Intervertebral disc prosthesis with liquid chamber

• US 6,395,032 B1
• Filed: 06/07/2001
• Issued: 05/28/2002
• Est. Priority Date: 12/11/1998
• Status: Expired due to Term

• Current Assignee: Stryker European Operations Holdings, LLC (Stryker Corporation)
• Original Assignee: Dimso
• Inventors: Gauchet, Fabien
• Primary Examiner(s): Smith, Jeffrey A.
• Assistant Examiner(s): Priddy, Michael B
• Application Number:
  US09/857,657
• Time in Patent Office: 355 Days
• Field of Search: 623/17.11-17.16
• US Class Current: 623/17.12
• CPC Class Codes: A61B 17/7059 Cortical plates A61B17/7007, A61B17/7058 take precedence
• CPC Class Codes: A61B 17/86 Pins or screws or threaded wires; nuts therefor A61B17/72 take precedence
• CPC Class Codes: A61F 2/30742 Bellows or hose-like seals; Sealing membranes A61B17/8808 takes precedence; sealing membranes for retaining bone substitute A61F2/2846
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/441 made of inflatable pockets or chambers filled with fluid, e.g. with hydrogel
• 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 2002/30133 kidney-shaped or bean-shaped
• CPC Class Codes: A61F 2002/30224 cylindrical
• CPC Class Codes: A61F 2002/30329 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2002/30448 using adhesives
• 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 2002/30565 having spring elements
• CPC Class Codes: A61F 2002/30578 having apertures, e.g. for receiving fixation screws
• CPC Class Codes: A61F 2002/30581 having a pocket filled with fluid, e.g. liquid
• CPC Class Codes: A61F 2220/0025 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/005 using adhesives
• CPC Class Codes: A61F 2230/0015 Kidney-shaped, e.g. bean-shaped
• 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 2310/00796 Coating or prosthesis-covering structure made of a phosphorus-containing compound, e.g. hydroxy(l)apatite

Abstract

An intervertebral disc prosthesis includes two opposing plates and a flexible seal extending between the two plates for forming a closed chamber therebetween. The disc prosthesis also includes a liquid provided in the chamber and a body disposed in the liquid and the chamber, the body having a plurality of pores at an outer surface thereof and cavities extending from the pores into the body. The liquid and the body are selected from materials so that said liquid does not normally wet to said cavities and compressive energy must be applied to the liquid for forcing the liquid into the cavities.

Claims

1. An intervertebral disc prosthesis comprising:

two opposing plates;

a flexible seal extending between said two plates for

forming a closed chamber between said two plates;

a liquid provided in said chamber; and

a body disposed in said chamber and in said liquid, said body having a plurality of pores at an outer surface thereof and cavities extending from said pores into said body, wherein said liquid and said body are selected from materials so that said liquid does not normally wet to said cavities and compressive energy must be applied to said liquid for forcing said liquid into said cavities.

2. The prosthesis as claimed in claim 1, wherein said cavities are in communication with one another within said body.

3. The prosthesis as claimed in claim 2, wherein said cavities are microscopic.

5. The prosthesis as claimed in claim 2, wherein said two opposing plates are movable relative to one another.

9. The prosthesis as claimed in claim 1, wherein at least one of said plates is securable to bone.

10. The prosthesis as claimed in claim 9, wherein the at least one of said plates securable to bone has at least one lug projecting from a face thereof, said lug having an orifice adapted to receive a screw insertible into the bone.

11. The prosthesis as claimed in claim 1, wherein said body is fixed to one of said plates and movable relative to the other of said plates.

12. The prosthesis as claimed in claim 1, wherein said flexible seal includes a bellows having an upper edge secured to one of said plates and a lower edge secured to the other of said plates.

13. The prosthesis as claimed in claim 1, wherein said flexible seal is made of a material selected from the group consisting of titanium and titanium alloys.

14. The prosthesis as claimed in claim 1, wherein said body is made of a material selected from the group consisting of titanium and titanium alloys.

15. The prosthesis as claimed in claim 1, wherein said liquid comprises water.

16. The prosthesis as claimed in claim 1, further comprising a pocket of gas provided inside said chamber and in said liquid.

17. The prosthesis as claimed in claim 1, wherein said body is movable freely within said chamber and relative to said opposing plates.

18. The prosthesis as claimed in claim 1, wherein movement of said opposing plates relative to one another is dampened by circulation of said liquid through said cavities of said body.

19. The prosthesis as claimed in claim 1, wherein said opposing plates are compressible toward one another along a main axis of compression.

20. The prosthesis as claimed in claim 19, wherein said flexible seal normally maintains said opposing plates at a first spaced distance relative to one another when no compression forces are applied to said plates.

21. The prosthesis as claimed in claim 20, wherein said opposing plates are compressible to a second spaced distance that is less than said first spaced distance when compression forces are applied to said opposing plates.

22. The prosthesis as claimed in claim 21, wherein the spaced distance of said plates relative to one another as a function of the compression forces applied to said plates follows a graph curve having a hysteresis form.

4. The prosthesis as claimed 1, wherein the energy applied to said liquid is dissipated as said liquid circulates through said cavities of said body.

6. The prosthesis as claimed in claim 4, wherein said cavities are adapted to store the energy applied to said liquid when said liquid is forced into said cavities.

7. The prosthesis as claimed in claim 6, wherein said cavities are adapted to release the energy applied to said liquid as said liquid recedes from said cavity.

8. The prosthesis as claimed in claim 7, wherein said body is adapted to store at least some of the energy applied to said liquid therein when said opposing plates move toward one another, and release the at least some of the energy stored therein when said opposing plates move away from one another.

23. An intervertebral disc prosthesis comprising:

two opposing plates movable relative to one another, at least one of said plates including a securing element for securing said prosthesis to bone;

a flexible seal extending between said two opposing plates for forming a fluid-tight chamber between said two opposing plates;

a liquid provided in said fluid-tight chamber and between said opposing plates, wherein said plates are adapted to transfer compressive energy to said liquid when said plates move toward one another;

a porous body disposed in said fluid-tight chamber, said porous body having a plurality of pores at an outer surface thereof and cavities extending from said pores into said body, wherein the compressive energy transferred to said liquid when said plates move toward one another forces at least some of the liquid into the cavities of said body.

24. The prosthesis as claimed in claim 23, wherein the energy in said liquid is transferred to said body as the liquid is forced into said cavities.

25. A method of damping movement of opposing plates of an intervertebral disc prosthesis comprising:

providing the intervertebral disc prosthesis including two opposing plates, a flexible seal extending between said two plates for forming a closed chamber between said two plates, a liquid in said closed chamber, a porous body having internal cavities disposed in said chamber and said liquid, wherein said body and said liquid are selected so that said liquid does not normally wet to the cavities of said body;

applying compressive forces on said plates for moving said plates toward one another, transferring the compressive forces to said liquid for forcing said liquid into the cavities of said body, wherein said liquid stores at least some of the compressive force applied to said liquid through compression of said plates.

26. The method as claimed in claim 25, further comprising:

removing the compressive forces on said plates, whereupon the liquid in said cavities recedes from said cavities and returns to said chamber.