ANTIOXIDANT-STABILIZED JOINT IMPLANTS

• US 20150151866A1
• Filed: 05/09/2013
• Published: 06/04/2015
• Est. Priority Date: 05/11/2012
• Status: Active Grant

• Current Assignee: The General Hospital Corporation (Mass General Brigham, Inc.)
• Original Assignee: The General Hospital Corporation (Mass General Brigham, Inc.)
• Inventors: Oral, Ebru, Muratoglu, Orhun
• Granted Patent: US 10,000,305 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61F 2/30 Joints
• CPC Class Codes: A61F 2240/001 Designing or manufacturing processes
• CPC Class Codes: A61L 2300/428 Vitamins, e.g. tocopherol, riboflavin
• CPC Class Codes: A61L 27/16 obtained 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: B29C 2035/0877 using electron radiation, e.g. beta-rays
• CPC Class Codes: B29C 2071/0027 Removing undesirable residual components, e.g. solvents, unreacted monomers of material to be shaped B29B9/16, B29B13/00
• CPC Class Codes: B29C 2071/022 Annealing
• CPC Class Codes: B29C 71/0009 using liquids, e.g. solvents, swelling agents spectacle cases, e.g. for cleaning contact lenses A45C11/04; disinfecting or sterilising contact lenses A61L12/00, using liquid substances A61L2/20; cleaning involving the use of liquid in general B08B3/00; for hydrating contact lenses B29D11/00067
• CPC Class Codes: B29C 71/02 Thermal after-treatment B29C71/0063 and B29C71/0072 take precedence
• CPC Class Codes: B29C 71/04 by wave energy or particle radiation , e.g. for curing or vulcanising preformed articles during moulding, e.g. in a mould B29C35/08
• CPC Class Codes: B65B 55/16 by irradiation
• CPC Class Codes: C08J 2323/06 Polyethene
• CPC Class Codes: C08J 7/123 Treatment by wave energy or particle radiation C08J7/18 takes precedence
• CPC Class Codes: C08L 2207/068 Ultra high molecular weight polyethylene
• CPC Class Codes: C08L 23/06 Polyethene

Abstract

Methods of making a wear and oxidation resistant medical implant are disclosed.

Claims

1. A method of making a wear and oxidation resistant medical implant, the method comprising:

(a) blending a polymeric material with one or more antioxidant(s);

(b) consolidating the blended polymeric material into a medical implant preform;

(c) irradiating the medical implant preform with low energy electrons at below 2 MeV with the desired surfaces exposed to the beam;

(d) machining the medical implant preform into a medical implant; and

(e) packaging and sterilizing the medical implant.

2. The method of claim 1 wherein step (c) comprises irradiating the medical implant preform with an electron scattering device comprising fibers in contact with or close to the surface to be irradiated.

3. The method of claim 1 further comprising annealing the medical implant preform after step (c).

11. The method of claim 1, wherein the antioxidant used in blending in step (a) is vitamin E.

12. The method according to claim 1, wherein the material is pre-heated to an elevated temperature before irradiation such that the material is irradiated between 100°

C. and 130°

C.

13. The method according to claim 1, wherein the antioxidant concentration in the blend is 0.1 wt % to 5 wt %.

16. The method according to claim 1, wherein the irradiation is an electron beam irradiation.

17. The method according to claim 1, wherein the irradiation dose is in the range of about 25 kGy to about 150 kGy.

20. The method according to claim 1, wherein the radiation dose rate is between about 1 kGy/pass to 50 kGy/pass.

22. The method according to claim 1, wherein the electron beam energy is between about 1 and 4 MeV.

24. The method according to claim 1, wherein the sterilization is a gamma sterilization.

25. The method according to claim 1, wherein step (c) comprises irradiating the medical implant preform with an electron scattering device comprising metallic fibers.

26. The method according to claim 1, wherein step (c) comprises irradiating the medical implant preform with an electron scattering device comprising metallic wool.

27. The method according to claim 1, wherein step (c) comprises irradiating the medical implant preform with an electron scattering device comprising metallic brushes.

28. The method according to claim 1, wherein step (c) comprises irradiating the medical implant preform with an electron scattering device situated within a millimeter of intended surfaces to be irradiated.

