Bioabsorbable materials and medical devices made therefrom

• US 6,716,957 B2
• Filed: 01/08/2001
• Issued: 04/06/2004
• Est. Priority Date: 03/05/1999
• Status: Expired due to Term

• Current Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Original Assignee: Stryker Technologies Corporation
• Inventors: Tunc, Deger C.
• Primary Examiner(s): Truong, Duc
• Application Number:
  US09/756,589
• Publication Number:
  US 20010012940A1
• Time in Patent Office: 1,184 Days
• Field of Search: 528/354, 525/462, 525/461, 525/413, 525/415, 525/469, 606/77, 606/73, 606/154, 623/23.75
• US Class Current: 528/354
• CPC Class Codes: A61B 17/80 Cortical plates , i.e. bone plates; Instruments for holding or positioning cortical plates, or for compressing bones attached to cortical plates
• 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: C08L 67/04 Polyesters derived from hydroxycarboxylic acids, e.g. lactones C08L67/06 takes precedence
• CPC Class Codes: Y10S 606/91 Polymer

Abstract

A bioabsorbable material such as a terpolymer of poly-(L-lactide/D-lactide/glycolide). The material may consist of 85 molar percent L-lactide, 5 molar percent D-lactide, and 10 molar percent glycolide. The material may have a heat of fusion of about 15-25 J/G, tensile strength retention at 26 weeks of incubation of at least about 50%, and tensile strength retention at 52 weeks of incubation of at most about 25%. The material may be used in implantable devices such as bone fixation devices.

Claims

1. A material comprising a terpolymer having repeating units of L-lactide, D-lactide and glycolide.

2. The material as set forth in claim 1 comprising at least about 2 molar percent D-lactide.

3. The material as set forth in claim 2 comprising at least about 4 molar percent D-lactide.

4. The material as set forth in claim 3 comprising about 2 to about 10 molar percent D-lactide.

5. The material as set forth in claim 4 comprising about 80-90 molar percent L-lactide, about 2-10 molar percent D-lactide, and about 5-15 molar percent glycolide.

6. The material as set forth in claim 5 comprising about 83-87 molar percent L-lactide, about 3-7 percent D-lactide, and about 8-12 molar percent glycolide.

7. The material as set forth in claim 6 consisting essentially of 85 molar percent L-lactide, 5 molar percent D-lactide, and 10 molar percent glycolide.

8. The material as set forth an claim 1 further comprising about 0.1-5 molar percent of a polymer formed from alpha-hydroxy-alpha-ethylbutyric acid;

alpha-hydroxy-beta-methylvaleric acid;

alpha-hydroxyacetic acid;

alpha-hydroxybutyric acid;

alpha-hydroxycaproic acid;

alpha-hydroxydecanoic acid;

alpha-hydroxyheptanoic acid;

alpha-hydroxyisobutyric acid;

alpha-hydroxyisocaproic acid;

alpha-hydroxyisovaleric acid;

alpha-hydroxymyristic acid;

alpha-hydroxyoctanoic acid;

alpha-hydroxystearic acid;

alpha-hydroxyvaleric acid;

beta-butyrolactone;

beta-propiolactide;

gamma-butyrolactone pivalolactone;

or tetramethylglycolide or combinations thereof.

9. The material as set forth in claim 1 made by the process comprising:

a) combining L-lactic acid monomer, glycolic acid monomer and at least about 2 molar percent D-lactic acid monomer to form a mixture; and

b) polymerizing substantially all of the mixture.

10. The process of claim 9 wherein the polymerization is performed in the presence of a catalyst.

11. The process of claim 10 wherein the polymerization is performed for between 24 and 72 hours.

12. The material as set forth in claim 1 wherein the polymer has a heat of fusion of about 0.4-10 J/G, tensile strength retention at 52 weeks of incubation of at most about 25%.

