Prosthetic disc containing therapeutic material

• US 4,904,260 A
• Filed: 07/25/1988
• Issued: 02/27/1990
• Est. Priority Date: 08/20/1987
• Status: Expired due to Term

• Current Assignee: Raymedica, Inc.
• Original Assignee: Cedar Surgical Incorporated
• Inventors: Corbin, Terry P., Ray, Charles D.
• Primary Examiner(s): Apley, Richard J.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US07/223,400
• Time in Patent Office: 582 Days
• Field of Search: 604/93, 604/131, 604/175, 604/891.1, 604/892.1, 623/7, 623/8, 623/16, 623/17, 623/66, 623/11, 623/12, 128/69, 128/92 YM, 424/422-426, 424/DIG. 7, 530/353-365
• US Class Current: 623/17.12
• CPC Class Codes: A61F 2/30965 Reinforcing the prosthesis by embedding particles or fibres during moulding or dipping
• CPC Class Codes: A61F 2/44 for the spine, e.g. vertebrae, spinal discs
• 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 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2002/30062 (bio)absorbable, biodegradable, bioerodable, (bio)resorbable, resorptive
• CPC Class Codes: A61F 2002/30235 tubular, e.g. sleeves
• CPC Class Codes: A61F 2002/30677 Means for introducing or releasing pharmaceutical products, e.g. antibiotics, into the body
• 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 2002/4627 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 2210/0004 bioabsorbable
• CPC Class Codes: A61F 2230/0069 cylindrical
• CPC Class Codes: A61L 2430/38 for reconstruction of the spine, vertebrae or intervertebral discs
• CPC Class Codes: A61L 27/04 Metals or alloys
• CPC Class Codes: A61L 27/44 having a macromolecular matrix
• CPC Class Codes: C08L 67/04 Polyesters derived from hydroxycarboxylic acids, e.g. lactones C08L67/06 takes precedence
• CPC Class Codes: C08L 89/06 derived from leather or skin , e.g. gelatin
• CPC Class Codes: Y10S 128/20 Inflatable splint
• CPC Class Codes: Y10S 424/07 Microporous membranes

Abstract

By implanting two prosthetic disc capsules side-by-side into a damaged disc of a human spine, both height and motion, including front-to-back bending, can be maintained. Each prosthetic disc capsule has a bladder enclosing a fluid containing a therapeutic material that is slowly diffusible through a semi-permeable membrane of the bladder. The fluid filling the semi-permeable membrane preferably is an aqueous solution that has gel-like properties that afford a viscosity and velocity-shear behavior imitating the natural rheology of intradiscal nuclear tissue. Those properties are obtained when the aqueous solution is of a mucopolysaccharide such as hyaluronic acid or soldium hyaluronate.

Claims

1. An elongated cylindrical prosthetic intervertebral disc capsule having a diameter approximating the height of a human disc space and a length approaching the sagittal diameter of the vertebral body, said capsule comprising:

a flexible bladder which is chemically and biologically inert and comprises a semi-permeable membrane enclosing a fluid containing a therapeutic material that is slowly diffusible through the semi-permeable membrane, and

a layer of strong fibers encompassing the fluid-filled membrane.

2. A prosthetic disc capsule as defined in claim 1 wherein the semi-permeable membrane is a microporous organic film.

3. A prosthetic disc capsule as defined in claim 2 wherein the microporous organic film is microporous polytetrafluoroethylene.

4. A prosthetic disc capsule as defined in claim 1 wherein the semi-permeable membrane is a tightly woven fabric of oriented poly(ethylene terephthalate) fibers that has been plasma-deposited with polytetrafluoroethylene.

5. A prosthetic disc capsule as defined in claim 1 wherein the pore size of the semi-permeable membrane is sufficiently small to block the passage of human cells.

6. A prosthetic disc capsule as defined in claim 5 wherein the pore size of the semi-permeable membrane is on the order of 1-7 micrometers.

7. A prosthetic disc capsule as defined in claim 1 wherein the bladder also comprises flexible impermeable organic film.

8. A prosthetic disc capsule as defined in claim 7 wherein the semi-permeable membranee is a tube, the diameter of which approximates the thickness of a human disc, and the length of which approximates the sagittal diameter of the vertebral body, and he ends of the tube are sealed to circles of an impermeable organic film.

9. A prosthetic disc capsule as defined in claim 1 wherein the fluid filling the bladder is a gel having a viscosity and velocity-shear behavior imitating the natural rheology of intradiscal nuclear tissue.

10. A prosthetic disc capsule as defined in claim 9 wherein the fluid filling the bladder is an aqueous solution of a mucopolysaccharide.

11. A prosthetic disc capsule as defined in claim 10 wherein the mucopolysaccharide is selected from hyaluronic acid and sodium hyaluronate.

12. A prosthetic disc capsule as defined in claim 1 having strong, inert fibers woven into the outer layer and extending transversely through the semi-permeable membrane to limit lateral bulging.

13. A prosthetic disc capsule as defined in claim 12 wherein a bioresorbable material is intermingled with the inert fibers.

14. A prosthetic disc capsule as defined in claim 13 wherein said bioresorbable material comprises fibers which are interwoven with said inert fibers.

15. A prosthetic disc capsule as defined in claim 13 wherein said bioresorbable material is coated on the inert fibers.

16. A prosthetic disc capsule as defined in claim 1 and including a hollow tubing communicating with the interior of said membrane and an external chamber, and means for injecting or withdrawing fluid into or from the chamber.

17. An elongated cylindrical prosthetic intervertebral disc capsule having a diameter approximating the height of a human disc space and a length approaching the sagittal diameter of the vertebral body, said capsule comprising:

a flexible bladder which

is chemically and biologically inert, and which comprises a semi-permeable membrane,

enclosing a fluid containing a therapeutic material that is slowly diffusible thrugh the semi-permeable membrane, and

through which the therapeutic material is slowly diffusible but through which cells will not pass, and said capsule further comprising

a layer of strong fibers encompassing the fluid-filled membrane.