Patent US5414049A successfully refreshed from Google Patents.
US5414049A
Expired / Lapsed
US
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Non-oxidizing polymeric medical implant
Assignee: Howmedica Osteonics Corp
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Filing: 1993-06-01
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Granted: 1995-05-09
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Expires: 2013-06-01
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 airtight 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
2026-11-05 21:52
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: 47
Claim 1
Independent Claim
76 words
A method for producing a medical implant formed from an olefinic material, the material having improved oxidation resistance comprising the steps of: sealing the implant in an oxygen impermeable package in an oxygen reduced non-reactive atmosphere; radiation sterilizing said packaged implant; and heating said packaged implant for a predetermined time at a temperature of between about 37° C. and the melting point of said olefinic material to form cross-links between free radicals in neighboring polymeric chains.
Claim 2
Independent Claim
76 words
A method for producing a medical implant formed from an olefinic material, the material having improved oxidation resistance comprising the steps of: sealing the implant in an oxygen impermeable package in an oxygen reduced non-reactive atmosphere; radiation sterilizing said packaged implant; and heating said packaged implant for a predetermined time at a temperature of between about 37° C. and the melting point of said olefinic material to form cross-links between free radicals in neighboring polymeric chains.
Claim 3
Dependent Claim
24 words
The method for producing an implant set forth in claim 1 wherein said predetermined temperature is between about 37° C. and about 70° C.
Claim 4
Dependent Claim
22 words
The method for producing an implant as set forth in claim 2 wherein said predetermined time is at least forty eight hours.
Claim 5
Dependent Claim
26 words
The method for producing an implant as set forth in claim 3 wherein said predetermined temperature is 50° C. and said predetermined time is 144 hours.
Claim 6
Dependent Claim
30 words
The method for producing an implant as set forth in claim 1 wherein the polymeric material is ultra high molecular weight polyethylene having a molecular weight between 400,000 and 10,000,000.
Claim 7
Dependent Claim
26 words
The method for producing an implant as set forth in claim 5 wherein said predetermined temperature is 50° C. and said predetermined time is 144 hours.
Claim 8
Dependent Claim
25 words
The method for producing an implant as set forth in claim 1 wherein said radiation sterilization is performed by gamma, x-ray or electron beam radiation.
Claim 9
Dependent Claim
19 words
The method as set forth in claim 1 wherein said oxygen reduced atmosphere has no more than 1% oxygen.
Claim 10
Dependent Claim
38 words
The method for producing an implant as set forth in claim 8 wherein said oxygen reduced atmosphere is made up of a gas selected from the group consisting of nitrogen, helium, argon, and neon and a combination thereof.
Claim 11
Dependent Claim
29 words
The method for producing an implant as set forth in claim 8 wherein said reduced oxygen atmosphere is produced by a vacuum of less than 3 inches of mercury.
Claim 12
Dependent Claim
76 words
The method for producing an implant as set forth in claim 8 wherein said sealing in a reduced oxygen atmosphere is produced by first flushing said package with a gas selected from the group consisting of nitrogen, helium, argon and neon and a combination thereof, followed by applying a vacuum of less than 3 inches of mercury to said package, followed by flushing said package with a gas selected from said group and a combination thereof.
Claim 13
Independent Claim
76 words
A method for producing a medical implant made from an olefinic material having a molecular weight of between 400,000 and 10,000,000 comprising the steps of: forming the implant from the olefinic material; packaging the formed implant in an inert atmosphere; radiation sterilizing said packaged implant while maintaining said inert atmosphere; and heating said packaged implant while maintaining said inert atmosphere for at least 48 hours at a temperature of about 37° C. to about 70° C.
Claim 14
Independent Claim
76 words
A method for producing a medical implant made from an olefinic material having a molecular weight of between 400,000 and 10,000,000 comprising the steps of: forming the implant from the olefinic material; packaging the formed implant in an inert atmosphere; radiation sterilizing said packaged implant while maintaining said inert atmosphere; and heating said packaged implant while maintaining said inert atmosphere for at least 48 hours at a temperature of about 37° C. to about 70° C.