13. The material as set forth in claim 1 wherein the polymer has a tensile strength at 0 weeks of incubation in buffered saline at 37°

C. of about 65-101 MPa, tensile strength at 26 weeks of incubation of about 50-75 MPa, and tensile strength at 52 weeks of incubation of 0 MPa.

14. The medical device as set forth in claim 1 wherein the polymer has a bending strength of at least 120 MPa at 0 weeks incubation in buffered saline at 37°

C., at least 110 at 4 weeks incubation, at least 110 at 8 weeks incubation, at least 70 at 12 weeks incubation and at least 45 at 26 weeks incubation.

15. The material of claim 1 having a heat of fusion of about 0.4-10 J/G.

16. The material of claim 15 having a heat of fusion of about 0.5—

5 J/G.

17. The material of claim 16 formed from a resin having a heat of fusion of about 15-25 J/G.

18. The material of claim 17 formed from a resin having a heat of fusion of about 18-21 J/G.

19. The material of claim 18 having tensile strength at 0 weeks of incubation in buffered saline at 37°

C. of about 74-92 MPa, tensile strength at 26 weeks of incubation of about 56-69 MPa, and tensile strength at 52 weeks incubation of about 0 MPa.

20. The medical device as sec forth in claim 1 wherein the polymer has an inherent viscosity between about 4.0 and 7.5 dl/g.

21. The medical device as set forth in claim 20 wherein the polymer has an inherent viscosity of between about 6.0 and 6.5 dl/g.

22. A material comprising a polymer having repeating units depicted by the formula:

where the molar percentages of the repeating units are;

80<

n<

90

2<

p<

10

5<

q<

15.

23. The medical devices as set forth in claim 22 wherein the polymer further comprises about 0.1-5 molar percent of a polymer formed from alpha-hydroxy-alpha-ethylbutyric acid;

alpha-hydroxy-beta-methylvaleric acid;

alpha-hydroxyacetic acid;

alpha-hyrdoxybutyric acid;

alpha-hydroxycaproic acid;

alpha-hydroxydecanoic acid;

alpha-hydroxyheptanoic acid;

alpha-hydroxyisobutyric acid;

alpha-hydroxyisocaproic acid;

alpha-hydroxyisovaleric acid;

alpha-hydroxymyristic acid;

alpha-hydroxyocantoic acid;

alpha-hydroxystearic acid;

alpha-hydroxyvaleric acid;

beta-batyrolactone;

beta-propiolactide;

gamma-butyrolactone;

pivalolactone or tetramethylglycolide;

or combinations thereof.

24. The medical device as set forth in claim 22 comprising at least about 4 molar percent D-lactide.

25. The medical device as set forth in claim 22 comprising about 83-87 molar percent L-lactide, about 3-7 percent D-lactide, and about 8-12 molar percent glycolide.

26. The medical device as set forth in claim 25 consisting essentially of 85 molar percent L-lactide, 5 molar percent D-lactide, and 10 molar percent glycolide.

27. The medical device as set forth in claim 22 wherein the polymer has a tensile strength at 0 weeks of incubation in buffered saline at 37°

C. of about 65-101 MPa, tensile strength at 26 weeks of incubation of about 50-75 MPa and tensile strength at 52 weeks of incubation at 0 MPa.

28. The medical device as set forth in claim 22 wherein the polymer has a bending strength of at least 120 MPa at 0 weeks incubation in buffered saline at 37°

C., at least 110 at 4 weeks, at least 110 at 8 weeks, at least 70 at 12 weeks and at least 45 at 26 weeks incubation.

29. The material of claim 22 having a heat fusion of about 0.4-10 J/G.

30. The material of claim 22 having a heat fusion of about 0.5—

5 J/G.

31. The material of claim 22 formed from a resin having a heat of fusion of about 15-25 J/G.

32. The material of claim 22 formed from a resin having a heat of fusion of about 18-21 J/G.

33. The medical device as set forth in claim 22 wherein the polymer has an inherent viscosity between about 4.0 and 7.5 dl/g.