Intervertebral stabilizer

• US 20060200242A1
• Filed: 07/07/2005
• Published: 09/07/2006
• Est. Priority Date: 03/03/2005
• Status: Active Grant

• Current Assignee: Cardo Medical LLC (BioCardia, Inc)
• Original Assignee: Accin Corp.
• Inventors: Zubok, Rafail, Rothman, Richard H., Kvitnitsky, Mikhail
• Granted Patent: US 7,578,848 B2
• Time in Patent Office: Days
• US Class Current: 623/17.130
• CPC Class Codes: A61B 2017/0256 for the spine
• CPC Class Codes: A61F 2/44 for the spine, e.g. vertebrae, spinal discs
• 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 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2/4684 Trial or dummy prostheses
• CPC Class Codes: A61F 2002/30014 differing in elasticity, stiffness or compressibility
• CPC Class Codes: A61F 2002/3013 figure-"8"- or hourglass-shaped
• CPC Class Codes: A61F 2002/30133 kidney-shaped or bean-shaped
• CPC Class Codes: A61F 2002/30235 tubular, e.g. sleeves
• CPC Class Codes: A61F 2002/30327 differing in diameter
• 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 2002/30429 made by inserting a hook into a cooperating slot
• CPC Class Codes: A61F 2002/30566 Helical springs
• CPC Class Codes: A61F 2002/30578 having apertures, e.g. for receiving fixation screws
• CPC Class Codes: A61F 2002/30594 slotted, e.g. radial or meridian slot ending in a polar aperture, non-polar slots, horizontal or arcuate slots
• 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 2002/30795 Blind bores, 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 2002/30878 with non-sharp protrusions, for instance contacting the bone for anchoring, e.g. keels, pegs, pins, posts, shanks, stems, struts
• CPC Class Codes: A61F 2002/448 : comprising multiple adjacent spinal implants within the same intervertebral space or within the same vertebra, e.g. comprising two adjacent spinal implants
• CPC Class Codes: A61F 2002/4619 : for extraction
• 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 2002/4628 : with linear motion along or rotating motion about an axis transverse to the instrument axis or to the implantation direction, e.g. clamping
• CPC Class Codes: A61F 2002/4629 : connected to the endoprosthesis or implant via a threaded connection
• 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 2230/001 : Figure-8-shaped, e.g. hourglass-shaped
• CPC Class Codes: A61F 2230/0015 : Kidney-shaped, e.g. bean-shaped
• CPC Class Codes: A61F 2230/0069 : cylindrical
• CPC Class Codes: A61F 2250/0018 : differing in elasticity, stiffness or compressibility
• CPC Class Codes: A61F 2250/0039 : differing in diameter

Abstract

An intervertebral stabilizer includes: a first surface operable to engage an endplate of a first vertebral bone of a spine; a second surface spaced apart from the first surface and operable to engage an endplate of an adjacent second vertebral bone of the spine; a spring element between the first and second surfaces and operable to provide reactive force in response to compression loads from the first and second vertebral bones, wherein a cross-sectional profile taken through the surfaces is hourglass shaped.

Claims

1. An intervertebral stabilizer, comprising:

a first surface operable to engage an endplate of a first vertebral bone of a spine;

a second surface spaced apart from the first surface and operable to engage an endplate of an adjacent second vertebral bone of the spine;

a spring element including helical coils disposed between the first and second surfaces and operable to provide reactive force in response to compression loads from the first and second vertebral bones,

wherein at least some diameters of respective turns of the helical coils differ.

2. The intervertebral stabilizer of claim 1, wherein those of the turns having larger diameters are disposed towards the first and second surfaces and those of the turns having smaller diameters are centrally located between the turns having larger diameters.

3. The intervertebral stabilizer of claim 1, wherein a cross-sectional profile taken through the spring element is at least partially hourglass shaped.

4. The intervertebral stabilizer of claim 3, wherein the cross-sectional profile taken through the spring element has a multiple hourglass shape.

