Patent US6165220A successfully refreshed from Google Patents.
US6165220A
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Wear resistant surface-gradient crosslinked polyethylene
Assignee: ORTHOPEADIC HOSPITAL
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Filing: 1998-04-14
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Granted: 2000-12-26
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Expires: 2018-04-14
Abstract
Abstract A method for improving the wear resistance of an implant by crosslinking its bearing surface layer, while leaving its non-bearing interior uncrosslinked. Such crosslinking may be achieved by electron-beam irradiation or by chemical crosslinking of the implant. The resulting implant may be further treated to remove the residual free radicals (generated by the electron beam crosslinking process), to remove its most oxidized layer, and/or to stabilize its size. In the case of chemical crosslinking, the resulting implant may be further treated to remove residual chemicals from the crosslinked surface layer.
Inventors
- 👤 Harry Alden McKellop
- 👤 Fu-Wen Shen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 10:18
CPC Classifications
C; C08; C08J; C08J3/00; C08J3/24; C08J3/245; A; A61; A61F; A61F2/00; A61F2/02; A61F2/30; A61F2/30767; A61F2/32; A61F2/34; A61L; A61L27/00; A61L27/14; A61L27/16; A61L27/28; A61L27/50; B; B29; B29B; B29B13/00; B29B13/08; B29C; B29C71/00; B29C71/04; A61F2/3094; A61F2002/30001; A61F2002/30667; A61F2002/30682; A61F2002/30685; A61F2002/30934; A61F2/30942; A61F2002/30957; A61F2250/00; A61F2250/0014; A61F2250/0057; B29C35/00; B29C35/02; B29C35/08; B29C35/0866; B29C2035/0877; B29C71/0009; B29C2071/0027; B29C71/02; B29C2071/022; B29C2791/00; B29C2791/001; B29C35/0266; B29K; B29K2023/00; B29K2023/04; B29K2023/06; B29K2023/0658; B29K2023/0675; B29K2023/0683; B29K2995/00; B29K2995/0037; B29K2995/0087; B29L; B29L2031/00; B29L2031/753; B29L2031/7532; C08J2323/00; C08J2323/02; C08J2323/04; C08J2323/06; C08L; C08L23/00; C08L23/02; C08L23/04; C08L23/06; Y; Y10; Y10S; Y10S623/00; Y10S623/901
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
73 words
A surface-gradient crosslinked implant comprising a polyethylene bearing surface having a maximum gel content of from about 80 to about 100% within the bearing surface, the gel content gradually decreasing to about 50% of the bearing surface gel content at about 0.5 to about 2 mm from the bearing surface, and tapering to nearly zero by about 2 to about 3 mm from the bearing surface; the remainder of the implant remains uncrosslinked.
Claim 2
Dependent Claim
73 words
A surface-gradient crosslinked implant comprising a polyethylene bearing surface having a maximum gel content of from about 80 to about 100% within the bearing surface, the gel content gradually decreasing to about 50% of the bearing surface gel content at about 0.5 to about 2 mm from the bearing surface, and tapering to nearly zero by about 2 to about 3 mm from the bearing surface; the remainder of the implant remains uncrosslinked.
Claim 3
Independent Claim
70 words
A method for improving the wear resistance of a bearing surface of an implant, wherein said bearing surface comprises polyethylene, the method comprises the step of subjecting the bearing surface of the implant which is fully formed to electron-beam radiation to crosslink the bearing surface, while the remainder of the implant that is not part of the bearing surface is not subjected to the electron-beam radiation and, therefore, remains uncrosslinked.
Claim 4
Independent Claim
70 words
A method for improving the wear resistance of a bearing surface of an implant, wherein said bearing surface comprises polyethylene, the method comprises the step of subjecting the bearing surface of the implant which is fully formed to electron-beam radiation to crosslink the bearing surface, while the remainder of the implant that is not part of the bearing surface is not subjected to the electron-beam radiation and, therefore, remains uncrosslinked.