29. The method according to claim 1, wherein step (c) comprises irradiating the medical implant preform with an electron scattering device situated within thirty centimeters of intended surfaces to be irradiated.

30. The method according to claim 1, wherein the polymeric materials comprises ultrahigh molecular weight polyethylene, and the antioxidant used in step (a) is vitamin E.

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31. A method of making a wear and oxidation resistant medical implant, the method comprising:

(a) blending a polymeric material with one or more antioxidant(s);

(b) consolidating the blended polymeric material into a medical implant;

(c) irradiating the medical implant preform with low energy electrons at below 2 MeV with desired surfaces exposed to a beam with an electron scattering device; and

(d) packaging and sterilizing the medical implant.

32. The method of claim 31 wherein the electron scattering device comprises fibers in contact with or close to the surface to be irradiated.

33. The method of claim 31 further comprising annealing the medical implant preform after step (c).

34. The method of claim 31, wherein the antioxidant used in blending in step (a) is vitamin E.

35. The method according to claim 31, wherein the material is pre-heated to an elevated temperature before irradiation such that the material is irradiated between 100°

C. and 130°

C.

36. The method according to claim 31, wherein the antioxidant concentration in the blend is 0.1 wt % to 5 wt %.

37. The method according to claim 31, wherein the irradiation is an electron beam irradiation.

38. The method according to claim 31, wherein the irradiation dose is in the range of about 25 kGy to about 150 kGy.

39. The method according to claim 31, wherein the radiation dose rate is between about 1 kGy/pass to 50 kGy/pass.

40. The method according to claim 31, wherein the electron beam energy is between about 1 and 4 MeV.

41. The method according to claim 31, wherein the sterilization is a gamma sterilization.

42. The method according to claim 31, wherein the electron scattering device comprises metallic fibers or metallic wool or metallic brushes.

43. The method according to claim 31, wherein the electron scattering device is situated within a millimeter of intended surfaces to be irradiated.

44. The method according to claim 31, wherein the electron scattering device is situated within thirty centimeters of intended surfaces to be irradiated.

45. The method according to claim 31, wherein the polymeric materials comprises ultrahigh molecular weight polyethylene, and the antioxidant used in step (a) is vitamin E.

46. A method of making a wear and oxidation resistant medical implant, the method comprising:

(a) blending a polymeric material with one or more antioxidant(s);

(b) consolidating the blended polymeric material into a medical implant preform;

(c) irradiating the medical implant preform with low energy electrons at below 2 MeV with desired surfaces exposed to the beam;

(d) doping the medical implant preform with one or more antioxidant(s); and

(e) machining the medical implant preform into a medical implant.

47. The method of claim 46 wherein step (c) comprises irradiating the medical implant preform with an electron scattering device comprising fibers in contact with or close to the surface to be irradiated.

48. The method of claim 46 further comprising annealing the medical implant preform after step (c).

49. The method of claim 46, wherein the antioxidant used in blending in step (a) and doping in step (d) is vitamin E.

50. The method according to claim 46, wherein the material is pre-heated to an elevated temperature before irradiation such that the material is irradiated between 100°

C. and 130°

C.

51. The method according to claim 46, wherein the antioxidant concentration in the blend is 0.1 wt % to 5 wt %.

52. The method according to claim 46, wherein the irradiation is an electron beam irradiation.

53. The method according to claim 46, wherein the irradiation dose is in the range of about 25 kGy to about 150 kGy.

54. The method according to claim 46, wherein the radiation dose rate is between about 1 kGy/pass to 50 kGy/pass.

55. The method according to claim 46, wherein the electron beam energy is between about 1 and 4 MeV.

56. The method according to claim 47, wherein the electron scattering device comprises metallic fibers or metallic wool or metallic brushes.

57. The method according to claim 47, wherein the electron scattering device is situated within a millimeter of intended surfaces to be irradiated.

58. The method according to claim 47, wherein the electron scattering device is situated within thirty centimeters of intended surfaces to be irradiated.

59. The method according to claim 46, wherein the polymeric materials comprises ultrahigh molecular weight polyethylene, and the antioxidant used in step (a) is vitamin E.