Shape-memory, biodegradable and absorbable material

• US 6,281,262 B1
• Filed: 11/12/1998
• Issued: 08/28/2001
• Est. Priority Date: 11/12/1998
• Status: Expired due to Term

• Current Assignee: Takiron Company Limited (Itochu Corporation)
• Original Assignee: Takiron Company Limited (Itochu Corporation)
• Inventors: Shikinami, Yasuo
• Primary Examiner(s): SZEKELY, PETER A
• Application Number:
  US09/189,973
• Time in Patent Office: 1,020 Days
• Field of Search: 523/105, 523/113, 523/115, 523/128, 524/600, 525/450, 623/22, 623/926, 264/230, 604/530
• US Class Current: 523/105
• CPC Class Codes: A61B 17/7059 Cortical plates A61B17/7007, A61B17/7058 take precedence
• CPC Class Codes: A61B 17/7275 with expanding cylindrical parts
• CPC Class Codes: A61B 17/846 Nails or pins, i.e. anchors without movable parts, holding by friction only, with or without structured surface A61B17/72, A61B17/86 take precedence
• CPC Class Codes: A61B 2017/00871 polymeric
• CPC Class Codes: A61F 2/30723 Plugs or restrictors for sealing a cement-receiving space tools for inserting plugs A61F2/4614; sealing collars for use during cementing A61B17/8808
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/34 Acetabular cups
• CPC Class Codes: A61F 2/3662 Femoral shafts
• CPC Class Codes: A61F 2002/30065 thermoplastic, i.e. softening or fusing when heated, and hardening and becoming rigid again when cooled
• CPC Class Codes: A61F 2002/30067 Coating or prosthesis-covering structure made of thermoplastic material
• CPC Class Codes: A61F 2002/30077 shrinkable
• CPC Class Codes: A61F 2002/30092 using shape memory or superelastic materials, e.g. nitinol
• CPC Class Codes: A61F 2002/3092 having an open-celled or open-pored structure
• CPC Class Codes: A61L 17/12 Homopolymers or copolymers of glycolic acid or lactic acid
• CPC Class Codes: A61L 2400/16 Materials with shape-memory or superelastic properties
• 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: C08L 67/04 Polyesters derived from hydroxycarboxylic acids, e.g. lactones C08L67/06 takes precedence
• CPC Class Codes: Y10S 623/926 Synthetic

Abstract

Shape-memory biodegradable and absorbable materials which make it possible to easily treat vital tissues by suture, anastomosis, ligation, fixation, reconstitution, prosthesis, etc. without causing burn. These materials never induce halation in MRI or CT and never remain in vivo. Such a shape-memory biodegradable and absorbable material is a material made of a molded article of lactic acid-based polymer and can be recovered to the original shape without applying any external force thereto but heating to a definite temperature or above. It is obtained by deforming a molded article (a primary molded article) made of a lactic acid-based polymer and having a definite shape into another molded article (a secondary molded article) having another shape at a temperature higher than the glass transition temperature thereof but lower than the crystallization temperature thereof (or 100° C. when the molded article has no crystallization temperature) and then fixing said molded article to the thus deformed shape by cooling it as such to a temperature lower than the glass transition temperature. When this material is heated to the above-mentioned deformation temperature or above, it is immediately recovered to the original shape. The lactic acid-based polymer is hydrolyzed and absorbed in vivo.

Claims

1. A shape-memory biodegradable and absorbable article which comprises a biodegradable and absorbable article prepared by deforming a molded article of a copolymer obtained by ring-opening polymerization of about a 1:

1 molar mixture of L-lactide and D-lactide and having a definite original shape into another molded article having another shape at a deformation temperature higher than the glass transition temperature thereof but lower than the crystallization temperature thereof (or 100°

C. when the molded article has no crystallization temperature) and then fixing said molded article to the thus deformed shape by cooling it as such to a temperature lower than the glass transition temperature, wherein said molded article can be recovered to the molded article of the original shape by heating it again to said deformation temperature or above.

24. The shape-memory biodegradable and absorbable material as claimed in claim 1, which further comprises a bioceramics powder.

25. The shape-memory biodegradable and absorbable material as claimed in claim 24, wherein said bioceramics powder is a least one member selected from the group consisting of surface bioactive sintered hydroxyapatite, bioglass for living body use, crystallized glass for living body use, bioabsorbable neither calcined nor sintered hydroxyapatite, dicalcium phosphate, tricalcium phosphate, tetracalcium phosphate, octacalcium phosphate, calcite and diopsite.

