EP0722973A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Chemically crosslinked ultrahigh molecular weight polyethylene for artificial human joints
Assignee: Orthopaedic Hospital
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Filing: 1996-01-05
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Granted: —
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Expires: 2016-01-05
Abstract
Abstract The present invention discloses a method for enhancing the wear-resistance of polymers by crosslinking them, especially before irradiation sterilization. In particular, this invention presents the use of chemically crosslinked ultrahigh molecular weight polyethylene in in vivo implants.
Inventors
- 👤 Ron Salovey
- 👤 Fu-Wen Shen
- 👤 Harry A. Mckellop
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 22:23
CPC Classifications
A; A61; A61F; A61F2/00; A61F2/02; A61F2/30; A61F2/46; A61F2/468; A61L; A61L27/00; A61L27/14; A61L27/16; B; B29; B29B; B29B13/00; B29B13/08; B29C; B29C71/00; B29C71/0063; C; C08; C08J; C08J5/00; C08J7/00; C08J7/04; C08J7/0427; A61F2/3094; A61F2/32; A61F2/34; A61F2002/30001; A61F2002/30108; A61F2002/30199; A61F2002/30224; A61F2002/30233; A61F2/30767; A61F2/30771; A61F2002/3082; A61F2002/30878; A61F2002/30879; A61F2/36; A61F2/3609; A61F2002/3611; A61F2230/00; A61F2230/0063; A61F2230/0069; 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; B29K2105/24; B29K2995/00; B29K2995/0037; B29K2995/0087; B29K2995/0089; B29L; B29L2031/00; B29L2031/753; B29L2031/7532; C08J2323/00; C08J2323/02; C08J2323/04; C08J2323/06
Claims Analysis
Total Claims: 41
Claim 1
Independent Claim
105 words
A method for producing a crosslinked polymer with increased ability to withstand wear, comprising the steps of: a) crosslinking a polymer to form a crosslinked polymer; b) determining the degree of crystallinity of the crosslinked polymer; and c) adjusting reaction conditions such that the degree of crystallinity of the polymer after crosslinking is reduced by 10% to 50%; wherein the crosslinking is achieved by a method selected from the group consisting of: i) irradiation crosslinking of the polymer when it is in a molten state; ii) photocrosslinking of the polymer in the melt; and iii) crosslinking of the polymer with a free radical generating chemical.
Claim 2
Dependent Claim
18 words
The method of claim 1, further comprising the step of irradiating the crosslinked polymer in the solid state.
Claim 3
Dependent Claim
14 words
The method of claim 2, further comprising the step of annealing the crosslinked polymer.
Claim 4
Independent Claim
71 words
A method for producing a crosslinked polymer with increased ability to withstand wear, comprising the steps of: a) crosslinking a polymer to form a crosslinked polymer without irradiating the polymer in its solid state; b) irradiating the crosslinked polymer in its solid state at a sterilization dose; and c) selecting for the crosslinked polymer which, after the irradiation in step (b), possesses a degree of crystallinity of about 45% or less.
Claim 5
Dependent Claim
52 words
The method of claim 4, wherein the crosslinking is achieved by a method selected from the group consisting of: a) irradiation crosslinking of the polymer when it is in a molten state; b) photocrosslinking of the polymer in the melt; and c) crosslinking of the polymer with a free radical generating chemical.
Claim 6
Dependent Claim
14 words
The method of claim 5, further comprising the step of annealing the crosslinked polymer.
Claim 7
Independent Claim
82 words
A method for producing a crosslinked polymer with increased ability to withstand wear, comprising the steps of: a) crosslinking a polymer to form a crosslinked polymer without irradiating the polymer in its solid state; b) annealing the crosslinked polymer; c) irradiating the crosslinked polymer in its solid state at a sterilization dose; and d) selecting for the crosslinked polymer which, after the irradiation in step (c) and the annealing in step (b), possesses a degree of crystallinity of about 45% or less.
Claim 8
Independent Claim
69 words
A method for making a crosslinked polymer suitable for use in vivo implant, said crosslinked polymer has an increased ability to withstand wear, said method comprising the steps of: a) reducing crystallinity of the polymer by crosslinking the polymer; and b) molding the resulting polymer into a shape suitable for in vivo implant; wherein the crosslinking of step (a) does not include irradiating the polymer in a solid state.
Claim 9
Dependent Claim
51 words
The method of claim 8, wherein the crosslinking is achieved by a method selected from the group consisting of: a) irradiation of the polymer when it is in a molten state; b) photocrosslinking of the polymer in the melt; and c) crosslinking of the polymer with a free radical generating chemical.
Claim 10
Dependent Claim
16 words
The method of claim 9, wherein the crosslinking is achieved with a free radical generating chemical.
Claim 11
Dependent Claim
28 words
The method of claim 10, wherein the free radical generating chemical is selected from the group consisting of: peroxides, peresters, azo compounds, disulfides, dimethacrylates, tetrazenes, and divinyl benzene.
Claim 12
Dependent Claim
17 words
The method of claim 11, further comprising the step of radiation sterilization of the in vivo implant.
Claim 13
Dependent Claim
22 words
The method of claim 12, wherein the degree of crystallinity of the polymer is reduced by between 10 to 50% by crosslinking.
Claim 14
Dependent Claim
18 words
The method of claim 13, further comprising the step of annealing the crosslinked polymer to stabilize its shrinkage.
Claim 15
Dependent Claim
11 words
The method of claim 14, wherein the polymer is UHMW polyhydrocarbon.