5. The intervertebral stabilizer of claim 1, wherein at least one of:

the first surface includes a peripheral edge that overhangs at least one coil of the spring element; and

the second surface includes a peripheral edge that overhangs at least one coil of the spring element.

6. The intervertebral stabilizer of claim 5, wherein at least one of:

a first moment arm is defined by a lateral distance between an outer surface of the at least one coil of the spring element and the peripheral edge of the first surface; and

a second moment arm is defined by a lateral distance between the outer surface of the at least one coil of the spring element and the peripheral edge of the second surface.

7. The intervertebral stabilizer of claim 6, wherein at least one of the moment arms defined by the hourglass shape operates such that:

a compressive force acting on one of the peripheral edges and the other of the first and second surfaces tends to collapse the spring element and full compression of the spring element in response to the compressive force results in adjacent coils engaging one another; and

further compressive force acting on only a portion of the peripheral edge tends to cause the adjacent coils to engage one another and to expand portions of coils on an opposite side of the spring element from the engaged coils.

8. The intervertebral stabilizer of claim 1, wherein the spring element is formed from at least one of:

a helical wound spring; and

a hollow body having at least one slit forming a plurality of annular circumferential helical coils.

9. The intervertebral stabilizer of claim 1, further comprising one or more bone adhesion facilitating elements operable to promote bone adhesion to at least one of the first and second surfaces.

10. The intervertebral stabilizer of claim 9, wherein the one or more bone adhesion facilitating elements includes at least one of:

one or more spikes extending from at least one of the first and second surfaces for promoting engagement thereof with the associated vertebral bones;

one or more keels extending from at least one of the first and second surfaces for promoting engagement thereof with the associated vertebral bones; and

one or more roughening elements one at least one of the first and second surfaces for promoting engagement thereof with the associated vertebral bones.

11. The intervertebral stabilizer of claim 1, further comprising a hollow body forming a passage between the first and second surfaces and having at least one slit forming a plurality of annular circumferential helical coils forming the spring element.

12. The intervertebral stabilizer of claim 11, wherein:

the first surface includes a peripheral edge that overhangs at least one coil of the spring element;

a moment arm is defined by a lateral distance between an outer surface of the at least one coil of the spring element and the peripheral edge of the first surface; and

the passage is sized and shaped to maximize a length the moment arm.

13. The intervertebral stabilizer of claim 11, further comprising a membrane disposed in the passage and substantially closing off the passage to inhibit bone growth therethrough.

14. The intervertebral stabilizer of claim 13, wherein the membrane is formed as an integral element of the hollow body.

15. The intervertebral stabilizer of claim 1, further comprising a hollow body between the first and second surfaces and having at least one slit forming a plurality of annular circumferential helical coils forming the spring element, wherein the surfaces and the spring element are formed as an integral element from the hollow body.

16. An intervertebral stabilizer, comprising:

a first surface operable to engage an endplate of a first vertebral bone of a spine;

a second surface spaced apart from the first surface and operable to engage an endplate of a second vertebral bone of the spine;

a first rigid element; and

first and second spring elements, each including helical coils, the first spring element being disposed between the first rigid element and the first surface, the second spring element being disposed between the first rigid element and the second surface, and each spring element being operable to provide reactive force in response to compression loads from the first and second vertebral bones.

17. The intervertebral stabilizer of claim 16, further comprising:

a second rigid element; and

a third spring element,

wherein the first spring element is disposed between the first rigid element and the first surface, the second spring element is disposed between the first rigid element and the second rigid element, and the third spring element is disposed between the second rigid element and the second surface.

18. The intervertebral stabilizer of claim 16, wherein at least some diameters of respective turns of the helical coils differ.

19. The intervertebral stabilizer of claim 18, wherein those of the turns having larger diameters are disposed towards the first and second surfaces and those of the turns having smaller diameters are centrally located between the turns having larger diameters.

20. The intervertebral stabilizer of claim 16, wherein a cross-sectional profile taken through at least one of the spring elements is at least partially hourglass shaped.