EP0700671A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Hydrogel intervertebral disc nucleus
Assignee: Howmedica Osteonics Corp
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Filing: 1995-09-04
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Granted: —
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Expires: 2015-09-04
Abstract
Abstract An article for use in the preparation of a hydrogel prosthetic nucleus, for an intervertebral disc, having equilibrium water contents (EWCs) of from about 30 to about 90 % and compressive strengths of at least 4 meganewtons per square meter (MNm⁻²), at their EWCs, when subjected to the same constraints as the normal nucleus, comprising one or more xerogel rods containing from zero to less than the EWC. A method for preparing a hydrogel prosthetic nucleus, for a vertebral disc, comprising one or more hydrogel rods containing from about 30 to about 90 % water, and having compressive strengths of at least 1 MNm⁻², at their EWCs, which comprises inserting one or more hydrophilic xerogel rods, which at their EWC will contain from about 30 to about 90 % water and have compressive strengths of at least 1 MNm⁻², containing water in an amount from about zero to less than their EWC, into the cavity of the disc through an opening in its annulus and allowing the rod, or rods, to absorb sufficient water from the body fluids to attain their EWCs and essentially fill the intervertebral nuclear disc cavity.
Inventors
- 👤 Qi-Bin Bao
- 👤 Paul A. Higham
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-23 11:06
CPC Classifications
A; A61; A61F; A61F2/00; A61F2/02; A61F2/30; A61F2/44; A61F2/442; A61F2/441; A61F2002/30001; A61F2002/30108; A61F2002/30199; A61F2002/30291; A61F2002/30298; A61F2002/4435; A61F2002/444; A61F2230/00; A61F2230/0063; A61F2230/0091; Y; Y10; Y10S; Y10S623/00; Y10S623/902; Y10S623/908
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
108 words
A prosthetic nucleus implant in the cavity, from which the natural nucleus has been removed, of an intervertebral disc, said cavity being in fluid connection with the outer surroundings of the disc through an opening in its annulus, wherein the prosthetic nucleus comprises at least one hydrophilic xerogel rod wherein all of the rods together are of sufficient length and diameter that the hydrogel, formed therefrom on their absorption of water from an aqueous composition, when hydrated to their equilibrium water content when subjected to the constraints of the annulus and end plates of the disc expands to esentially fill, and conform to the shape of, the cavity.
Claim 2
Dependent Claim
21 words
The prosthetic nucleus of claim 1 wherein the equiibrium water content of the hydrogel is from about 30 to about 90%.
Claim 3
Dependent Claim
21 words
The prosthetic nucleus of claim 2 wherein the equiibrium water content of the hydrogel is from about 60 to about 80%.
Claim 4
Dependent Claim
25 words
The prosthetic nucleus of claim 1 wherein the xerogel has a volume of 10-70% of the volume of the hydrogel at its equilibrium water content.
Claim 5
Dependent Claim
42 words
The prosthetic nucleus of claim 1 wherein the cross-sectional area of an elongated cyclindrical bore in the annulus, connecting the outside thereof with the nuclear cavity of the disc, is approximately equal to or slightly greater than that of the xerogel rod.
Claim 6
Dependent Claim
21 words
The prosthetic nucleus of claim 5 wherein the diameter of the xerogel rod is from about 2 to about 10 mm.
Claim 7
Dependent Claim
21 words
The prosthetic nucleus of claim 6 wherein the diameter of the xerogel rod is from about 4 to about 8 mm.
Claim 8
Dependent Claim
23 words
The prosthetic nucleus of claim 1 wherein the xerogel comprises one or more rods whose total length is sufficient to form said nucleus.
Claim 9
Independent Claim
113 words
A method for preparing a prosthetic nucleus for an intervertebral disc comprising an annulus; a cavity, in fluid connection with the disc's outer surroundings through an opening in the annulus, from which the natural nucleus has been removed, wherein the prosthetic nucleus comprises a hydrogel of sufficient size that it expands to almost completely fill the cavity when its water content reaches its equilibrium value, which comprises inserting at least one hydrophilic xerogel rod, wherein all of the rods together are of sufficient size that the hydrogel, formed on their absorption of water to their EWC will expand to almost completely fill the cavity, into the cavity through the opening in the annulus.
Claim 10
Dependent Claim
20 words
The method of claim 9 wherein the equiibrium water content of the hydrogel is from about 30 to about 90%.
Claim 11
Dependent Claim
17 words
The method of claim 10 wherein the equiibrium water content is from about 70 to about 85%.
