Claims
- 1. A method for treating the ultra-high molecular weight polyethylene material forming a medical implant, said material having a molecular weight greater than 400,000, the method comprising:
preventing said ultra-high molecular weight polyethylene material forming the implant from contact with oxygen in a concentration greater than 1% volume by volume; irradiating the polyethylene material forming said implant to create free radicals while said ultra-high molecular weight polyethylene material is prevented from contact with oxygen in a concentration greater than 1% volume by volume; and heating the polyethylene material forming the implant to form cross-links between said free radicals for a temperature and time at least equivalent to 50° C. for 144 hours as defined by Arrhennius' equation (14) while said ultra-high molecular weight polyethylene material is prevented from contact with oxygen in a concentration greater than 1% volume by volume.
- 2. The method as set forth in claim 1, wherein the contact with oxygen is prevented by sealing the polyethylene within an oxygen impermeable barrier.
- 3. The method as set forth in claim 2, wherein the oxygen impermeable barrier is a packaging material.
- 4. The method as set forth in claim 3, wherein the irradiating and heating are applied to a fully formed implant sealed within said packaging material.
- 5. The method as set forth in claim 1, wherein the temperature is greater than 25° C.
- 6. The method as set forth in claim 5, wherein the heating takes place for at least about four hours.
- 7. The method as set forth in claim 1, wherein the polyethylene material has a solubility of less than 74.7% in solvent after treatment.
- 8. The method as set forth in claim 1, wherein after treatment the polyethylene material has an oxidation index of 0.01 or less after oven aging in air at 80° C.
- 9. The method as set forth in claim 1, wherein the polyethylene material is heated to a temperature of between 25° C. and the melting point of said polymer.
- 10. The method as set forth in claim 1, wherein the polyethylene implant material is surrounded by a layer of material whose function is to prevent said polyethylene material from contact with oxygen, said layer of material is heated while surrounded by an oxygen containing atmosphere.
- 11. The method as set forth in claim 1, wherein the material forming the implant has less than 1.0×1017 residual free radicals per grams after said treatment to form cross-links.
- 12. A method for processing ultra-high molecular weight polyethylene having a molecular weight greater than 400,000 comprising:
creating free radicals in the polymer chain by irradiating the ultra-high molecular weight polyethylene; preventing oxygen from bonding with said created free radicals by preventing them from coming into contact with oxygen in a concentration greater than 1% volume by volume; and heating the polymer to create cross-links between free radicals prior to exposing the free radicals to oxygen above said concentration, said heating for a time and temperature at least equivalent to heating said polyethylene at 50° C. for 144 hours as defined by Arrhennius' equation (14).
- 13. The method as set forth in claim 12, wherein the contact with oxygen is prevented by sealing the polyethylene within an oxygen impermeable barrier.
- 14. The method as set forth in claim 12, wherein the oxygen impermeable barrier is a packaging material.
- 15. The method as set forth in claim 14, wherein the irradiating and heating are applied to a fully formed implant sealed within said packaging material.
- 16. The method as set forth in claim 12, wherein the temperature is greater than 25° C.
- 17. The method as set forth in claim 12, wherein the heating takes place for at least about four hours.
- 18. The method as set forth in claim 12, wherein the polyethylene material has a solubility of less than 74.7% in solvent after cross-linking.
- 19. The method as set forth in claim 12, wherein after cross-linking the polyethylene material has an oxidation index of 0.01 or less after oven aging in air at 80° C.
- 20. The method as set forth in claim 12, wherein the polyethylene material is heated to a temperature between 25° C. and the melting point of said polymer.
- 21. The method as set forth in claim 12, wherein the polyethylene is surrounded by a layer of material whose function is to prevent said polyethylene material from said contact with oxygen, said layer of material is heated while surrounded by an oxygen containing atmosphere.
- 22. The method as set forth in claim 12, wherein the polyethylene has less than 1.0×1017 residual free radicals per grams after said cross-linking.
- 23. An orthopedic implant comprising material processed according to the method of claim 12.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. Ser. No. 09/604,868 filed Jun. 28, 2000 which is a continuation of U.S. Ser. No. 09/012,345 filed Jan. 23, 1998, U.S. Pat. No. 6,174,934, which is a continuation of U.S. Ser. No. 733,067 filed Oct. 16, 1996, U.S. Pat. No. 5,728,748, which is a continuation of U.S. Ser. No. 439,028 filed May 11, 1995, U.S. Pat. No. 5,650,485, which is a division of U.S. Ser. No. 320,705 filed Oct. 7, 1994, U.S. Pat. No. 5,449,745 which is a division of U.S. Ser. No. 70,074 filed Jun. 1, 1993, U.S. Pat. No. 5,414,049.
Divisions (2)
|
Number |
Date |
Country |
Parent |
08320705 |
Oct 1994 |
US |
Child |
08439028 |
May 1995 |
US |
Parent |
08070074 |
Jun 1993 |
US |
Child |
08320705 |
Oct 1994 |
US |
Continuations (4)
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Number |
Date |
Country |
Parent |
09604868 |
Jun 2000 |
US |
Child |
10041118 |
Jan 2002 |
US |
Parent |
09012345 |
Jan 1998 |
US |
Child |
09604868 |
Jun 2000 |
US |
Parent |
08733067 |
Oct 1996 |
US |
Child |
09012345 |
Jan 1998 |
US |
Parent |
08439028 |
May 1995 |
US |
Child |
08733067 |
Oct 1996 |
US |