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Biomaterials. 2010 May;31(13):3643-8. doi: 10.1016/j.biomaterials.2010.01.076. Epub 2010 Feb 9.

Use of vitamin E to protect cross-linked UHMWPE from oxidation.

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  • 1Mathys Ltd. Bettlach, G├╝terstrasse 5, CH-2544 Bettlach, Switzerland. reto.lerf@mathysmedical.com

Abstract

Wear and oxidative degradation may limit the life span of UHMWPE implants. Cross-linking and stabilisation by vitamin E are proposed to overcome wear and degradation. The present investigation takes a close look to the oxidative behaviour of cross-linked and stabilised UHMWPE. First, the consolidated vitamin E stabilised UHMWPE was qualified in terms of microstructure and homogeneity of the distribution of the additive to be suitable for oxidation profiles over the entire section. Then cross-linked samples with five different concentrations of vitamin E (nil to 1.0%) underwent two different ageing protocols. The first was under pressurized oxygen at 70 degrees C, as defined in the ASTM F 2003 standard with a prolonged period of 60 days, the second was in 5% aqueous hydrogen peroxide solution with iron (III) chloride as catalyst at 50 degrees C. The first accelerated ageing protocol showed that a vitamin E concentration as low as 0.05% is effective to protect irradiated highly cross-linked UHMWPE against oxidation when exposed direct to oxygen. Vitamin E stabilised, highly cross-linked UHMWPE exhibits therefore no oxidation potential origination from the irradiation treatment. Analysis of samples treated by the second chemical ageing yielded, that vitamin E is effective to prolong initial stability against a supplementary attack of hydrogen peroxide and reactive radicals. The time period of stability against the aggressive hydrogen peroxide solution increases with increasing vitamin E content. However, even 0.05% have a marked stabilisation effect. Therefore, such small additions of vitamin E are effective to protect the UHMWPE material against a supplementary exposure to in vivo oxidation after the irradiation treatment. In conclusion, vitamin E shields cross-linked UHMWPE for orthopaedic application against oxidation in the heat of consolidation, during irradiation treatment and finally while implanted in the human body.

Copyright 2010 Elsevier Ltd. All rights reserved.

PMID:
20144479
[PubMed - indexed for MEDLINE]
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