The effect of α-tocopherol on the oxidation and free radical decay in irradiated UHMWPE

Oral, Ebru; Rowell, Shannon L.; Muratoglu, Orhun K.

doi:10.1016/j.biomaterials.2006.07.017

Cited by 132 publications

(101 citation statements)

References 42 publications

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“…Under accelerated aging at elevated temperatures and/or in the presence of pure oxygen, vitamin E-stabilized, irradiated UHMWPE was oxidatively more stable than gamma-sterilized or high-dose irradiated UHMWPE [11,55,60,62,84]. Thus, in vitro studies corroborated the hypothesis that vitamin E would increase the oxidative stability of irradiated UHMWPEs.…”

Section: The Rationale For Using the Antioxidant Vitamin Ementioning

confidence: 67%

Vitamin E-stabilized UHMWPE for Total Joint Implants: A Review

Bracco

Oral

2011

Clinical Orthopaedics &Amp; Related Research

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Background Osteolysis due to wear of UHMWPE limits the longevity of joint arthroplasty. Oxidative degradation of UHMWPE gamma-sterilized in air increases its wear while decreasing mechanical strength. Vitamin E stabilization of UHMWPE was proposed to improve oxidation resistance while maintaining wear resistance and fatigue strength. Questions/purposes We reviewed the preclinical research on the development and testing of vitamin E-stabilized UHMWPE with the following questions in mind: (1) What is the rationale behind protecting irradiated UHMWPE against oxidation by vitamin E? (2) What are the effects of vitamin E on the microstructure, tribologic, and mechanical properties of irradiated UHMWPE? (3) Is vitamin E expected to affect the periprosthetic tissue negatively? Methods We performed searches in PubMed, Scopus, and Science Citation Index to review the development of vitamin E-stabilized UHMWPEs and their feasibility as clinical implants.Results The rationale for using vitamin E in UHMWPE was twofold: improving oxidation resistance of irradiated UHMWPEs and fatigue strength of irradiated UHMWPEs with an alternative to postirradiation melting. Vitamin E-stabilized UHMWPE showed oxidation resistance superior to that of irradiated UHMWPEs with detectable residual free radicals. It showed equivalent wear and improved mechanical strength compared to irradiated and melted UHMWPE. The biocompatibility was confirmed by simulating elution, if any, of the antioxidant from implants.Conclusions Vitamin E-stabilized UHMWPE offers a joint arthroplasty technology with good mechanical, wear, and oxidation properties. Clinical Relevance Vitamin E-stabilized, irradiated UHMWPEs were recently introduced clinically. The rationale behind using vitamin E and in vitro tests comparing its performance to older materials are of great interest for improving longevity of joint arthroplasties.

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Section: The Rationale For Using the Antioxidant Vitamin Ementioning

confidence: 67%

Vitamin E-stabilized UHMWPE for Total Joint Implants: A Review

Bracco

Oral

2011

Clinical Orthopaedics &Amp; Related Research

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256

162

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“…It is proposed that this is due to the reaction of vitamin E with the primary free radicals on the polyethylene chains and also free radicals resulting from their reaction with oxygen. A study looking specifically at the stabilising effect of vitamin E in vitamin-E-diffused, irradiated UHMWPE showed higher oxidative stability than unstabilised, irradiated UHMWPE over seven months in air at room temperature and in water at 40°C [54] (showing similar trends at 36 months; Fig. 4; [65]).…”

Section: Dopingmentioning

confidence: 87%

“…But, a terminal sterilisation by gamma irradiation is used currently in clinically available implants prepared using this method (Fig. 3c), resulting in substantially detectable free radicals in this material (3.5 × 10 16 spins/g compared to 11.7 × 10 16 spins/g for 100-kGy irradiated UHMWPE; [54]). Despite the presence of these Fig.…”

Section: Preparation Of Radiation Crosslinked Vitamin E-diffused Anmentioning

confidence: 99%

Vitamin E diffused, highly crosslinked UHMWPE: a review

Oral

Muratoglu

2010

International Orthopaedics (SICOT)

