Publications & Reports

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3rd UHMWPE International Meeting Presentation: Ion Implantation of Highly Crosslinked and Remelted UHMWPE

Investigators from the University of Zaragoza implanted highly crosslinked and remelted UHMWPE with N and He ions at different ion fluences. Mechanical and tribological properties under distilled water lubrication at body temperature were assessed after ion implantation by means of microhardness and pin-on-disk tests respectively. The influence of the ionic species, and implantation dose on surface hardness, friction coefficient and wear factor were characterized.

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3rd UHMWPE International Meeting Presentation: On the Novel Use of Nitroxides and Alpha-Tocopherol as Radiolytically-Produced Free Radical Scavengers in UHMWPE

Researchers from the University of Maryland have compared alpha-tocopherol (Vitamin E) with nitroxides as electron-transfer radical scavengers. Nitroxides (RRNO) are stable organic compounds that are able to reduce to hydroxylamines and oxidize to oxoammonium cations. These reactions are reversible and can be exploited to yield a novel radical scavenger in UHMWPE.

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3rd UHMWPE International Meeting Presentation: 15-Year Experience in Analysis of UHMWPE: State of the Art and Future Perspectives

During the last 15 years, researchers from Torino have had the opportunity to analyze more than 700 UHMWPE prosthetic components (hip, knee and shoulder). Diffusion of polar compounds from the synovial fluid into polyethylene was observed in the majority of the retrieved samples. The nature of these products has been investigated along with their possible influence on the mechanical properties of the polymer. In the last five years, the researchers have studied a significant number of crosslinked polyethylenes, both new and retrieved. The results of this study indicate that the variables of the crosslinking process can greatly influence final material properties and that not all crosslinked polyethylenes are the same.

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3rd UHMWPE International Meeting Presentation: Trace Concentrations of Vitamin E Protect Radiation Crosslinked UHMWPE from Oxidative Degradation

Our objective was to determine the minimum Vitamin E concentration necessary to protect conventional and highly crosslinked UHMWPE from a severe, in vitro oxidative challenge. Trace concentrations (0-500 ppm) of a-tocopherol (Vitamin E) were blended with GUR 1020 and 1050 resins and compression molded into sheets. 10 mm-thick blocks were divided into three groups: (1) no irradiation (control); 30 kGy of gamma irradiation in nitrogen; and (3) 75 kGy of gamma irradiation in air. The minimum concentration of Vitamin E needed to stabilize UHMWPE during our accelerated tests depended upon the method of radiation processing.

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In Vivo Oxidation of Gamma-Barrier-Sterilized Polyethylene Bearings

Researchers from the Thayer School of Engineering in Dartmouth College have studied polyethylene stored in gamma-barrier packaging before and after implantation. The series of gamma-barrier retrievals studied suggests that oxidation occurs in the body via the same mechanism as seen in gamma-air-sterilized bearings. A critical oxidation level is identified above which polyethylene bearings are susceptible to fatigue damage after sufficient cycles of use. Although critical oxidation was not reached in the majority of the retrieved gamma-barrier bearings studied, in vivo oxidation appears to follow an exponential increase with time.

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Wear Resistance and Mechanical Properties of Vitamin E Doped Acetabular Inserts

Researchers from MGH have evaluated the wear resistance and mechanical behavior of vitamin E-doped, highly crosslinked UHMWPE acetabular inserts. The doped inserts exhibited a four to ten-fold decrease in wear rate from that of conventional UHMWPE. The data indicate good wear properties and improved mechanical and fatigue properties for vitamin-E stabilized cross-linked UHMWPE.

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Fotogrametría digital para el análisis cuantitativo del desgaste en componentes recuperados de artroplastías totales de rodilla

Investigadores en la Universidad de Drexel idearon un método fotogramétrico digital para cuantificar la extensión del daño superficial en componentes recuperados de reemplazos totales de rodilla. La precisión general de las mediciones de área fue del 97,8%. Se determinó que el método fotogramétrico es razonablemente preciso y repetible al medir áreas bidimensionales y que es aplicable a la determinación del desgaste. No hubo ninguna variación significativa en la incertidumbre detectada entre diferentes diseños de implantes.

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Review of Oxidative Stability, Mechanical Behavior, and Biocompatibility of Alpha-Tocopherol in UHMWPE

Recently, alpha-tocopherol (Vitamin E) doped UHMWPE has received increased attention as a novel orthopedic UHMWPE. Alpha-tocopherol doped UHMWPE exhibits excellent wear and fatigue performance and can be applicable to high stress and linear motion applications, such as total knee replacements (TKR). This paper comprehensively reviews recent advances in the mechanical properties, oxidation stability, and biocompatibility of medical grade UHMWPE, particularly focusing on highly crosslinked UHMWPE and alpha-tocopherol doped UHMWPE.

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Logistics and Implementation of a Multi-Center, Regional Total Hip Replacement Retrieval Program to Investigate In Vivo Oxidation of Polyethylene

Researchers have developed a prospective retrieval collection program for specific types of retrieved implants for clinical evaluation and subsequent characterization of mechanical and physical properties. This paper focuses on the logistics and implementation of a multi-center, regional total hip replacement retrieval program to investigate in vivo oxidation of polyethylene. The organizational structure detailed in this manuscript may hopefully be generalized to other multi-institutional retrieval programs that are motivated to answer a specific research question.

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3rd UHMWPE International Meeting - Polyethylene in Total Joint Replacement Systems: Concerns and Solutions

This is the announcement for a two-day meeting in Madrid, which is planned for September 14-15, 2007. The meeting is in two main parts: one basic research module, open for papers and oriented to gather cutting-edge research on UHMWPE; and a second part oriented to clinical aspects and discussion. Additional details about the conference can now be found at the conference website: http://www.facing-bcn.com/uhmwpe2007/.

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