Claim 16
Dependent Claim
61 words
An in vivo implant made by a polymer produced by the method comprising the steps of: a) reducing the crystallinity of the polymer to enable it to better withstand wear; and b) molding the polymer into a shape suitable for in vivo implant; wherein the reduction of crystallinity in step (a) does not include irradiating the polymer in a solid state.
Claim 17
Dependent Claim
59 words
The in vivo implant of claim 16, wherein the step (a) is achieved by crosslinking the polymer using a method selected from the group consisting of: a) irradiation crosslinking of the polymer when it is in a molten state; b) photocrosslinking of the polymer in the melt; and c) crosslinking of the polymer with a free radical generating chemical.
Claim 18
Dependent Claim
19 words
The in vivo implant of claim 17, wherein the polymer is chemically crosslinked with a free radical generating chemical.
Claim 19
Dependent Claim
30 words
The in vivo implant of claim 18, wherein the free radical generating chemical is selected from the group consisting of: peroxides, peresters, azo compounds, disulfides, dimethacrylates, tetrazenes, and divinyl benzene.
Claim 20
Dependent Claim
20 words
The in vivo implant of claim 19, wherein the crosslinking reduces the crystallinity of the polymer by 10 to 50%.
Claim 21
Dependent Claim
13 words
The in vivo implant of claim 20, wherein the polymer is a polyhydrocarbon.
Claim 22
Dependent Claim
14 words
The in vivo implant of claim 21, wherein the polyhydrocarbon is an UHMW polyhydrocarbon.
Claim 23
Dependent Claim
36 words
The in vivo implant of claim 17, wherein the in vivo implant is capable of possessing about 45% crystallinity or less if irradiated by gamma irradiation to an average dose of about 3.4 Mrad or less.
Claim 24
Dependent Claim
13 words
The in vivo implant of claim 23, wherein the polymer is UHMW polyhydrocarbon.
Claim 25
Dependent Claim
23 words
The in vivo implant of claim 24, wherein the in vivo implant increases in its degree of crystallinity by about 1% if annealed.
Claim 26
Dependent Claim
30 words
The in vivo implant of claim 23, wherein the free radical generating chemical is selected from the group consisting of: peroxides, peresters, azo compounds, disulfides, dimethacrylates, tetrazenes, and divinyl benzene.
Claim 27
Dependent Claim
25 words
The in vivo implant of claim 26, wherein the polymer is chemically crosslinked by a free radical generating chemical, and the polymer is UHMW polyhydrocarbon.
Claim 28
Dependent Claim
30 words
The in vivo implant of claim 17, capable of suffering less than or equal to one-fifth of the wear suffered by another in vivo implant made from an uncrosslinked polymer.
Claim 29
Dependent Claim
25 words
The in vivo implant of claim 28, wherein the polymer is chemically crosslinked by a free radical generating chemical, and the polymer is UHMW polyhydrocarbon.
Claim 30
Dependent Claim
27 words
A polyhydrocarbon capable of maintaining a degree of crystallinity of about 42% or less after gamma irradiation to an average dose of about 3.4 Mrad or less.
Claim 31
Dependent Claim
20 words
The polyhydrocarbon of claim 30, wherein the polyhydrocarbon has a crystallinity of about 39.8% or less before the gamma irradiation.
Claim 32
Dependent Claim
11 words
The polyhydrocarbon of claim 30, wherein the polyhydrocarbon is UHMW polyhydrocarbon.
Claim 33
Dependent Claim
107 words
A crosslinked in vivo implant comprising a component of an animal joint, said in vivo implant being capable of suffering about one-fifth or less of the wear suffered by an uncrosslinked in vivo implant, wherein the crosslinked in vivo implant and the uncrosslinked in vivo implant are made of UHMW polyethylene and have been sterilized by irradiation, and the crosslink is achieved by a method selected from the group consisting of: a) irradiation crosslinking of the UHMW polyethylene when it is in a molten state; b) photocrosslinking of the UHMW polyethylene in the melt; and c) crosslinking of the UHMW polyethylene with a free radical generating chemical.
Claim 34
Dependent Claim
50 words
The crosslinked in vivo implant of claim 33, wherein the in vivo implant is an acetabular cup and the crosslink is achieved by crosslinking of the UHMW polyethylene with a free radical generating chemical selected from the group consisting of: peroxides, peresters, azo compounds, disulfides, dimethacrylates, tetrazenes, and divinyl benzene.
Claim 35
Dependent Claim
17 words
The crosslinked in vivo implant of claim 34, wherein the free radical generating chemical is a peroxide.
Claim 36
Dependent Claim
16 words
An in vivo implant made from a polyhydrocarbon having a crystallinity of about 43% or less.
Claim 37
Dependent Claim
25 words
The in vivo implant of claim 36, capable of maintaining a crystallinity of 45% or less after irradiation with gamma irradiation at a sterilization dose.
Claim 38
Dependent Claim
13 words
The in vivo implant of claim 37, wherein said polyhydrocarbon is UHMW polyethylene.
Claim 39
Dependent Claim
14 words
The in vivo implant of claim 38, wherein the UHMW polyethylene is chemically crosslinked.
Claim 40
Dependent Claim
40 words
The in vivo implant of claim 39, wherein the UHMW polyethylene has a crystallinity of about 40% before irradiation in the solid state, and a crystallinity of about 42% after gamma irradiation to an average dose of about 3.4 Mrad.
Claim 41
Dependent Claim
13 words
The in vivo implant of claim 36, wherein the polyhydrocarbon is chemically crosslinked.
References Cited (Backward Citations)
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