Claim 15
Dependent Claim
22 words
The method for producing an implant as set forth in claim 12 wherein the olefinic material is ultra high molecular weight polyethylene.
Claim 16
Dependent Claim
26 words
The method for producing an implant as set forth in claim 12 wherein said predetermined temperature is 50° C. and said predetermined time is 144 hours.
Claim 17
Dependent Claim
19 words
The method as set forth in claim 12 wherein said oxygen reduced atmosphere has no more than 1% oxygen.
Claim 18
Dependent Claim
37 words
The method for producing an implant as set forth in claim 15 wherein said inert atmosphere is made up of a gas selected from the group consisting of nitrogen, helium, argon, and neon and a combination thereof.
Claim 19
Dependent Claim
28 words
The method for producing an implant as set forth in claim 15 wherein said inert atmosphere is produced by a vacuum of less than 3 inches of mercury.
Claim 20
Dependent Claim
18 words
The method as set forth in claim 12 wherein said heating step is performed in an inert atmosphere.
Claim 21
Independent Claim
78 words
A method for producing a medical implant from an olefinic material having a molecular weight greater than 400,000 comprising the steps of: sealing the implant in an oxygen impermeable package in an oxygen reduced atmosphere having an absence of agents which can react with free radicals in the polymeric chain; radiation sterilizing said packaged implant; and heating said sealed packaged implant for a predetermined time and temperature sufficient to form cross-links between free radicals in neighboring polymeric chains.
Claim 22
Independent Claim
78 words
A method for producing a medical implant from an olefinic material having a molecular weight greater than 400,000 comprising the steps of: sealing the implant in an oxygen impermeable package in an oxygen reduced atmosphere having an absence of agents which can react with free radicals in the polymeric chain; radiation sterilizing said packaged implant; and heating said sealed packaged implant for a predetermined time and temperature sufficient to form cross-links between free radicals in neighboring polymeric chains.
Claim 23
Dependent Claim
19 words
The method as set forth in claim 19 wherein said oxygen reduced atmosphere has no more than 1% oxygen.
Claim 24
Dependent Claim
38 words
The method for producing an implant as set forth in claim 20 wherein said oxygen reduced atmosphere is made up of a gas selected from the group consisting of nitrogen, helium, argon, and neon and a combination thereof.
Claim 25
Dependent Claim
29 words
The method for producing an implant as set forth in claim 20 wherein said oxygen reduced atmosphere is produced by a vacuum of less than 3 inches of mercury.
Claim 26
Dependent Claim
76 words
The method for producing an implant as set forth in claim 20 wherein said sealing in said oxygen reduced atmosphere is produced by first flushing said package with a gas selected from the group consisting of nitrogen, helium, argon and neon and a combination thereof, followed by applying a vacuum of less than 3 inches of mercury to said package, followed by flushing said package with a gas selected from said group and a combination thereof.
Claim 27
Dependent Claim
30 words
The method for producing an implant as set forth in claim 19 wherein the olefinic material is ultra high molecular weight polyethylene having a molecular weight between 400,000 and 10,000,000.
Claim 28
Independent Claim
74 words
A method for producing a medical implant made from olefinic material having a molecular weight greater than 400,000 comprising the steps of: sealing the implant in an oxygen impermeable package in an inert atmosphere; radiation sterilizing said packaged implant; and heating said packaged implant for at least four hours at a temperature of between 37° C. and the melting point of said olefinic material to form cross-links between free radicals in neighboring polymeric chains.
Claim 29
Independent Claim
74 words
A method for producing a medical implant made from olefinic material having a molecular weight greater than 400,000 comprising the steps of: sealing the implant in an oxygen impermeable package in an inert atmosphere; radiation sterilizing said packaged implant; and heating said packaged implant for at least four hours at a temperature of between 37° C. and the melting point of said olefinic material to form cross-links between free radicals in neighboring polymeric chains.
Claim 30
Dependent Claim
18 words
The method as set forth in claim 25 wherein said inert atmosphere has no more than 1% oxygen.
Claim 31
Dependent Claim
37 words
The method for producing an implant as set forth in claim 26 wherein said inert atmosphere is made up of a gas selected from the group consisting of nitrogen, helium, argon, and neon and a combination thereof.