26. The shape-memory biodegradable and absorbable material as claimed in claim 1, which further comprises a drug.

2. A shape-memory biodegradable and absorbable article which comprises a biodegradable and absorbable article prepared by deforming a molded article of a copolymer obtained by ring-opening polymerization of DL (meso)-lactide and having a definite original shape into another molded article having another shape at a deformation temperature higher than the glass transition temperature thereof but lower than the crystallization temperature thereof (or 100°

C. when the molded article has no crystallization temperature) and then fixing said molded article to the thus deformed shape by cooling it as such to a temperature lower than the glass transition temperature, wherein said molded article can be recovered to the molded article of the original shape.

3. A shape-memory biodegradable and absorbable article which comprises a biodegradable and absorbable article prepared by deforming a first molded article of a lactic acid polymer and having a definite original shape into another molded article having another shape at a first deformation temperature higher than the glass transition temperature thereof but lower than the crystallization temperature thereof (or 100°

C. when the molded article has no crystallization temperature), then fixing said molded article to the thus deformed shape by cooling it as such to a temperature lower than the glass transition temperature, further deforming said molded article into another molded article having another shape at a second deformation temperature higher than the glass transition temperature but lower than said first deformation temperature and fixing said molded article to the thus deformed shape by cooling it as such to a temperature lower than the glass transition temperature, wherein said molded article can be recovered to the first molded article of the original shape by heating it again to the first deformation temperature or above.

4. A shape biodegradable and absorbable article which comprises a biodegradable and absorbable article prepared by deforming a porous molded article of a lactic acid polymer and having a definite original shape into a substantially non-porous molded article having another shape at a deformation temperature higher than the glass transition temperature thereof but lower than the crystallization temperature thereof (or 100°

C. when the molded article has no crystallization temperature) and then fixing said molded article to the thus deformed shape by cooling it as such to a temperature lower than the glass transition temperature, wherein said molded article can be recovered to the porous molded article of the original shape by heating it again to said deformation temperature or above.

5. A shape-memory biodegradable and absorbable article for vascular anastomosis which comprises a molded article of a lactic acid polymer in the shape of large diameter pipes, wherein said molded article can be recovered to a memorized shape of small diameter pipes without applying any external force thereto but by heating to a definite temperature or above.

27. A shape-memory biodegradable and absorbable article according to claim 5, wherein the lactic acid polymer is a copolymer obtained by ring opening polymerization of about a 1:

1 molar mixture of L-lactide and D-lactide or a copolymer obtained by ring-opening polymerization of DL(meso)-lactide.

6. A shape-memory biodegradable and absorbable article for vascular anastomosis which comprises a biodegradable and absorbable material prepared by enlarging and deforming a molded article of a lactic acid polymer in the shape of small diameter pipes into another molded article in the shape of large diameter pipes at a deformation temperature higher than the glass transition temperature thereof but lower than the crystallization temperature thereof (or 100°

C. when the molded article has no crystallization temperature) and then fixing said molded article to the shape of large diameter pipes by cooling it as such to a temperature lower than the glass transition temperature, wherein said molded article can be recovered to the molded article in the shape of small diameter pipes by heating it again to said deformation temperature or above.

28. A shape-memory biodegradable and absorbable article according to claim 6, wherein the lactic acid polymer is a copolymer obtained by ring opening polymerization of about a 1:

1 molar mixture of L-lactide and D-lactide or a copolymer obtained by ring-opening polymerization of DL(meso)-lactide.

7. A shape-memory biodegradable and absorbable article for vascular ligation which comprises a molded article of a lactic acid polymer in the shape of large diameter rings, wherein said article can be recovered to a memorized shape of small diameter rings without applying any external force thereto but by heating to a definite temperature or above.

29. A shape-memory biodegradable and absorbable article according to claim 7, wherein the lactic acid polymer is a copolymer obtained by ring opening polymerization of about a 1:

1 molar mixture of L-lactide and D-lactide or a copolymer obtained by ring-opening polymerization of DL(meso)-lactide.

8. A shape-memory biodegradable and absorbable article for vascular ligation which comprises a biodegradable and absorbable material prepared by enlarging and deforming a molded article of a lactic acid polymer in the shape of small diameter rings into another molded article in the shape of large diameter rings at a deformation temperature higher than the glass transition temperature thereof but lower than the crystallization temperature thereof (or 100°

C. when the molded article has no crystallization temperature) and then fixing said molded article to the shape of large diameter rings by cooling it as such to a temperature lower than the glass transition temperature followed by cutting into round slices, wherein said molded article can be recovered to the molded article in the shape of small diameter rings cut into round slices by heating it again to said deformation temperature or above.

