Method of making hydrogel implants

• US 7,682,540 B2
• Filed: 05/08/2008
• Issued: 03/23/2010
• Est. Priority Date: 02/06/2004
• Status: Active Grant

• Current Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Original Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Inventors: Kennedy, Stephen J., Boyan, Barbara D.
• Primary Examiner(s): Nguyen; Khanh
• Assistant Examiner(s): Gross; Carson
• Application Number:
  US12/117,667
• Publication Number:
  US 20080279943A1
• Time in Patent Office: 684 Days
• Field of Search: 264 131- 134, 264212-218, 264/299, 623 139- 14, 623 1611- 2363, 623 2371- 2376
• US Class Current: 264/212
• CPC Class Codes: A61L 27/16 obtained by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: A61L 27/52 Hydrogels or hydrocolloids
• CPC Class Codes: A61L 27/56 Porous materials, e.g. foams or sponges
• CPC Class Codes: A61P 19/00 Drugs for skeletal disorders
• CPC Class Codes: B33Y 80/00 Products made by additive manufacturing
• CPC Class Codes: C08L 29/04 Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids

Abstract

Implantable biomaterials, particularly hydrogel substrates with porous surfaces, and methods for enhancing the compatibility of biomaterials with living tissue, and for causing physical attachment between biomaterials and living tissues are provided. Also provided are implants suitable for load-bearing surfaces in hard tissue repair, replacement, or augmentation, and to methods of their use. One embodiment of the invention relates to an implantable spinal disc prosthesis.

Claims

1. A method of making a hydrogel having an outer surface and a plurality of first superficial pores and a plurality of second superficial pores along at least a portion of said outer surface, said method comprising:

providing a mold having an array of first projections and an array of second projections thereon for creating a plurality of first and second pores;

wherein said array of first projections is configured to form the plurality of first pores, each of said first pores being defined by a first cavity extending from the outer surface of the hydrogel to a bottom surface of said first cavity;

wherein said array of second projections extends from an end of at least one of the first projections, said second projections configured to form the plurality of second pores;

wherein each of said second pores is defined by a second cavity extending below the bottom surface of a first cavity;

casting a hydrogel in the mold;

allowing the hydrogel to form while in the mold; and

removing the hydrogel from the mold;

wherein said first cavities and said second cavities are only located on or near the outer surface of the hydrogel; and

wherein said hydrogel is adapted for long term or chronic implantation such that said hydrogel remains within a joint after implantation to augment cartilage and function as cartilage replacement.

2. The method of claim 1, wherein the providing a mold having first and second projections is accomplished at least partially with microelectromechanical systems (MEMS) technology or its equivalent.

3. The method of claim 1, wherein the hydrogel comprises polyvinyl alcohol.

4. The method of claim 3, wherein the content of said polyvinyl alcohol is at least 30% of the total hydrogel.

5. The method of claim 1, wherein both the first and the second cavities are arranged in a regular repeating fashion.

6. The method of claim 1, wherein the first cavities and the second cavities are within 1 millimeter of the outer surface of the hydrogel.

7. The method of claim 1, wherein the first cavities have an average cross-section of between 10 to 300 micrometers, and wherein the second cavities have an average cross-section of between 1 to 10 micrometers.

8. A method of making a substrate configured for use as a load bearing device within an anatomy, said method comprising:

providing a mold having a plurality of first and second projections thereon, said first and second projections corresponding to a plurality of first and second superficial cavities to be formed on or near an outer surface of the substrate;

wherein each of the first projections is configured to form a first cavity along the outer surface of the substrate;

wherein the plurality of second projections extend from at least one of the first projections of the mold, said second projections being configured to form a plurality of second cavities along a bottom surface of at least of the first cavities, each of said second cavities having a cross section that is smaller than a cross-section of the first cavities;

pouring a liquid solution of a hydrogel into the mold;

allowing the hydrogel to polymerize and crosslink while in the mold; and

removing the hydrogel from the mold;

wherein the second cavities are located within an area of the first cavities; and

wherein said substrate is configured for use as a cartilage replacement device.

9. The method of claim 8, wherein the providing a mold having projections is accomplished at least partially with microelectromechanical systems (MEMS) technology or its equivalent.

10. The method of claim 8, wherein the hydrogel comprises polyvinyl alcohol, and wherein the content of said polyvinyl alcohol is at least 30% of the total hydrogel.

11. The method of claim 8, wherein the first cavities and the second cavities are within 1 millimeter of the outer surface of the substrate.

12. The method of claim 8, wherein the first cavities have an average cross-section of between 10 to 300 micrometers, and wherein the second cavities have an average cross-section of between 1 to 10 micrometers.