Patent US5449745A successfully refreshed from Google Patents.
US5449745A
Expired / Lapsed
US
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Non-oxidizing polymeric medical implant
Assignee: Howmedica Osteonics Corp
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Filing: 1994-10-07
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Granted: 1995-09-12
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Expires: 2014-10-07
Abstract
Abstract A medical implant made of polymeric material having an increased oxidation resistance is formed by a method including the steps of placing a resin powder in a sealed container. A substantial portion of the oxygen is removed from the sealed container by either a vacuum, an oxygen absorbent or by flushing with inert gas. The container is then repressurized with a gas such as nitrogen, argon, helium or neon so that long term storage may be possible. On use, the resin is transferred to a forming device which both melts and forms the resin in an oxygen reduced atmosphere to produce a polymeric raw material such as a rod or bar stock. The medical implant is then formed from this raw material annealed and sealed in an air-tight package in an oxygen reduced atmosphere. The implant is then radiation sterilized and thereafter annealed in the package for a predetermined time and temperature sufficient to form cross-links between any free radicals in neighboring polymeric chains.
Inventors
- 👤 Deh-Chuan Sun
- 👤 Casper F. Stark
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 15:37
CPC Classifications
A; A61; A61L; A61L2/00; A61L2/02; A61L2/08; A61L2/081; A61L15/00; A61L15/16; A61L15/42; A61L15/60; A61L2/082; A61L2/087; A61L27/00; A61L27/14; A61L27/16; A61L29/00; A61L29/04; A61L29/041; A61L31/00; A61L31/04; A61L31/048; B; B29; B29C; B29C35/00; B29C35/02; B29C35/08; B29C35/0805; B29C2035/085; B29C43/00; B29C43/02; B29C43/16; B29K; B29K2023/00; B29K2023/04; B29K2023/06; B29K2023/0658; B29K2023/0683; B29K2105/00; B29K2105/25; B29K2105/253; B29K2995/00; B29K2995/0037; B29K2995/0087; B29K2995/0089; B29L; B29L2031/00; B29L2031/753; B29L2031/7532; Y; Y10; Y10S; Y10S522/00; Y10S522/915; Y10S525/00; Y10S525/937; Y10S623/00; Y10S623/901
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
103 words
A method for producing raw polymeric matedal having improved oxidation resistance from a plastic resin powder for a medical implant comprising the steps of: placing the resin in a sealed container; removing a substantial portion of the oxygen from said sealed container; repressurizing the sealed container with a gas selected from the group consisting of nitrogen, argon, helium and neon and a combination thereof; then transferring said resin to a forming device which both melts and forms said resin in an oxygen reduced atmosphere to produce the raw material; and thereafter annealing the raw material for a predetermined time at a predetermined temperature.
Claim 2
Independent Claim
103 words
A method for producing raw polymeric matedal having improved oxidation resistance from a plastic resin powder for a medical implant comprising the steps of: placing the resin in a sealed container; removing a substantial portion of the oxygen from said sealed container; repressurizing the sealed container with a gas selected from the group consisting of nitrogen, argon, helium and neon and a combination thereof; then transferring said resin to a forming device which both melts and forms said resin in an oxygen reduced atmosphere to produce the raw material; and thereafter annealing the raw material for a predetermined time at a predetermined temperature.
Claim 3
Dependent Claim
25 words
The method as set forth in claim 1 wherein the oxygen content of the atmosphere in said sealed container is reduced to less than 1%.
Claim 4
Dependent Claim
21 words
The method as set forth in claim 2 wherein said forming device operates in an atmosphere of less than 1% oxygen.
Claim 5
Dependent Claim
23 words
The method as set forth in claim 1 wherein the resin material is polyethylene having a molecular weight of between 400,000 and 10,000,000.
Claim 6
Dependent Claim
48 words
The method for producing a raw material as set forth in claim 1 wherein said removal of said oxygen from said container is a method selected from the group consisting of applying a vacuum, flushing with an inert gas and using an oxygen absorbent and a combination thereof.
Claim 7
Dependent Claim
40 words
The method for producing a raw material as set forth in claim 1 wherein said annealing step takes place at a temperature between about 37° C. and about 135° C. for at least four hours in an oxygen reduced atmosphere.
Claim 8
Independent Claim
89 words
A method for producing raw polymeric material having improved oxidation resistance from a plastic resin powder for a medical implant comprising the steps of: placing the resin in a sealed container; removing a substantial portion of the oxygen from said sealed container; repressurizing the sealed container with a gas selected from the group consisting of nitrogen, argon, helium and neon and a combination thereof; then transferring said resin to a forming device which both melts and forms said resin in an oxygen reduced atmosphere to produce the raw material.
Claim 9
Independent Claim
89 words
A method for producing raw polymeric material having improved oxidation resistance from a plastic resin powder for a medical implant comprising the steps of: placing the resin in a sealed container; removing a substantial portion of the oxygen from said sealed container; repressurizing the sealed container with a gas selected from the group consisting of nitrogen, argon, helium and neon and a combination thereof; then transferring said resin to a forming device which both melts and forms said resin in an oxygen reduced atmosphere to produce the raw material.
Claim 10
Dependent Claim
25 words
The method as set forth in claim 7 wherein the oxygen content of the atmosphere in said sealed container is reduced to less than 1%.
Claim 11
Dependent Claim
21 words
The method as set forth in claim 8 wherein said forming device operates in an atmosphere of less than 1% oxygen.
Claim 12
Dependent Claim
23 words
The method as set forth in claim 7 wherein the resin material is polyethylene having a molecular weight of between 400,000 and 10,000,000.
Claim 13
Dependent Claim
48 words
The method for producing a raw material as set forth in claim 1 wherein said removal of said oxygen from said container is a method selected from the group consisting of applying a vacuum, flushing with an inert gas and using an oxygen absorbent and a combination thereof.
Claim 14
Independent Claim
67 words
A method for producing raw polymeric material having improved oxidation resistance from a plastic resin powder for a medical implant comprising the steps of: placing the resin powder into a forming device which both melts and forms said resin in an oxygen reduced atmosphere to produce the raw polymeric material; and thereafter annealing the raw material for a predetermined time and temperature in an oxygen reduced atmosphere.
Claim 15
Independent Claim
67 words
A method for producing raw polymeric material having improved oxidation resistance from a plastic resin powder for a medical implant comprising the steps of: placing the resin powder into a forming device which both melts and forms said resin in an oxygen reduced atmosphere to produce the raw polymeric material; and thereafter annealing the raw material for a predetermined time and temperature in an oxygen reduced atmosphere.
Claim 16
Dependent Claim
18 words
The method as set forth in claim 12 wherein said oxygen reduced atmospheres have less than 1% oxygen.
Claim 17
Dependent Claim
18 words
The method as set forth in claim 12 wherein said annealing step takes place in an inert atmosphere.
Claim 18
Dependent Claim
32 words
The method as set forth in claim 14 wherein said inert atmosphere is made up of a gas selected from the group consisting of nitrogen, helium, argon, neon and a combination thereof.
Claim 19
Dependent Claim
40 words
The method for producing a raw material as set forth in claim 12 wherein said annealing step takes place at a temperature between about 37° C. and about 135° C. for at least four hours in an oxygen reduced atmosphere.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-09-11 | 1999-03-13 | 1999-09-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-09-11 | 2003-03-13 | 2003-09-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-09-11 | 2007-03-13 | 2007-09-12 | $7700.00 | Window Closed / Lapsed |