30. A shape-memory biodegradable and absorbable article according to claim 8, wherein the lactic acid polymer is a copolymer obtained by ring opening polymerization of about a 1:

1 molar mixture of L-lactide and D-lactide or a copolymer obtained by ring-opening polymerization of DL(meso)-lactide.

9. A shape-memory biodegradable and absorbable article for vascular ligation which comprises a biodegradable and absorbable material prepared by enlarging and deforming a molded article of a lactic acid polymer in the shape of small diameter rings into another molded article in the shape of large diameter rings at a deformation temperature higher than the glass transition temperature thereof but lower than the crystallization temperature thereof (or 100°

C. when the molded article has no crystallization temperature) and then fixing said molded article to the shape of large diameter rings by cooling it as such to a temperature lower than the glass transition temperature, wherein said molded article can be recovered to the molded article in the shape of small diameter rings by heating it again to said deformation temperature or above.

31. A shape-memory biodegradable and absorbable article according to claim 9, wherein the lactic acid polymer is a copolymer obtained by ring opening polymerization of about a 1:

1 molar mixture of L-lactide and D-lactide or a copolymer obtained by ring-opening polymerization of DL(meso)-lactide.

10. A shape-memory biodegradable and absorbable article for tendon fixation which comprises a biodegradable and absorbable material prepared by enlarging and deforming a molded article of a lactic acid polymer in the shape of almost square small pipes having a flat opening area into another molded article in the shape of almost square large pipes having a large opening area at a deformation temperature higher than the glass transition temperature thereof but lower than the crystallization temperature thereof (or 100°

C. when the molded article has no crystallization temperature) and then fixing said molded article to the shape of almost square large pipes having a large opening area by cooling it as such to a temperature lower than the glass transition temperature, wherein said molded article can be recovered to the molded article in the shape of almost square small pipes having a flat opening area by heating it again to said deformation temperature or above.

32. A shape-memory biodegradable and absorbable article according to claim 10, wherein the lactic acid polymer is a copolymer obtained by ring opening polymerization of about a 1:

1 molar mixture of L-lactide and D-lactide or a copolymer obtained by ring-opening polymerization of DL(meso)-lactide.

11. A shape-memory biodegradable and absorbable article for suture which comprises a molded article of a lactic acid polymer in the shape of large diameter opened-out rings, wherein said article can be recovered to an original shape of small diameter rings without applying any external force thereto but by heating to a definite temperature or above.

33. A shape-memory biodegradable and absorbable article according to claim 11, wherein the lactic acid polymer is a copolymer obtained by ring opening polymerization of about a 1:

1 molar mixture of L-lactide and D-lactide or a copolymer obtained by ring-opening polymerization of DL(meso)-lactide.

12. A shape-memory biodegradable and absorbable article for suture which comprises a biodegradable and absorbable material prepared by enlarging and deforming a molded article of a lactic acid polymer in the shape of small diameter rings into another molded article in the shape of large diameter rings at a deformation temperature higher than the glass transition temperature thereof but lower than the crystallization temperature thereof (or 100°

C. when the molded article has no crystallization temperature) and then fixing said molded article to the shape of large diameter rings by cooling it as such to a temperature lower than the glass transition temperature followed by opening-out, wherein said molded article can be recovered to the molded article in the shape of small diameter rings having been opened-out by heating it again to said deformation temperature or above.

34. A shape-memory biodegradable and absorbable article according to claim 12, wherein the lactic acid polymer is a copolymer obtained by ring opening polymerization of about a 1:

1 molar mixture of L-lactide and D-lactide or a copolymer obtained by ring-opening polymerization of DL(meso)-lactide.

13. A shape-memory biodegradable and absorbable article for suture which comprises a biodegradable and absorbable material prepared by enlarging and deforming a molded article of a lactic acid polymer in the shape of small diameter rings into another molded article in the shape of large diameter rings at a deformation temperature higher than the glass transition temperature thereof but lower than the crystallization temperature thereof (or 100°

C. when the molded article has no crystallization temperature), opening-out said molded article in the shape of large diameter rings, bending a part of the same so as to match with a suture needle, and then fixing said molded article to the shape by cooling it as such to a temperature lower than the glass transition temperature, wherein said molded article can be recovered to the molded article in the shape of small diameter rings having been opened-out by heating it again to said deformation temperature or above.

