Artificial intervertebral disc

• US 6,645,248 B2
• Filed: 08/23/2002
• Issued: 11/11/2003
• Est. Priority Date: 08/24/2001
• Status: Expired due to Fees

• Current Assignee: Zimmer GmbH (Zimmer Biomet Holdings, Inc.)
• Original Assignee: Sulzer Orthopedics Inc. (Centerpulse Orthopedics Incorporated)
• Inventors: Casutt, Simon
• Primary Examiner(s): SNOW, BRUCE EDWARD
• Application Number:
  US10/226,524
• Publication Number:
  US 20030045939A1
• Time in Patent Office: 445 Days
• Field of Search: 623/17.11, 623/17.12, 623/17.13, 623/17.14, 623/17.15, 606/61
• US Class Current: 623/17.12
• 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 2/30744 End caps, e.g. for closing an endoprosthetic cavity
• 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 2002/30014 differing in elasticity, stiffness or compressibility
• CPC Class Codes: A61F 2002/30235 tubular, e.g. sleeves
• CPC Class Codes: A61F 2002/30383 made by laterally inserting a protrusion, e.g. a rib into a complementarily-shaped groove
• CPC Class Codes: A61F 2002/30433 using additional screws, bolts, dowels, rivets or washers e.g. connecting screws
• CPC Class Codes: A61F 2002/30448 using adhesives
• CPC Class Codes: A61F 2002/30451 soldered or brazed or welded
• CPC Class Codes: A61F 2002/30495 using a locking ring
• CPC Class Codes: A61F 2002/30517 using a locking plate
• 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 2002/30588 filled with solid particles
• CPC Class Codes: A61F 2002/30879 Ribs
• CPC Class Codes: A61F 2002/30884 Fins or wings, e.g. longitudinal wings for preventing rotation within the bone cavity
• CPC Class Codes: A61F 2002/30909 Nets
• CPC Class Codes: A61F 2002/443 having two transversal endplates and at least one intermediate component
• CPC Class Codes: A61F 2002/4495 having a fabric structure, e.g. made from wires or fibres
• CPC Class Codes: A61F 2220/0025 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0041 : using additional screws, bolts, dowels or rivets, e.g. connecting screws
• CPC Class Codes: A61F 2220/005 : using adhesives
• CPC Class Codes: A61F 2220/0058 : soldered or brazed or welded
• CPC Class Codes: A61F 2230/0069 : cylindrical
• CPC Class Codes: A61F 2250/0018 : differing in elasticity, stiffness or compressibility
• CPC Class Codes: A61F 2310/00023 : Titanium or titanium-based alloys, e.g. Ti-Ni alloys

Abstract

The invention relates to an artificial intervertebral disc for implanting between two vertebral bodies (W) comprising two end plates (1, 2) which bound a hollow space (4), which is filled with an elastically and/or plastically deformable nucleus (3), at two opposite sides, with the hollow space (4) being enclosed by a tubular fiber ring (5) such that the end plates (1, 2), together with the fiber ring (5), bound the hollow space (4) and the end plates (1, 2) are in tensile connection with the fiber ring (5). The fiber ring (5) is designed as elastically extensible in the radial and axial directions, with the fiber ring (5) having a larger modulus of elasticity than the nucleus (3) and the nucleus (3) and the fiber ring (5) interacting such that the elastic properties of the artificial intervertebral disc show a non-linear behavior with increasing deformation at least with respect to a compression force (F).

Claims

1. An artificial intervertebral disc for implanting between two vertebral bodies (W) comprising two end plates (1, 2) which bound a hollow space (4), which is filled with an elastically and/or plastically deformable nucleus (3), at two opposite sides, the hollow space (4) comprising an inner region and an outer region surrounding the inner region, the outer region being bounded by opposing faces of the end plates, and the inner region being bounded by a concave bearing face of the one end plate and an opposing convex counterface of the other end plate, the distance between the concave bearing face of the one end plate and the opposing convex counterface of the other end plate in the inner region being smaller than the distance between the opposing faces of the end plates in the outer region, with the hollow space (4) being enclosed by a tubular fibre ring (5) such that the end plates (1, 2), together with the fibre ring (5), bound the hollow space (4) and the end plates (1, 2) are in tensile connection with the fibre ring (5), wherein the fibre ring (5) is designed as elastically extensible in the radial and axial directions, with the fibre ring (5) having a larger modulus of elasticity than the nucleus (3) and the nucleus (3) and the fibre ring (5) interacting such that the elastic properties of the artificial intervertebral disc show a non-linear behaviour with increasing deformation at least with respect to a compression force (F).