Claim 5
Dependent Claim
81 words
The method of claim 2, wherein the irradiated implant is further subjected to one or more of the following steps: (1) pressurization in hydrogen to reduce residual free radicals generated by the irradiation, (2) annealing or remelting the implant to reduce residual free radicals generated by the irradiation, (3) shaping the implant into a final shape, and (4) treating with ethylene oxide the irradiated implant, either in its original or final shape, to reduce residual free radicals generated by the irradiation.
Claim 6
Dependent Claim
24 words
The method of claim 3, wherein the shaping step comprises removing the most oxidized outer layer of the bearing surface of the irradiated implant.
Claim 7
Independent Claim
69 words
A method for improving wear resistance of a bearing surface of an implant, wherein said bearing surface comprises polyethylene, the method comprising the step of crosslinking the polyethylene with a free radical generating chemical, during a process for making the implant so that the remainder of the implant, when made, that is not part of the bearing surface remains uncrosslinked, the resultant implant is termed a surface crosslinked implant.
Claim 8
Independent Claim
69 words
A method for improving wear resistance of a bearing surface of an implant, wherein said bearing surface comprises polyethylene, the method comprising the step of crosslinking the polyethylene with a free radical generating chemical, during a process for making the implant so that the remainder of the implant, when made, that is not part of the bearing surface remains uncrosslinked, the resultant implant is termed a surface crosslinked implant.
Claim 9
Dependent Claim
53 words
The method of claim 5, further comprising one or more of the following steps of: (1) reducing residual chemicals resulting from the crosslinking process, (2) annealing the surface crosslinked implant at a temperature and for a time sufficient to stabilize its size, and (3) shaping the surface crosslinked implant into its final shape.
Claim 10
Dependent Claim
14 words
The method of claim 6, wherein the free radical generating agent is a peroxide.
Claim 11
Dependent Claim
27 words
The method of claim 6, wherein step (1) comprises soaking the surface crosslinked implant in a solvent to reduce the residual chemicals resulting from the crosslinking process.
Claim 12
Dependent Claim
21 words
The method of claim 6, wherein the shaping step comprises removing the outer most oxidized layer from the surface crosslinked implant.
Claim 13
Independent Claim
72 words
A method for improving the wear resistance of a bearing surface of an implant, wherein said bearing surface comprises polyethylene, the method comprises the step of subjecting the bearing surface of the implant which is partially formed to electron-beam radiation to crosslink the bearing surface, while the remainder of the partially formed implant that is not part of the bearing surface is not subjected to the electron-beam radiation and, therefore, remains uncrosslinked.
Claim 14
Independent Claim
72 words
A method for improving the wear resistance of a bearing surface of an implant, wherein said bearing surface comprises polyethylene, the method comprises the step of subjecting the bearing surface of the implant which is partially formed to electron-beam radiation to crosslink the bearing surface, while the remainder of the partially formed implant that is not part of the bearing surface is not subjected to the electron-beam radiation and, therefore, remains uncrosslinked.
Claim 15
Dependent Claim
85 words
The method of claim 10, wherein the irradiated partially formed implant is further subjected to one or more of the following steps: (1) pressurization in hydrogen to reduce residual free radicals generated by the irradiation, (2) annealing or remelting to reduce residual free radicals generated by the irradiation, (3) shaping the partially formed implant into a final shape, and (4) treating with ethylene oxide the irradiated partially formed implant, either in its original or final shape, to reduce residual free radicals generated by the irradiation.
Claim 16
Dependent Claim
26 words
The method of claim 11, wherein the shaping step comprises removing the most oxidized outer layer of the bearing surface of the irradiated partially formed implant.
Claim 17
Dependent Claim
15 words
An implant produced by any one of the foregoing methods of claims 2 to 12.
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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) | 2003-12-26 | 2004-06-26 | 2004-12-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-12-26 | 2008-06-26 | 2008-12-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-12-26 | 2012-06-26 | 2012-12-26 | $7700.00 | Window Closed / Lapsed |