35. A shape-memory biodegradable and absorbable article according to claim 13, wherein the lactic acid polymer is a copolymer obtained by ring opening polymerization of about a 1:

1 molar mixture of L-lactide and D-lactide or a copolymer obtained by ring-opening polymerization of DL(meso)-lactide.

14. A shape-memory biodegradable and absorbable article for suture which comprises a molded article of a lactic acid polymer in the shape of thin yarns wherein said material can be recovered into the shape of thick yarns without applying any external force thereto but by heating to a definite temperature or above.

36. A shape-memory biodegradable and absorbable article according to claim 14, wherein the lactic acid polymer is a copolymer obtained by ring opening polymerization of about a 1:

1 molar mixture of L-lactide and D-lactide or a copolymer obtained by ring-opening polymerization of DL(meso)-lactide.

15. A shape-memory biodegradable and absorbable article for suture which comprises a biodegradable and absorbable material prepared by drawing and deforming a molded article of a lactic acid polymer in the shape of short, thick yarns into another molded article in the shape of yarns longer and thinner than said ones at a deformation temperature higher than the glass transition temperature thereof but lower than the crystallization temperature thereof (or 100°

C. when the molded article has no crystallization temperature) and then fixing said molded article to the shape of thin yarns by cooling it as such to a temperature lower than the glass transition temperature, wherein said molded article can be shortened and thus recovered to the molded article in the shape of short, thick yarns by heating it again to said deformation temperature or above.

37. A shape-memory biodegradable and absorbable article according to claim 15, wherein the lactic acid polymer is a copolymer obtained by ring opening polymerization of about a 1:

1 molar mixture of L-lactide and D-lactide or a copolymer obtained by ring-opening polymerization of DL(meso)-lactide.

16. A shape-memory biodegradable and absorbable article for bone fixation which comprises a molded article of a lactic acid polymer in the shape of thin bars wherein said material can be recovered to an original shape in the shape of thick and round bar without applying any external force thereto but by heating to a definite temperature or above.

38. A shape-memory biodegradable and absorbable article according to claim 16, wherein the lactic acid polymer is a copolymer obtained by ring opening polymerization of about a 1:

1 molar mixture of L-lactide and D-lactide or a copolymer obtained by ring-opening polymerization of DL(meso)-lactide.

17. A shape-memory biodegradable and absorbable article for bone fixation which comprises a biodegradable and absorbable material prepared by deforming a molded article of a lactic acid polymer in the shape of short, thick bars into another molded article in the shape of bars longer and thinner than said ones at a deformation temperature higher than the glass transition temperature thereof but lower than the crystallization temperature thereof (or 100°

C. when the molded article has no crystallization temperature) and then fixing said molded article to the shape of thin bars by cooling it as such to a temperature lower than the glass transition temperature, wherein said molded article can be recovered to the molded article in the shape of short, thick bars by heating it again to said deformation temperature or above.

18. The shape-memory biodegradable and absorbable article as claimed in claim 17, wherein said deformed molded article in the shape of long and thin bars is fixed to the shape by cooling and then cut into definite pins.

39. A shape-memory biodegradable and absorbable article according to claim 17, wherein the lactic acid polymer is a copolymer obtained by ring opening polymerization of about a 1:

1 molar mixture of L-lactide and D-lactide or a copolymer obtained by ring-opening polymerization of DL(meso)-lactide.

40. A shape-memory biodegradable and absorbable article according to claim 18, wherein the lactic acid polymer is a copolymer obtained by ring opening polymerization of about a 1:

1 molar mixture of L-lactide and D-lactide or a copolymer obtained by ring-opening polymerization of DL(meso)-lactide.

19. A shape-memory biodegradable and absorbable article for bone fixation which comprises a biodegradable and absorbable material prepared by deforming a molded article of a lactic acid polymer in an original shape of a cylinder provided with two or more inclined arms projecting from the peripheries of both ends thereof at a deformation temperature higher than the glass transition temperature thereof but lower than the crystallization temperature thereof (or 100°

C. when the molded article has no crystallization temperature) so that each arm is bent inside at the base in parallel to the axis of the cylinder and then fixing said molded article to said shape by cooling it as such to a temperature lower than the glass transition temperature, wherein said molded article can be recovered to an original shape by heating it again to said deformation temperature or above.

