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α-Tocopherol-doped irradiated UHMWPE for high fatigue resistance and low wear

Paper ID Volume ID Publish Year Pages File Format Full-Text
12708 813 2004 8 PDF Available
Title
α-Tocopherol-doped irradiated UHMWPE for high fatigue resistance and low wear
Abstract

Longevity of total joints has been compromised by wear and fatigue of ultrahigh molecular weight polyethylene (UHMWPE) components. Crosslinking reduces UHMWPE wear, but combined with postirradiation melting, also reduces its fatigue strength, therefore limiting its use in high-stress applications. We hypothesized that a lipophilic antioxidant (α-tocopherol, α-T) can protect UHMWPE against oxidation eliminating the need for postirradiation melting of crosslinked UHMWPE and improve its fatigue strength. To test these hypotheses, 65- and 100-kGy irradiated, α-T-doped and subsequently γ-sterilized UHMWPE were used. (I) α-T-doped irradiated UHMWPEs showed significantly lower oxidation levels (0.48±0.25 and 0.44±0.06) compared to 100-kGy irradiated UHMWPE (3.74±0.16) after 5 weeks of accelerated aging at 80°C in air. (II) Wear rate of α-T-doped irradiated UHMWPE (1.9±0.5, and 0.9±0.1 mg/million cycles (MC) for 65- and 100-kGy irradiated UHMWPE, respectively) were comparable to that of 100-kGy irradiated/melted UHMWPE (1.1±0.7 mg/million cycles). (III) The stress intensity factor at crack inception (ΔKi) of 100-kGy irradiated UHMWPE increased significantly upon doping with α-T from 0.74 to 0.87 MPa m1/2 (p<0.01). The ΔKi for the 100-kGy irradiated and melted UHMWPE, currently in clinical use, was 0.55 MPa m1/2. Doping with α-T eliminated the need for postirradiation melting to protect irradiated UHMWPE against long-term oxidation. The fatigue strength was improved by 58% for α-T-doped 100-kGy irradiated UHMWPE compared to irradiated and melted UHMWPE. The increase in oxidative stability of α-T-doped UHMWPE is attributed to the ability of α-T to react with peroxy free radicals on lipid chains and arrest the oxidation reactions. The improved fatigue strength is attributed to the increase in plasticity of UHMWPE due to the lipophilic nature of α-T.

Keywords
UHMWPE; Arthroplasty; Fatigue; Antioxidant; Lipid
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α-Tocopherol-doped irradiated UHMWPE for high fatigue resistance and low wear
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Publisher
Database: Elsevier - ScienceDirect
Journal: Biomaterials - Volume 25, Issue 24, November 2004, Pages 5515–5522
Authors
, , , , ,
Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us