Claim 12
Dependent Claim
41 words
The method of claim 9 wherein the cross-sectional area of an elongated cyclindrical bore in the annulus, connecting the outside thereof with the nuclear cavity of the disc, is approximately equal to or slightly greater than that of the xerogel rod.
Claim 13
Dependent Claim
20 words
The method of claim 12 wherein the diameter of the xerogel rod is from about 2 to about 10 mm.
Claim 14
Dependent Claim
20 words
The method of claim 13 wherein the diameter of the xerogel rod is from about 4 to about 8 mm.
Claim 15
Dependent Claim
23 words
The method of claim 9 wherein the xerogel is used in the form of a hydrogel comprising less than its equiibrium water content.
Claim 16
Dependent Claim
27 words
The method of claim 15 wherein the opening in the annulus is of sufficient size to allow the hydrogel rod to pass therethrough and into the cavity.
Claim 17
Dependent Claim
20 words
The method of claim 16 wherein the diameter of the hydrogel rod is from about 2 to about 10 mm.
Claim 18
Dependent Claim
20 words
The method of claim 17 wherein the diameter of the hydrogel rod is from about 4 to about 8 mm.
Claim 19
Dependent Claim
13 words
The prosthetic nucleus of claim 1 wherein the hydrogel comprises a PVA gel.
Claim 20
Dependent Claim
24 words
The prosthetic nucleus of claim 19 wherein the hydrogel is prepared by crystallizing a solution of PVA at a temperature of -10°C or below.
Claim 21
Dependent Claim
60 words
The prosthetic nucleus of claim 1 wherein the hydrogel is prepared from a xerogel prepared by the homo- or co-polymerization of hydrophilic monomers, selected from the group consisting of N-vinyl monomers, hydroxyalkyl acrylates and methacrylates, ethylenically unsaturated acids and bases and their salts and mixtures thereof, in the presence of a cross-linking monomer containing at least two ethylenically unsaturated sites.
Claim 22
Dependent Claim
13 words
The prosthetic nucleus of claim 1 wherein the hydrogel comprises partially hydrolyzed polyacrylonitrile.
Claim 23
Dependent Claim
13 words
The prosthetic nucleus of claim 21 wherein the cross-linking monomer is ethyleneglycol dimethacrylate.
Claim 24
Dependent Claim
39 words
The prosthetic nucleus of claim 21 wherein said hydroxyalkyl methacrylate is 2-hydroxyethyl methacrylate; said N-vinyl monomer is N-vinyl-2-pyrrolidone; said ethylenically unsaturated acid is methacrylic acid; said ethylenically unsaturated base is 2-(diethylamino)ethyl methacrylate; and said cross-linking monomer is ethyleneglycol dimethacrylate.
Claim 25
Dependent Claim
22 words
The prosthetic nucleus of claim 24 wherein said copolymer is formed by copolymerizing said hydrophilic monomer with at least one non-hydrophilic monomer.
Claim 26
Dependent Claim
18 words
The prosthetic nucleus of claim 25 wherein at least one of said non-hydrophilic monomers is an alkyl methacrylate.
Claim 27
Dependent Claim
32 words
The prosthetic nucleus of claim 1 wherein the hydrogel has a compressive strength of at least 1 MNm⁻² when subjected to the constraints of the annulus and end plates of the disc.
Claim 28
Dependent Claim
18 words
The prosthetic nucleus of claim 27 wherein the hydrogel has a compressive strength of at least 4 MNm⁻².
Claim 29
Dependent Claim
34 words
The method of claim 9 wherein the hydrogel at said EWC has a compressive strength of at least 1 MNm⁻² when subjected to the constraints of the annulus and end plates of the disc.
Claim 30
Dependent Claim
18 words
The prosthetic nucleus of claim 29 wherein the hydrogel has a compressive strength of at least 4 MNm⁻².
Claim 31
Dependent Claim
19 words
The prosthetic nucleus of claim 20 wherein the solution comprises a solvent comprising a mixture of DMSO and water.
Claim 32
Dependent Claim
13 words
The prosthetic nucleus of claim 1 wherein said aqueous composition comprises body fluids.
Claim 33
Dependent Claim
16 words
The method of claim 9 wherein said water is absorbed from body fluids in the cavity.
Claim 34
Dependent Claim
14 words
The prosthetic nucleus of claim 25 wherein said non-hydrophilic monomer comprises an alkyl methacrylate.
Claim 35
Dependent Claim
18 words
The method of claim 9 wherein the solution comprises a solvent comprising a mixture of DMSO and water.
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