [TGF]
• 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 2002/30069 elastomeric
• CPC Class Codes: A61F 2002/30092 using shape memory or superelastic materials, e.g. nitinol
• CPC Class Codes: A61F 2002/30113 circular
• CPC Class Codes: A61F 2002/30153 rectangular
• CPC Class Codes: A61F 2002/30225 Flat cylinders, i.e. discs
• CPC Class Codes: A61F 2002/30233 Stepped cylinders, i.e. having discrete diameter changes
• CPC Class Codes: A61F 2002/30265 Flat parallelepipeds
• CPC Class Codes: A61F 2002/30331 made by longitudinally pushing a protrusion into a complementarily-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2002/30364 Rotation about the common longitudinal axis
• CPC Class Codes: A61F 2002/30392 Rotation
• CPC Class Codes: A61F 2002/30393 with additional means for limiting said rotation
• CPC Class Codes: A61F 2002/30411 having two threaded end parts connected by a threaded central part with opposite threads at its opposite ends, i.e. for adjusting the distance between both end parts by rotating the central part
• CPC Class Codes: A61F 2002/30433 : using additional screws, bolts, dowels, rivets or washers e.g. connecting screws
• CPC Class Codes: A61F 2002/30451 : soldered or brazed or welded
• CPC Class Codes: A61F 2002/30462 : retained or tied with a rope, string, thread, wire or cable
• CPC Class Codes: A61F 2002/30476 : locked by an additional locking mechanism
• CPC Class Codes: A61F 2002/3052 : unrestrained in only one direction, e.g. moving unidirectionally
• CPC Class Codes: A61F 2002/30523 : by means of meshing gear teeth
• CPC Class Codes: A61F 2002/30525 : Worm gears
• CPC Class Codes: A61F 2002/3055 : for adjusting length
• CPC Class Codes: A61F 2002/30556 : for adjusting thickness
• CPC Class Codes: A61F 2002/30563 : having elastic means or damping means, different from springs, e.g. including an elastomeric core or shock absorbers
• CPC Class Codes: A61F 2002/30566 : Helical springs
• CPC Class Codes: A61F 2002/30571 : Leaf springs
• CPC Class Codes: A61F 2002/30579 : with mechanically expandable devices, e.g. fixation devices
• 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 2002/30772 : Apertures or holes, e.g. of circular cross section
• CPC Class Codes: A61F 2002/30841 : Sharp anchoring protrusions for impaction into the bone, e.g. sharp pins, spikes
• CPC Class Codes: A61F 2002/3085 : with a threaded, e.g. self-tapping, bone-engaging surface, e.g. external surface
• CPC Class Codes: A61F 2002/30975 : made of two halves
• CPC Class Codes: A61F 2210/0014 : using shape memory or superelastic materials, e.g. nitinol
• 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 2220/0041 : using additional screws, bolts, dowels or rivets, e.g. connecting screws
• CPC Class Codes: A61F 2220/0058 : soldered or brazed or welded
• CPC Class Codes: A61F 2220/0075 : sutured, ligatured or stitched, retained or tied with a rope, string, thread, wire or cable
• CPC Class Codes: A61F 2230/0006 : circular
• CPC Class Codes: A61F 2230/0019 : rectangular
• CPC Class Codes: A61F 2230/0069 : cylindrical
• CPC Class Codes: A61F 2230/0082 : parallelepipedal
• CPC Class Codes: A61F 2250/0009 : for adjusting thickness
• CPC Class Codes: A61F 2310/00293 : containing a phosphorus-containing compound, e.g. apatite

Abstract

An intervertebral disc space implant includes spaced-apart bone engagement portions that define an intermediate chamber that holds bone growth inducing material into contact with adjacent vertebral bodies. The implant is expandable to establish and maintain desired intervertebral spacing during fusion. The implant includes a first member and a second member arranged to move relative to each other by action of an expansion member, the first member being engageable with the vertebral body below the disc space.

Claims

1. A spinal implant positionable in an intervertebral disc space between adjacent vertebral bodies in a spine and comprising:

a first cam having a substantially planar face and an extension extending along an axis substantially perpendicular to said face;

a first member for contacting an endplate of one of the adjacent vertebral bodies, the first member having a first surface, at least a portion of the first surface being in physical contact with a portion of the first cam;

a second member for contacting an endplate of the other of the adjacent vertebral bodies, the second member having a second surface, at least a portion of the second surface being in physical contact with a portion of the first cam,

wherein the first cam is capable of causing one of the first member and the second member to move apart from the other of the first and second member without the first cam undergoing substantial translational displacement;

a second cam;

a third member for contacting the endplate of the one of the adjacent vertebral bodies, the third member having a third surface, at least a portion of the third surface being in physical contact with a portion of the second cam;

a fourth member for contacting the endplate of the other of the adjacent vertebral bodies, the fourth member having a fourth surface, at least a portion of the fourth surface being in physical contact with a portion of the second cam; and

an elongate member extending intermediate the first cam and the second cam, the elongate member having a first end region attached to one of the first cam and the second cam and a second end region attached to the other of the first cam and the second cam.

