Publications & Reports

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5th UHMWPE International Meeting Presentation: Can Vitamin E be an Alternative to Remelting of HXLPE?

This invited lecture by Prof. Luigi Costa from the University of Torino covers the state-of-the-art for Vitamin E stabilization of HXLPE. Professor Costa's research addresses the question whether or not stabilization of UHMWPE by blending with VItamin E can replace thermal stabilzation of HXLPEs. Dr. Costa provides a technical rationale for eliminating heat treatment of HXLPEs and concludes that Vitamin E can be an effective alternative to remelting of medical grade HXLPEs.

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

Researchers from the University of Torino and Massachussets General Hospital have compiled a review of Vitamin E used in UHMWPE. The review addressed the following questions: (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? And (3) is vitamin E expected to affect the periprosthetic tissue? The authors conclude that vitamin E-stabilized UHMWPE offers a joint arthroplasty technology with good mechanical, wear, and oxidation properties.

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History and Systematic Review of Wear and Osteolysis in Highly Crosslinked UHMWPE

Many previous studies have reported on the radiographic wear and incidence of osteolysis for HXLPE in joint arthroplasty. However, analytical techniques; clinical study design and follow-up; HXLPE formulation and implant design characteristics; and patient populations differ substantially among investigations, complicating a unified perspective on the effect of HXLPE formulation on radiographic wear and incidence of osteolysis. Researchers from Exponent and Drexel University have summarized the historical context of first-generation HXLPE and systematically reviewed the radiographic wear data and incidence of osteolysis for HXLPE in hip and knee arthroplasty.

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Thermal and Dynamic Mechanical Analysis of Vitamin E-Blended UHMWPE

Researchers from the University of Zaragoza studied the effects of vitamin E on the molecular dynamics and microstructural properties of UHMWPE. They hypothesized that the antioxidant would plasticize UHMWPE. However, no plasticizing effects of vitamin E on the molecular dynamics of UHMWPE could be confirmed from mechanical spectroscopy data. The alpha relaxation was modified in intensity and location due to the changes in the degree of crystallinity introduced by the incorporation of vitamin E.

 

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PhD Dissertation - Investigations of Polyethylene Damage Modes of Lumbar Total Disc Replacement

This PHD dissertation outlines several studies that evaluated the biomechanics of total disc replacement. Specifically, an in situ model of lumbar total disc replacement impingement was generated and validated based on clinical data from retrieved polyethylene implants. The clinical parameters associated with impingement sensitivity were also determined in order to provide better guidance to both clinicians and designers.

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Reasons for Revision of First-Generation Highly Cross-Linked Polyethylenes

Over a 10-year period, researchers from Drexel University prospectively evaluated the reasons for revision of contemporary and highly cross-linked polyethylene formulations in a multicenter retrieval program. The most frequent reasons for revision were loosening, instability, and infection and were not related to polyethylene formulation. This retrieval study including first-generation highly cross-linked liners demonstrated lower wear than conventional polyethylene. Although loosening remained as the most prevalent reason for revision, researchers could not demonstrate a relationship between wear and loosening.

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PhD Dissertation: Design of Surface with Hydration Lubrication of UHMWPE by Phospholipid Polymers

The goal of this study was the creation of an artificial hip joint based on a novel concept of “hydration lubrication” by using poly(MPC) (PMPC)-grafted onto the surface of crosslinked polyethylene (PMPC-grafted CLPE); this device is designed to reduce wear and suppress bone resorption. In this thesis, the bearing surface with PMPC in artificial hip joints is assumed to have a brush-like structure similar to that of articular cartilage. The hydration lubrication interface can therefore be regarded to mimic the natural joint cartilage in vivo.

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ASTM Vitamin E Index Interlaboratory Study

This memo summarizes the results of a two-phase research program undertaken as by the ASTM working group to evaluate the suitability of transmission FTIR to characterize the levels of Vitamin E in medical grade UHMWPE. Based on measurements conducted in Phase 1 and Phase 2 of this interlaboratory research program, we conclude that transmission FTIR does not provide sufficiently repeatable and reproducible results for UHMWPE blended with concentrations of vitamin E of up to approximately 1,200 ppm. Conversely, reasonable repeatable and reproducible results were achieved with 5,000 ppm concentration of Vitamin E in UHMWPE as documented in the Phase 1 interlaboratory study.

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2010 ORS Short Talk: The Effect of 2nd Generation Barrier Packaging on Polyethylene for Total Disc Replacement

First-generation barrier packaged and gamma sterilized in air components have been shown to oxidize in vivo, however, the efficacy of current Depuy Spine metal foil-based packaging remains unknown. The objective of this study was to expand our previous studies of UHMWPE oxidation and oxidation potential to 2nd generation foil-based packaging. The hypothesis was that foil-based packaging would reduce oxidation and oxidation potential when compared to historical packaging techniques.

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2010 ORS Poster: Comparison of First- and Second- Generation Annealed Polyethylenes for Total Hip Arthroplasty

Recently, 2nd-generation highly crosslinked polyethylenes were introduced to address concerns of rim fracture in remelted highly crosslinked polyethylenes and high levels of rim oxidation in annealed highly crosslinked polyethylenes. The objective of this study was to compare 2nd-generation sequentially annealed polyethylene liners with 1st-generation annealed liners after short-term implantation. The hypothesis was that sequentially annealed liners would have lower oxidation than annealed liners, while maintaining similar reasons for revision, wear resistance, and mechanical properties.

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