US5543471A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Non-oxidizing polymeric medical implant
Assignee: Howmedica Osteonics Corp
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Filing: 1995-03-15
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Granted: 1996-08-06
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Expires: 2015-03-15
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 06:33
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: 11
Claim 1
Independent Claim
76 words
A medical implant made of an olefinic material having a molecular weight of 400,000 to 10,000,000 comprising polymeric chains having a free radical concentration of less than 1×10 17 /g achieved by irradiating said material and thereafter by heating said material to a temperature of between about 25° C. and about 140° C. for at least about four hours in an atmosphere having no more than 1% oxygen prior to the oxidation of said free radicals.
Claim 2
Dependent Claim
76 words
A medical implant made of an olefinic material having a molecular weight of 400,000 to 10,000,000 comprising polymeric chains having a free radical concentration of less than 1×10 17 /g achieved by irradiating said material and thereafter by heating said material to a temperature of between about 25° C. and about 140° C. for at least about four hours in an atmosphere having no more than 1% oxygen prior to the oxidation of said free radicals.
Claim 3
Dependent Claim
24 words
The medical implant as set forth in claim 1 wherein said polymeric material is polyethylene having a molecular weight of between 400,000 and 10,000,000.
Claim 4
Dependent Claim
60 words
A medical implant comprising an olefinic material said material irradiated while in an atmosphere with no more than 1% oxygen therein, and thereafter being annealed in an atmosphere having no more than 1% oxygen at a temperature of between 25° C. and the melting point of said olefinic material and for a sufficient time to inactivate any residual free radicals.
Claim 5
Dependent Claim
60 words
A medical implant comprising an olefinic material said material irradiated while in an atmosphere with no more than 1% oxygen therein, and thereafter being annealed in an atmosphere having no more than 1% oxygen at a temperature of between 25° C. and the melting point of said olefinic material and for a sufficient time to inactivate any residual free radicals.
Claim 6
Dependent Claim
19 words
The medical implant of claim 3 wherein said free radicals include peroxy and hydroperoxy groups on the polymer chains.
Claim 7
Dependent Claim
15 words
The medical implant of claim 3 wherein said atmosphere comprises inert gas or a vacuum.
Claim 8
Dependent Claim
71 words
A medical implant comprising an olefinic polymeric material having a molecular weight of 400,000 to 10,000,000 said material irradiated while in an atmosphere having no more than 1% oxygen and thereafter heated in an atmosphere having no more than 1% oxygen for a sufficient time and at a temperature of between 25° C. and the melting point of said olefinic material to form cross-links between free radicals in neighboring polymeric chains.
Claim 9
Dependent Claim
71 words
A medical implant comprising an olefinic polymeric material having a molecular weight of 400,000 to 10,000,000 said material irradiated while in an atmosphere having no more than 1% oxygen and thereafter heated in an atmosphere having no more than 1% oxygen for a sufficient time and at a temperature of between 25° C. and the melting point of said olefinic material to form cross-links between free radicals in neighboring polymeric chains.
Claim 10
Dependent Claim
19 words
The medical implant of claim 6 wherein said free radicals include peroxy and hydroperoxy groups on the polymer chains.
Claim 11
Dependent Claim
15 words
The medical implant of claim 6 wherein said atmosphere comprises inert gas or a vacuum.
References Cited (Backward Citations)
US4965846A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-08-06 | 2000-02-05 | 2000-08-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-08-06 | 2004-02-05 | 2004-08-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-08-06 | 2008-02-05 | 2008-08-06 | $7700.00 | Window Closed / Lapsed |