Moldable, hand-shapable biodegradable implant material

• US 5,716,413 A
• Filed: 10/11/1995
• Issued: 02/10/1998
• Est. Priority Date: 10/11/1995
• Status: Expired due to Term

• Current Assignee: OsteoBiologics Inc. (Smith & Nephew PLC)
• Original Assignee: OsteoBiologics Inc. (Smith & Nephew PLC)
• Inventors: Walter, Mary Ann, Leatherbury, Neil C., Niederauer, Mark Q.
• Primary Examiner(s): Weiss, John G.
• Assistant Examiner(s): CUDDIHY, FRANCIS KEVIN
• Application Number:
  US08/540,788
• Time in Patent Office: 853 Days
• Field of Search: 264/219, 264/232, 264/349, 264/41, 623/1, 623/11, 623/12, 623/16, 623/66, 623/901
• US Class Current: 424/423
• CPC Class Codes: A61F 2/28 Bones joints A61F2/30
• CPC Class Codes: A61F 2/30756 Cartilage endoprostheses A61F2/3603 takes precedence
• CPC Class Codes: A61F 2/3859 Femoral components
• CPC Class Codes: A61F 2/4455 for the fusion of spinal bodies, e.g. intervertebral fusion of adjacent spinal bodies, e.g. fusion cages intervertebral discs A61F2/442
• CPC Class Codes: A61F 2002/2807 Chin implants
• CPC Class Codes: A61F 2002/2835 Bone graft implants for filling a bony defect or an endoprosthesis cavity, e.g. by synthetic material or biological material
• CPC Class Codes: A61F 2002/2878 for orbital repair
• CPC Class Codes: A61F 2002/30062 (bio)absorbable, biodegradable, bioerodable, (bio)resorbable, resorptive
• CPC Class Codes: A61F 2002/30677 Means for introducing or releasing pharmaceutical products, e.g. antibiotics, into the body
• CPC Class Codes: A61F 2002/30766 Scaffolds for cartilage ingrowth and regeneration
• CPC Class Codes: A61F 2210/0004 bioabsorbable
• CPC Class Codes: A61L 27/18 obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: A61L 27/50 Materials characterised by their function or physical properties , e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
• CPC Class Codes: A61L 27/54 Biologically active materials, e.g. therapeutic substances A61L27/227 takes precedence
• CPC Class Codes: A61L 27/56 Porous materials, e.g. foams or sponges
• CPC Class Codes: A61L 27/58 Materials at least partially resorbable by the body
• CPC Class Codes: A61L 31/06 obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds A61L31/041 takes precedence
• CPC Class Codes: A61L 31/14 Materials characterised by their function or physical properties , e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
• CPC Class Codes: A61L 31/146 Porous materials, e.g. foams or sponges
• CPC Class Codes: A61L 31/148 Materials at least partially resorbable by the body
• CPC Class Codes: A61L 31/16 : Biologically active materials, e.g. therapeutic substances A61L31/047 takes precedence
• CPC Class Codes: C08L 67/04 : Polyesters derived from hydroxycarboxylic acids, e.g. lactones C08L67/06 takes precedence
• CPC Class Codes: Y10S 623/901 : Method of manufacturing prosthetic device
• CPC Class Codes: Y10S 623/902 : Method of implanting
• CPC Class Codes: Y10S 623/908 : Bone

Abstract

This invention provides molded, biodegradable porous polymeric implant materials having a pore size distribution throughout the material which is substantially uniform. These materials can be molded into implants of any desired size and shape without loss of uniformity of pore size distribution. The implants are useful as biodegradable scaffolds for cell growth in healing of tissue defects. When manufactured to have an aspect ratio greater than about 3, the implants can be further hand-shaped to fit the defect into which they are placed and the desired shape for the regrown tissue.

Claims

1. A method for making a molded biodegradable, porous polymeric implant material having a desired shape, wherein the pore size distribution throughout the material is substantially uniform, comprising:

a) preparing a precipitated gel-like polymer mass;

b) extracting liquid from the polymer mass;

c) kneading the polymer mass to form an extensible polymeric composition;

d) placing the extensible composition into a mold of the desired shape wherein the mold is perforated with spaced perforations to allow substantially uniform escape of gas during molding of the polymeric composition; and

e) treating the extensible composition in the mold in a vacuum oven at a temperature and time sufficient to cure the composition wherein a cured material having substantially uniform porosity is produced.

2. The method of claim 1 wherein the time and temperature of step e) are selected so as to produce a molded implant material having a Young'"'"'s modulus selected from a value between about 0.1 and about 50 MPa at room temperature.

3. A molded, porous, biodegradable material made by the method of claim 1.

4. The material of claim 3 wherein the material is in a sterilizable form of a cylinder having a volume between about 1 mm³ and about 16 mm³ having a largest cross-section diameter between about 1 mm and about 4 mm.

5. The cylinder of claim 4 having a Young'"'"'s modulus greater than about 1.0 MPa.

6. The method of claim 1 comprising using a polymer selected from the group consisting of polylactic acid (PLA), polyglycolic acid (PGA), and mixtures and copolymers thereof.

7. The method of claim 6 wherein said polymer is a 50:

50 copolymer of PLA/PGA.

8. The molded, porous, biodegradable material made by the method of claim 6.

9. The method of claim 6 wherein said cured material has the mechanical properties of cartilage, and step e) is conducted at about 37°

-42°

C. under vacuum for more than 24 hours.

10. The method of claim 9 wherein said cured material has the mechanical properties of bone, and step e) comprises a period of heating said material under vacuum to a temperature greater than 37°

-42°

C.