2. An artificial intervertebral disc in accordance with claim 1, in which the nucleus (3) is made up of a material whose modulus of elasticity has a value lower than 100 MPa.

3. An artificial intervertebral disc in accordance with claim 1, in which the value for the stiffness of the artificial intervertebral disc lies in a range between 2000 N/mm and 20,000 N/mm when the intervertebral disc is subject to a compression force (F) below 3000 N.

4. An artificial intervertebral disc in accordance with claim 1, in which the fibre ring (5) consists of a fabric, knitted fabric or braided fabric and comprises one or more layers.

5. An artificial intervertebral disc in accordance with claim 1, in which the materials making up the fibre ring (5) comprise one or more plastics such as polyamide, polyimide, carbon fibres, polyether etherketone (PEEK), or polyethylene terephthalate (PET).

6. An artificial intervertebral disc in accordance with claim 1, in which the nucleus (3) is selected from the group consisting of a hydrogel;

an elastic plastic based on silicone;

another elastic plastic;

a hydrogel and an elastic plastic based on silicone;

a hydrogel and another elastic plastic;

an elastic plastic based on silicone and another elastic plastic; and

a hydrogel, an elastic plastic based on silicone, and another elastic plastic.

7. An artificial intervertebral disc in accordance with claim 1, in which the hollow space (6) is accessible by a closable opening (6) in an end plate (1, 2).

8. An artificial intervertebral disc in accordance with claim 1, in which a build height (H) is either constant or reduces from anterior (A) to posterior (P).

9. An artificial intervertebral disc in accordance with claim 1, in which the end plates (1, 2) consist of a metal, of titanium, of a titanium alloy or of plastic.

10. An artificial intervertebral disc in accordance with claim 1, in which the end plates (1, 2) are made as anchoring platforms in order to achieve an intergrowth of the adjoining vertebral bodies (W) with the outwardly directed surfaces (7, 8) of the end plates (1, 2).

11. An artificial intervertebral disc in accordance with claim 10, at which the fibre ring (5) is adhesively bonded or welded at one of the grooves (9, 10) for connection to one of the end plates (1, 2).

12. An artificial intervertebral disc in accordance with claim 1, in which one of the end plates (1, 2) has a groove (9, 10) extending in the peripheral direction in order to accept the fibre ring (5).

13. An artificial intervertebral disc in accordance with claim 12, at which the fibre ring (5) is pressed in one of the grooves (9, 10) by cold shaping for connection to one of the end plates (1, 2).

14. An artificial intervertebral disc in accordance with claim 12, at which the fibre ring (5) is fixed in one of the grooves (9, 10) by an annular clamping element (11) for connection to one of the end plates (1, 2).

15. An artificial intervertebral disc in accordance with claim 12, at which the fibre ring (5) is injection moulded with plastic in an annular manner in one of the grooves (9, 10) of the end plates (1, 2) for connection to one of the end plates (1, 2).

16. An artificial intervertebral disc in accordance with claim 1, at which the fibre ring (5) is fixed by a holding element (12) for connection to one of the end plates (1, 2).

17. An artificial intervertebral disc in accordance with claim 16, in which the holding element is a screw connection (13).

18. An artificial intervertebral disc in accordance with claim 1, at which the fibre ring (5) is injection moulded with plastic at one of the surfaces (7, 8) for connection to one of the end plates (1, 2).

19. An artificial intervertebral disc in accordance with claim 1, in which the end plates (1, 2) have a projecting central rib (14), which extends along the end plates (1, 2).

20. An artificial intervertebral disc in accordance with claim 1, in which the end plates (1, 2) have a toothed arrangement (15) directed towards an outer edge of a vertebral body (W) so that an intergrowth of bone material between the toothed arrangement (15) and the vertebral body (W) allows for the transfer of torsion and flexion forces.