41. A shape-memory biodegradable and absorbable article according to claim 19, wherein the lactic acid polymer is a copolymer obtained by ring opening polymerization of about a 1:

1 molar mixture of L-lactide and D-lactide or a copolymer obtained by ring-opening polymerization of DL(meso)-lactide.

20. A shape-memory biodegradable and absorbable article for preventing bone cement in marrow cavity from leakage which comprises a biodegradable and absorbable material prepared by deforming a molded article of a lactic acid polymer in an original shape of a cylindrical plug having a hemispherical bottom and provided with two or more petal-shaped inclined projections extended from the periphery of the upper face thereof at a deformation temperature higher than the glass transition temperature thereof but lower than the crystallization temperature thereof (or 100°

C. when the molded article has no crystallization temperature) so that each petal-shaped projection is bent inside at the base in parallel to the axis of the cylinder and then fixing said molded article to said shape by cooling it as such to a temperature lower than the glass transition temperature, wherein said molded article can be recovered to the original shape by heating it again to said deformation temperature or above.

42. A shape-memory biodegradable and absorbable article according to claim 20, wherein the lactic acid polymer is a copolymer obtained by ring opening polymerization of about a 1:

1 molar mixture of L-lactide and D-lactide or a copolymer obtained by ring-opening polymerization of DL(meso)-lactide.

21. A shape-memory biodegradable and absorbable article for preventing vascular reconstriction which comprises a biodegradable and absorbable material prepared by deforming a molded article of a lactic acid polymer in an original shape of a perforated cylinder with a number of pores or a net or mesh cylinder into another molded article in the shape of a folded cylinder at a deformation temperature higher than the glass transition temperature thereof but lower than the crystallization temperature thereof (or 100°

C. when the molded article has no crystallization temperature) and then fixing said molded article to said shape by cooling it as such to a temperature lower than the glass transition temperature, wherein said molded article can be recovered to the original shape by heating it again to said deformation temperature or above.

43. A shape-memory biodegradable and absorbable article according to claim 21, wherein the lactic acid polymer is a copolymer obtained by ring opening polymerization of about a 1:

1 molar mixture of L-lactide and D-lactide or a copolymer obtained by ring-opening polymerization of DL(meso)-lactide.

22. A shape-memory biodegradable and absorbable article for an artificial hip joint comprising a molded article of a copolymer obtained by ring-opening polymerization of about a 1:

1 mixture of L-lactide and D-lactide in a hemisphere cup shape, wherein said article can be recovered to a memorized shape of a small hemisphere cup shape without applying any external force thereto but by heating to a definite temperature or above.

23. A shape-memory biodegradable and absorbable article for an artificial hip joint which comprises a biodegradable and absorbable article prepared by enlarging and deforming a molded article of a copolymer obtained by ring-opening polymerization of DL (meso)-lactide in the shape of a small hemisphere cup shape into another molded article in the shape of a large hemisphere cup shape at a deformation temperature higher than the glass transition temperature thereof but lower than the crystallization temperature thereof (or 100°

C. when the molded article has no crystallization temperature) and then fixing said molded article to the shape of the large hemisphere cup shape by cooling it as such to a temperature lower than the glass transition temperature, wherein said molded article can be recovered to the molded article in the shape of the small hemisphere cup shape by heating it again to said deformation temperature or above.

44. A shape-memory biodegradable and absorbable article for an artificial hip joint comprising a molded article of a lactic acid polymer in a hemisphere cup shape, wherein said article can be recovered to a memorized shape of a small hemisphere cup shape without applying any external force thereto but by heating to a definite temperature or above.

45. The shape-memory article according to claim 44, wherein the lactic acid polymer is a copolymer obtained by ring-opening polymerization of DL(meso)-lactide.

46. A shape-memory biodegradable and absorbable article for hip joint which comprises a biodegradable and absorbable article prepared by enlarging and deforming a molded article of a lactic acid polymer in the shape of a small hemisphere cup shape into another molded article in the shape of a large hemisphere cup shape at a deformation temperature higher than the glass transition temperature thereof but lower than the crystallization temperature thereof (or 100°

C. when the molded article has no crystallization temperature) and then fixing said molded article to the shape of the large hemisphere cup shape by cooling it as such to a temperature lower than the glass transition temperature, wherein said molded article can be recovered to the molded article in the shape of the small hemisphere cup shape by heating it again to said deformation temperature or above.

47. The shape memory article according to claim 46, wherein the lactic acid polymer is a copolymer obtained by ring-opening polymerization of about a 1:

1 mixture of L-lactide and D-lactide.