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Medical implant or medical implant part and method for producing the same

a technology for medical implants and parts, applied in the direction of prosthesis, woodworking apparatus, synthetic resin layered products, etc., can solve the problems of orthopaedic implants that cannot be replaced, pain and/or loosening of orthopaedic implants, and need to be revised and/or replaced,

Inactive Publication Date: 2006-06-01
DEPUY PROD INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In recent years, it has become increasingly apparent that tissue necrosis and osteolysis at the interface of the orthopaedic implant and the host bone are primary contributors to the long-term loosening failure of prosthetic joints.
Eventually, the orthopaedic implant becomes painful and / or loose and must be revised and / or replaced.
However, the free radicals formed upon irradiation of UHMWPE can also participate in oxidation reactions which reduce the molecular weight of the polymer via chain scission, leading to degradation of physical properties, embrittlement, and a significant increase in wear rate.
Moreover, the three-dimensional network produced by the cross-linking reaction can reduce the mechanical properties of the UHMWPE.
Moreover, while the cross-linking of the UHMWPE and other known methods can increase the wear resistance of a medical implant or medial implant part comprising UHMWPE, such implants or implant parts can still produce microscopic wear particles of UHMWPE that can lead to the eventual failure of the medical implant or medical implant part.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0033] This example demonstrates the properties of a medical implant or medical implant part of the invention. This example further demonstrates the production of a medical implant or medical implant part according to the method of the invention. Approximately 2 g of powdered poly(ethylene oxide) (WSR-303 available from Dow, Midland, Mich.), which has a weight average molecular weight of approximately 7.0 million atomic mass units and a melt index of less than about 0.5 g / 10 min, was dry blended with approximately 23 g of powdered ultrahigh molecular weight polyethylene (GUR 1020 available from Ticona, Summit, N.J.). The mixture comprised approximately 8 wt. % of poly(ethylene oxide), which is equivalent to approximately 6.4% by volume. The mixture of poly(ethylene oxide) and ultrahigh molecular weight polyethylene was then placed in a compression mold and compressed under a suitable temperature and pressure until the ultrahigh molecular weight polyethylene consolidated to produce a...

example 2

[0036] This example demonstrates the properties of a medical implant or medical implant part of the invention. This example also demonstrates the production of a medical implant or medical implant part according to the method of the invention. Approximately 2 g of powdered poly(ethylene oxide) (WSR-303 available from Dow, Midland, Mich.), which has a weight average molecular weight of approximately 7.0 million atomic mass units and a melt index of less than 0.5 g / 10 min, was dry blended with approximately 23 g of powdered ultrahigh molecular weight polyethylene (GUR 1020 available from Ticona, Summit, N.J.). The mixture comprised approximately 8 wt. % of poly(ethylene oxide), which is equivalent to approximately 6.4% by volume. The mixture of poly(ethylene oxide) and ultrahigh molecular weight polyethylene was then placed in a compression mold and compressed under a suitable temperature and pressure until the ultrahigh molecular weight polyethylene consolidated to produce a composit...

example 3

[0040] This example demonstrates the optional cross-linking of the hydrophilic polymer and ultrahigh molecular weight polyethylene in a medical implant or medical implant part according to the invention. Three composites (Composite 3A, 3B, and 3C) comprising a mixture of a hydrophilic polymer (i.e., poly(ethylene oxide)) and ultrahigh molecular weight polyethylene were prepared in accordance with the procedures set forth in Example 1 (Composite 3A) and Example 2 (Composite 3C). Composite 3B was generally prepared in accordance with the procedure set forth in Example 2, but the composite was not subjected to the quench process following gamma irradiation. Each composite was then submerged in a sonicated water bath for approximately 24 hours at a temperature of approximately 65° C. The composites then were removed from the water bath, dried, and weighed to determine the change in weight due to submersion in the water bath. The results of the measurements are summarized below in Table ...

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Abstract

The invention provides a medical implant or medical implant part comprising a body and a surface layer, wherein the surface layer comprises a mixture comprising at least one hydrophilic polymer and ultrahigh molecular weight polyethylene having a weight average molecular weight of about 400,000 atomic mass units or more. The invention also provides a method for producing such a medical implant or medical implant.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] This is a divisional of co-pending U.S. patent application Ser. No. 10 / 675,047, filed Sep. 30, 2003, the disclosure of which is incorporated by reference in its entirety.FIELD OF THE INVENTION [0002] This invention pertains to medical implants or medical implant parts comprised of ultrahigh molecular weight polyethylene and methods of producing and using the same. BACKGROUND OF THE INVENTION [0003] Ultrahigh molecular weight polyethylene (“UHMWPE”) is commonly used in making orthopaedic implants, such as artificial hip joints. In recent years, it has become increasingly apparent that tissue necrosis and osteolysis at the interface of the orthopaedic implant and the host bone are primary contributors to the long-term loosening failure of prosthetic joints. It is generally accepted by orthopaedic surgeons and biomaterials scientists that this tissue necrosis and osteolysis is due, at least in part, to the presence of microscopic particles ...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B32B27/32A61L27/34A61L27/48A61L31/12
CPCA61L27/34B29C43/003B29K2023/0683B29K2995/0087B29L2031/7532C08L23/06Y10T428/269C08L2312/06C08L71/02C08L2666/22Y10T428/31855Y10T428/31913Y10T428/31928Y10T428/31935Y10T428/31938
Inventor KING, RICHARD S.HANES, MARK D.
Owner DEPUY PROD INC
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