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Highly crosslinked UHMWPE has become the bearing surface of choice in total hip arthroplasty. First generation crosslinked UHMWPEs, clinically introduced in the 1990s, show significant improvements compared to gamma sterilised, conventional UHMWPE in decreasing wear and osteolysis. These crosslinked UHMWPEs were thermally treated (annealed or melted) after irradiation to improve their oxidation resistance. While annealing resulted in the retention of some oxidation potential, postirradiation melted UHMWPEs had reduced fatigue strength due to the crystallinity loss during melting. Thus, the stabilisation of radiation crosslinked UHMWPEs by the diffusion of the antioxidant vitamin E was developed to obtain oxidation resistance with improved fatigue strength by avoiding post-irradiation melting. A two-step process was developed to incorporate vitamin E into irradiated UHMWPE by diffusion to obtain a uniform concentration profile. Against accelerated and real-time aging in vitro, this material showed superior oxidation resistance to UHMWPEs with residual free radicals. The fatigue strength was improved compared to irradiated and melted UHMWPEs crosslinked using the same irradiation dose. Several adverse testing schemes simulating impingement showed satisfactory behaviour. Peri-prosthetic tissue reaction to vitamin E was evaluated in rabbits and any effects of vitamin E on device fixation were evaluated in a canine model, both of which showed no detrimental effects of the inclusion of vitamin E in crosslinked UHMWPE. Irradiated, vitamin E-diffused, and gamma sterilised UHMWPEs have been in clinical use in hips since 2007 and in knees since 2008. The clinical outcome of this material will be apparent from the results of prospective, randomised clinical studies. IntroductionOsteolysis triggered mainly by ultrahigh molecular weight polyethylene (UHMWPE) wear particles has been one of the major problems in total hip arthroplasty along with instability/dislocation and infection [7]. Highly crosslinked UHMWPEs were developed using high-dose irradiation (50-100 kGy) to decrease the wear rate of UHMWPE [44,46] and have become the standard-of-care after their first decade of service, especially in North America [61].Irradiation causes crosslinking in the amorphous phase of the UHMWPE [33], but also initiates the formation of free radicals in the crystalline phase [23], unable to recombine due to structural limitations, they become trapped for long periods of time [29]. These residual free radicals are believed to migrate to the crystalline/amorphous interface and cause oxidative degradation in the material [16][17][18]59, 69] through a cascade of reactions with oxygen [32,71].In first generation crosslinked UHMWPEs [34], postirradiation thermal treatment was used to increase the oxidation resistance (Fig. 1). One approach was to annealThe studies discussed here were performed by research funding in part from NIH/NIAMS

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“…This is because they offer the most robust solution to date toward the prevention of oxidative degradation of devices as evidenced by the results of artificial aging under aggressive conditions and environments [14,15,17]. The need for improved oxidation prevention has been given further impetus as a result of recent reports of the onset of in vivo oxidation in irradiated and thermally stabilized polyethylene implants containing no stabilizing additives [22,25] that are considered current state-of-the-art materials.…”

Section: Discussionmentioning

confidence: 99%

Spectroscopic and Chromatographic Quantification of an Antioxidant-stabilized Ultrahigh-molecular-weight Polyethylene

Narayan

2015

Clinical Orthopaedics &Amp; Related Research

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Background The oxidative stability of various antioxidant-containing ultrahigh-molecular-weight polyethylene (UHMWPE) formulations has been widely reported. Depending on which specific antioxidant is used, the process by which it is incorporated into UHMWPE, and the amount of the antioxidant incorporated, there could be substantial differences in the material and toxicological properties of the UHMWPE formulation. Pentaerythritol tetrakis (3-[3,5-di tertiary butyl-4-hydroxyphenyl] propionate) (PBHP) has been extensively used as an efficient antioxidant in various applications. However, it has not thus far been used to stabilize UHMWPE in orthopaedic implants. It is therefore important to characterize and verify the concentration and homogeneity of distribution of PBHP in the composition, the chemical consequence of exposure of the antioxidant to gamma irradiation, and to assess the toxicological risk of use by the identification and quantification of leachables before the use of PBHP-containing UHMWPE in implantable devices. Questions/purposes (1) Can the concentration and uniformity of distribution of the antioxidant PBHP in UHMWPE powder and in the consolidated, preirradiated formulation be verified? (2) Can the leachable compounds in the gamma radiation crosslinked PBHP/UHMWPE formulation be identified and quantified? Methods PBHP in GUR 1020 UHMWPE was quantified by Fourier transform infrared (FTIR) and ultraviolet-visible (UV-Vis) spectroscopy. The chemical byproducts generated by gamma irradiation of PBHP were identified using gas chromatography in conjunction with mass spectrometry followed by a second-stage mass spectrometry (GC-MS/ MS). When GC-MS/MS was coupled with Stir Bar Sorptive extraction, leachable components in the UHMWPE formulation were identified and quantified. Results The percent concentration of PBHP in UHMWPE powder was confirmed by UV-Vis spectroscopy and the concentration and uniform distribution of PBHP in UHMWPE after consolidation and before radiation crosslinking was verified through FTIR spectroscopy. GC-MS/ MS analysis enabled the identification and quantification of 16 gamma irradiation byproducts of PBHP. These 16 compounds were verified as potentially leachable compounds in PBHP-stabilized UHMWPE and were found to be well below the safety threshold concern of 150 ng/ device in orthopaedic knee inserts made from PBHP-stabilized UHMWPE. Conclusions Spectroscopic analysis has been successfully used to demonstrate the ability to reliably quantify the amount as well as the distribution of PBHP in UHMWPE in orthopaedic bearings. State-of-the-art chemical extraction and analytical techniques have enabled the identification of the gamma radiation-induced byproducts of PBHP and the quantification of these components as leachables from the PBHP-stabilized UHMWPE formulation. Clinical Relevance Antioxidant-stabilized UHMWPE materials being considered for orthopaedic bearings must

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The effect of α-tocopherol on the oxidation and free radical decay in irradiated UHMWPE

Cited by 132 publications

References 42 publications

Vitamin E-stabilized UHMWPE for Total Joint Implants: A Review

Vitamin E-stabilized UHMWPE for Total Joint Implants: A Review

Vitamin E diffused, highly crosslinked UHMWPE: a review

Spectroscopic and Chromatographic Quantification of an Antioxidant-stabilized Ultrahigh-molecular-weight Polyethylene

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