2. A spinal implant positionable in an intervertebral disc space between adjacent vertebral bodies in a spine and comprising:

a first cam;

a first member for contacting an endplate of one of the adjacent vertebral bodies, the first member having a first surface, at least a portion of the first surface being in physical contact with a portion of the first cam;

a second member of contacting an endplate of the other of the adjacent vertebral bodies, the second member having a second surface, at least a portion of the second surface being in physical contact with a portion of the first cam; and

wherein the first cam is capable of causing one of the first member and the second member to move apart from the other of the first and second member without the first cam undergoing substantial translational displacement; and

a second cam;

a third member for contacting the endplate of the one of the adjacent vertebral bodies, the third member having a third surface, at least a portion of the third surface being in physical contact with a portion of the second cam;

a fourth member for contacting the endplate of the other of the adjacent vertebral bodies, the fourth member having a fourth surface, at least a portion of the fourth surface being in physical contact with a portion of the second cam;

an elongate member extending intermediate the first cam and the second cam, the elongate member having a first end region attached to one of the first cam and the second cam and a second end region attached to the other of the first cam and the second cam; and

;

wherein the first member and the second member are spaced apart from the third member and the fourth member thereby defining walls for an intermediate chamber between and communicable with the endplates of both of the adjacent vertebral bodies.

3. The implant of claim 2 further comprising an osteogenic fusion promoting material disposed between said walls for engagement with the endplates of the adjacent vertebral bodies.

4. The implant of claim 3 wherein the osteogenic fusion promoting material is selected from the group consisting of BMP, LMP, and DBM.

5. A spinal implant for insertion within the disc space between adjacent vertebral bodies and comprising:

a first end member having a first portion for engaging an endplate of one of said adjacent vertebral bodies and having a second portion for engaging an endplate of the other of said adjacent vertebral bodies, the first portion and second portion being spaced apart;

a second end member having a third portion for engaging the endplate of one of said adjacent vertebral bodies and having a fourth portion for engaging the endplate of the other of said adjacent vertebral bodies, the third portion being spaced apart from the fourth portion; and

means engaging said first and second end members for changing spacing between said first and second portions and for changing the spacing between said third and fourth portions, said means including a first piece engaging said first and second portions, a second piece engaging said third and fourth portions, and a third piece linking said first and second pieces.

6. The spinal implant of claim 5 and wherein the means for changing the spacing is selected from the group consisting of a cam mechanism, a screw mechanism, a rack and pinion mechanism, and a biasing mechanism.

7. The spinal implant of claim 5 and further comprising:

an elongate member intermediate said first end member and said second end member for cooperating with faces of said first and second end members to define a chamber between the endplate of said one vertebral body and the endplate of said other vertebral body for receiving bone growth inducing material within said chamber.

8. The combination of claim 7 and further comprising:

bone growth material received between said end members and around said elongate member to fill said chamber.

9. The combination of claim 8 and wherein the bone growth inducing material is selected from a group consisting of bone, BMP, LMP, and DBM.

10. The spinal implant of claim 5 and wherein:

said first and second end members have a rectangular shape.

11. The spinal implant of claim 5 and wherein:

the first and second end members have short parallelepiped shapes.

12. The spinal implant of claim 5 and further comprising:

an elongate member connected to said end members and having a longitudinal axis; and

said end members are polygonal in spaced planes perpendicular to said longitudinal axis.

13. The spinal implant of claim 12 and wherein:

said portions for engaging said vertebral bodies have surface projections for anchoring in said vertebral bodies.

14. The spinal implant of claim 13 and wherein:

said surface projections are barbs.

15. A spinal implant positionable in an intervertebral disc space between adjacent vertebral bodies in a spine and comprising:

a first cam;

a first member for contacting an endplate of one of the adjacent vertebral bodies, the first member having a first surface, at least a portion of the first surface being in physical contact with a portion of the first cam;

a second member of contacting an endplate of the other of the adjacent vertebral bodies, the second member having a second surface, at least a portion of the second surface being in physical contact with a portion of the first cam; and

wherein the first cam is capable of causing one of the first member and the second member to move apart from the other of the first and second member without the first cam undergoing substantial translational displacement; and

an assembly connecting mechanism including a first object protruding from the first cam; and

a slot in the first member shaped to receive the first object, and

a second cam;

a third member for contacting the endplate of the one of the adjacent vertebral bodies, the third member having a third surface, at least a portion of the third surface being in physical contact with a portion of the second cam;

a fourth member for contacting the endplate of the other of the adjacent vertebral bodies, the fourth member having a fourth surface, at least a portion of the fourth surface being in physical contact with a portion of the second cam;

an elongate member extending intermediate the first cam and the second cam, the elongate member having a first end region attached to one of the first cam and the second cam and a second end region attached to the other of the first cam and the second cam.

16. The apparatus of claim 15, wherein the first member and the second member are spaced apart from the third member and the fourth member thereby defining walls for an intermediate chamber between and communicable with the endplates of both of the adjacent vertebral bodies.

17. A spinal implant positionable in an intervertebral disc space between adjacent vertebral bodies in a spine and comprising:

a first cam;

a first member for contacting an endplate of one of the adjacent vertebral bodies, the first member having a first surface, at least a portion of the first surface being in physical contact with a portion of the first cam;

a second member for contacting an endplate of the other of the adjacent vertebral bodies, the second member having a second surface, at least a portion of the second surface being in physical contact with a portion of the first cam;

a second cam;

a third member for contacting the endplate of the one of the adjacent vertebral bodies, the third member having a third surface, at least a portion of the third surface being in physical contact with a portion of the second cam;

a fourth member for contacting the endplate of the other of the adjacent vertebral bodies, the fourth member having a fourth surface, at least a portion of the fourth surface being in physical contact with a portion of the second cam;

an elongate member extending intermediate the first cam and the second cam, the elongate member having a first end region attached to one of the first cam and the second cam and a second end region attached to the other of the first cam and the second cam;

wherein at least one of said cams is capable of causing at least one of said members it contacts to move apart from the other without said cams undergoing substantial translational displacement.