Publications & Reports

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Oxidation of Radiation-Sterilized UHMWPE Components in a Low Oxygen Environment

In the present study, the early stages of oxidation were investigated by assessing the hydroperoxide levels and distribution within a selection of ready-to-use UHMWPE prosthetic components. Hydroperoxides were detected in all samples, despite the sterilisation in inert atmosphere. Three different types of behaviour were identified and discussed. A correlation with the packaging and sterilisation conditions was proposed.

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Influence of Remelting on Fatigue Behavior of E-Beam Irradiated UHMWPE

Currently used post-irradiation thermal treatments, which aim to decrease the free radicals within the material, introduce microstructural changes that affect UHMWPE mechanical properties, particularly the fatigue strength. This study was planned to evaluate the influence of UHMWPE remelting after irradiation on the fatigue resistance of the material.

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Effects of Annealing and Remelting on Fatigue Crack Propagation of Crosslinked UHMWPE

The objective of this study was to evaluate the effects of gamma radiation-induced crosslinking with two different post-irradiation thermal treatments on the FCP resistance of UHMWPE. Crosslinking was found to decrease the ability of UHMWPE to resist crack inception and propagation under cyclic loading. The findings also suggested that annealing as a post-irradiation treatment may be somewhat less detrimental to FCP resistance of UHMWPE than remelting.

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Analysis of Retrieved Crossfire Liners

This study reports on detailed analyses of retrieved, annealed crosslinked liners. Slight variation in properties was observed as a function of sampling location, with the properties near the unworn surface displaying the greatest relative variability. The authors concluded that the variability in polyethylene properties was not clinically significant.

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Chemical Co-Agents Enhance Radiation Crosslinking of UHMWPE

Researchers from the University of Torino have investigated the effect of unstaturated additives on the crosslinking behavior of UHMWPE. 1,7-octadiene turned out to be the most effective additive for the present purpose, exhibiting a good efficiency in enhancing crosslinking. FTIR analyses showed that consumption of vinyl double bonds is proportional to the irradiation dose, with an efficiency which increases with increasing their initial concentration, confirming the hypothesis of the involvement of these groups in the crosslinking process.

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Prevalence of Primary and Revision Total Hip and Knee Arthroplasty in the United States

The purpose of this study was to quantify the procedural rate and revision burden of total hip and knee arthroplasty in the United States. The number and prevalence of primary hip and knee replacement procedures increased substantially between 1990 and 2002, but the trend was considerably more pronounced for primary total knee arthroplasty. The reported prevalence trends have important ramifications on the number of expected joint replacement surgeries to be performed by orthopedic surgeons in the future.

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Validación del análisis de MicroCT de reemplazos de cadera

En este estudio se introdujo y validó una técnica nueva basada en tomografía computarizada "microCT" para evaluar el desgaste en revestimientos acetabulares recuperados. El error general de escaneo se cuantificó en forma gravimétrica y se asoció con una incertidumbre máxima de 0,6%. Los análisis de incertidumbre de intra e interobservador demostraron que el método es preciso y repetible.

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Crystallinity Changes in Crosslinked UHMWPE During Compression

This study examines the effect of a large compressive plastic deformation on the melt temperature (Tm), lamellar thickness, crystallinity, and density of conventional and highly crosslinked UHMWPE. The microstructural evolution during compressive deformation was found to be a function of UHMWPE formulation, as affected by irradiation and postirradation heat treatment.

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In Vivo Degradation of Polyethylene Liners after Gamma Sterilization in Air

The purpose of this study was to quantify the extent to which the mechanical properties and oxidation of conventional polyethylene acetabular liners treated with gamma sterilization in air change in vivo. On the average, the rim and the unloaded bearing showed evidence of severe oxidation near the surface after long-term in vivo aging, but these trends were not typically observed on the loaded bearing surface or near the backside of the liners.

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Validation of MicroCT Wear Analysis of Hip Replacements

In this study, a novel microCT based technique for evaluating wear in retrieved acetabular liners was introduced and validated. Overall scanner error was quantified gravimetrically and associated with a maximum uncertainty of 0.6%. Intra- and inter-observer uncertainty analysis showed the method to be both accurate and repeatable.

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