Claim 32
Dependent Claim
28 words
The method for producing an implant as set forth in claim 26 wherein said inert atmosphere is produced by a vacuum of less than 3 inches of mercury.
Claim 33
Dependent Claim
76 words
The method for producing an implant as set forth in claim 26 wherein said sealing in said inert reactive atmosphere is produced by first flushing said package with a gas selected from the group consisting of nitrogen, helium, argon and neon and a combination thereof, followed by applying a vacuum of less than 3 inches of mercury to said package, followed by flushing said package with a gas selected from said group and a combination thereof.
Claim 34
Dependent Claim
30 words
The method for producing an implant as set forth in claim 25 wherein the olefin material is ultra high molecular weight polyethylene having a molecular weight between 400,000 and 10,000,000.
Claim 35
Independent Claim
73 words
A method for producing a medical implant formed from an olefinic material comprising the steps of: forming the implant from an olefinic material having a molecular weight of 400,000 to 10,000,000; sealing the formed implant in an oxygen impermeable package in a substantially oxygen-free atmosphere; radiation sterilizing said packaged implant; and heating said sealed package implant for a predetermined time and temperature sufficient to form cross-links between free radicals in neighboring polymeric chains.
Claim 36
Independent Claim
73 words
A method for producing a medical implant formed from an olefinic material comprising the steps of: forming the implant from an olefinic material having a molecular weight of 400,000 to 10,000,000; sealing the formed implant in an oxygen impermeable package in a substantially oxygen-free atmosphere; radiation sterilizing said packaged implant; and heating said sealed package implant for a predetermined time and temperature sufficient to form cross-links between free radicals in neighboring polymeric chains.
Claim 37
Dependent Claim
20 words
The method for producing an implant as set forth in claim 31 wherein said atmosphere contains less than 1% oxygen.
Claim 38
Dependent Claim
39 words
The method for producing an implant as set forth in claim 32 wherein said substantially oxygen free atmosphere is made up of a gas selected from the group consisting of nitrogen, helium, argon, and neon and a combination thereof.
Claim 39
Dependent Claim
30 words
The method for producing an implant as set forth in claim 32 wherein said substantially oxygen free atmosphere is produced by placing deoxidizing agents in said package prior to sealing.
Claim 40
Dependent Claim
22 words
The method for producing an implant as set forth in claim 32 wherein the polymeric material is ultra high molecular weight polyethylene.
Claim 41
Independent Claim
65 words
A method for producing a sterile polymeric medical implant having improved oxidation resistance comprising the steps of: sealing a polymeric medical implant in an oxygen-free atmosphere contained in a container comprising an oxygen impermeable composition; sterilizing said implant by irradiation; and heating said package and implant at a sufficient temperature and for a sufficient time to inactivate any residual free radicals and/or free radical precursors.
Claim 42
Independent Claim
65 words
A method for producing a sterile polymeric medical implant having improved oxidation resistance comprising the steps of: sealing a polymeric medical implant in an oxygen-free atmosphere contained in a container comprising an oxygen impermeable composition; sterilizing said implant by irradiation; and heating said package and implant at a sufficient temperature and for a sufficient time to inactivate any residual free radicals and/or free radical precursors.
Claim 43
Dependent Claim
22 words
The method of claim 36 wherein said implant is formed from a polymeric article which has been freed of occluded oxygen gas.
Claim 44
Dependent Claim
19 words
The method of claim 36 wherein said free radical precursors include peroxy and hydroperoxy groups on the polymer chains.
Claim 45
Dependent Claim
17 words
The method of claim 36 wherein said oxygen free atmosphere comprises an inert gas or a vacuum.
Claim 46
Dependent Claim
15 words
The method of claim 39 wherein said inert gas contains no more than 1% oxygen.
Claim 47
Dependent Claim
19 words
The method of claim 39 wherein said atmosphere comprises a vacuum of not more than 3 inches of Mercury.
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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) | 1998-05-08 | 1998-11-07 | 1999-05-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-05-08 | 2002-11-07 | 2003-05-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-05-08 | 2006-11-07 | 2007-05-09 | $7700.00 | Window Closed / Lapsed |