Publications & Reports

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5th UHMWPE International Meeting Presentation: Imaging intra-Cellular UHMWPE Wear Debris with Coherent Anti-Stokes Raman Scattering Spectroscopy

Researchers from the University of Edinburgh have investigated the use of coherent anti-Stokes Raman scattering spectroscopy (CARS) as a method of imaging ingested polyethylene particles in macrophages in three dimensions. CARS is used as a label free method of imaging cells and tissues, relying on chemical contrast generated by different vibrational modes in molecules.

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5th UHMWPE International Meeting Presentation: Effect of UHMWPE Particles on Mesenchymal Stem Cell Replication

Investigators from the University of Texas Health Science Center at San Antonio have studied the effect of UHMWPE on mesenchymal stem cells (MSC). UHMWPE particles had a dose dependent effect on MSC replication. The particles were stimulatory to MSC replication up to a threshold dose. At a dose above 1x10^7 particles/ml, this debris became deleterious to the stem cell.

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5th UHMWPE International Meeting Presentation: Anti-Inflammatory Properties of Vitamin E Reduce Inflammatory Response to Wear

The aim of this study, conducted at the University of Leeds, was to stimulate TNF-α release in vitro using lipopolysaccharide (LPS) or clinically relevant wear particles (UHMWPE or PVE) and investigate the effect of VE as an antiinflammatory. Results confirmed that VE modulates the response of LPS-stimulated monocytes to produce lower levels of TNF-α compared to control LPS-stimulated monocytes. This trend is also observed when VE is added topically to UHMWPE stimulated PBMNCs. Wear particles generated from UHMWPE containing 1000ppm VE also produced lower levels of TNF-α.

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5th UHMWPE International Meeting Presentation: Crosslinked Vitamin E Blends with Improved Grafting and Wear Resistance

In this study, researchers from MGH determined the amount of grafting in vitamin E-blended and irradiated UHMWPE. It was hypothesized that increasing irradiation temperature would increase crosslinking despite decreasing vitamin E potency due to degradation at the higher temperature. While radiation crosslinking of vitamin E-blended UHMWPE decreases crosslinking compared to virgin UHMWPE and also decreases the vitamin E in UHMWPE for long-term oxidative stability, it also results in increased grafting of the antioxidant on the polymer, presumably resulting in longer-term stability. Moreover, warm irradiation allowed for increased preservation of the antioxidant, increased grafting, increased cross-linking and decreased wear. This result is significant for the wear and oxidation stability of stabilized UHMWPE joint implants.

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5th UHMWPE International Meeting Presentation: Development of Vitamin E Containing UHMWPE Grades

Ticona has developed, validated and commercialized two new UHMW-PE grades based on the existing, commercially available Type 1 and Type 2 UHMW-PE grades. Right from the beginning, the governing idea of the development was to offer a material that can be processed in the same way as the existing grades GUR 1020 and GUR 1050 and offers identical mechanical properties but with an improved oxidation resistance. These new grades are called GUR 1020-E and GUR 1050-E.  As is shown here, the mechanical properties of the grades are still identical to the existing GUR grades without vitamin E.

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5th UHMWPE International Meeting Presentation: Risk Assessment of the Biocompatibility of Vitamin E Blended UHMWPE

The objective of this study was to evaluate the vitamin E blended UHMWPE used in StelKast’s EXp acetabular liner to determine if the vitamin E preblended in UHMWPE matrix was susceptible to elution after radiation crosslinking. Secondly, if vitamin E could be eluted from the UHMWPE, the extract was analyzed to determine if any vitamin E degradation products were present. In parallel, a series of ISO 10993 protocols were conducted to assess the biocompatibility of the material. The biocompatibility of the GUR 1020-E acetabular liner material was assessed for genotoxicity, cytotoxicity, irritation and sensitization. For all tests the EXp material was found to be biocompatible and without adverse effects that could pose a potential human health risk.

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5th UHMWPE International Meeting Presentation: Network Parameters for UHMWPE using Plane Strain Compression

In this study, researchers from Brigham and Women’s Hospital compared two constitutive models governing the large strain deformation of polymers to describe the plane strain compression of unirradiated (control) and irradiated PE, and extracted molecular level parameters such as effective crosslink density and molecular weight between crosslinks. This study demonstrates that this characterization technique is an effective alternate method to characterize the network parameters of orthopedic grade PE.

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5th UHMWPE International Meeting Presentation: Decreased Functional Biological Activity of XLPE Wear Debris

Researchers from Drexel University investigated differences in the size, shape, number and biological activity of polyethylene wear debris obtained from primary THA revision surgery of conventional, gamma inert sterilzed UHWMPE versus remelted or annealed HXLPE acetabular liners. In this in vivo study, researchers found a significantly decreased HXLPE wear debris number. Overall, the predicted osteolytic potential of wear debris generated by HXLPE liners in vivo is significantly reduced by the improvements in polyethylene wear resistance.

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5th UHMWPE International Meeting Presentation: Cytotoxic Effects of Antioxidants for UHMWPE

The aim of this study was to investigate the effects of UHMWPE anti-oxidant compounds on the cell viability of a human histiocytic cell line and peripheral blood mononuclear cells (PBMNCs) in vitro. The cytotoxicity of several anti-oxidant
compounds was investigated and compared to vitamin E. These included HPA01, a hindered phenol; TEMPO, a nitroxide; and the lanthanides Europium (II) and Europium (III).This study reveals that the majority of these compounds are toxic to human monocytic cells at relatively low doses, however, it is not known whether these compounds will leach from the polymer in vivo and therefore pose a cytotoxic risk.

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5th UHMWPE International Meeting Presentation: Bacterial Adherence to UHMWPE

In this study, researchers from Madrid aim to verify the adherent microorganisms from different components in retrieved implants from infected joint replacements, particularly the bacterial adherence on UHMWPE components compared with other materials, in hip and knee components retrieved from infected arthroplasties. UHMWPE significantly adhered less microorganisms than other materials in arthroplasty components. This is of particular clinical interest, as the exchange of UHMWPE components is frequent when dealing with early infections, but the effectiveness of this gesture is controversial. Researchers concluded that other components rather than UHWMPE are at similar or greater risk of adhering and maintaining microorganisms in an infected arthroplasty.

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