DISCUSSIONS on FACEBOOK
Publications & Reports
Latest Lessons Learned from Retrieval Analyses from UHMWPE and Alternative Bearing Total Disc Replacements
This review addresses the following four main questions: 1) What are the latest lessons learned from polyethylene in large joints and how are they relevant to current total disc replacements (TDRs)? 2) What are the latest lessons learned regarding adverse local tissue reactions from metal-on-metal, CoCr bearings in large joints and how are they relevant to current TDRs? 3) What advancements have been made in understanding the in vivo performance of alternative biomaterials, such as stainless steel and polycarbonate urethane, for TDRs in the past five years? 4) How has retrieval analysis of all these various artificial disc bearing technologies advanced the state of the art in preclinical testing of TDRs? The study of explanted artificial discs and their associated tissues can help inform bearing selection as well as the design of future generations of disc arthroplasty.
AuthorKurtz SM et al.
SourceSeminar Spine Surg
Year2011
5th UHMWPE International Meeting Presentation: Oxidation Initiated by Cyclic Loading in the Presence of Lipids
By coupling the adverse effects of thermal aging with mechanical stress and lipid initiated oxidation, researchers from MGH in Boston sought to investigate if either irradiated and melted PE or vitamin E stabilized PE was prone to environmental stress cracking (ESC). The researchers hypothesized that the active protection of vitamin E was necessary to protect highly crosslinked PEs under such unfavorable conditions. Oxidation initiated by cyclic loading and by the presence of an unstable lipid can cause a loss of stability, even in materials containing no residual free radicals such as CISM-100. The active protection granted by antioxidants such as vitamin E may be necessary to combat oxidation in the long term in vivo.
SourceTrans 5th UHMWPE
Year2011
5th UHMWPE International Meeting Presentation: UHMWPE/Multiwall Carbon Nanotubes Composites
The aim of this work is to enhance the antioxidant capacity of carbon nanotubes and their ability to act as free radical scavengers in UHMWPE. EPR spectroscopy reveals that the presence of CNT has a significant influence in radical formation during the radiation treatment, being this effect more pronounced in the case of the allyl radical. CNTs reduced the oxidation index when the irradiated nanocomposite was subjected to accelerated aging. Both outcomes point out the capability of the nanotubes to act as free radical scavengers when the nanocomposite is irradiated.
AuthorMartínez-Morlanes et al
SourceTrans 5th UHMWPE
Year2011
5th UHMWPE International Meeting Presentation: Evaluation of Oxidation in Virgin UHMWPE Knee Components after Retrieval and Shelf Aging
The primary purpose of this study was to determine if retrieved, virgin UHMWPE knee components are susceptible to either in-vivo or ex-vivo oxidation. Additional goals in this study included evaluations of (a) the distributions and qualitative amounts of lipids within the retrieved components, and (b) the relationship between the peak-height and peak-area oxidation indices. Esterified fatty acids (EFAs) were found at all of the surfaces examined with concentrations and penetration depths that appeared to be related to both mechanical loading and the exposure to synovial fluid. Evaluation of hexane extraction for both 16 and 32 hours demonstrated that all of the extractable species were successfully removed after 16 hours of extraction.
AuthorMorrison M, et al.
SourceTrans 5th UHMWPE
Year2011
5th UHMWPE International Meeting Presentation: Relationship Between in Vivo Stresses and Oxidation of UHMWPE
The aim of this study is to demonstrate that stress induced by the in vivo joint forces on EtO sterilised UHMWPE components is responsible of an increased oxidation of the material. The experimental data collected in this study indicate that, as expected, there is a correlation between the observed global wear and in vivo time, although anatomic conditions, patient activity and retrieval motivations could seriously affect the reproducibility of the phenomenon in such a differentiated sample outline.
AuthorRegis et al.
Source5th Trans UHMWPE
Year2011
5th UHMWPE International Meeting Presentation: Impact of Aging Environment on the Oxidation of Vitamin E Blended UHMWPE
Researchers have investigated a new Vitamin E blended, highly crosslinked UHMWPE material in both standard accelerated environments, and in an accelerated bovine synovial fluid (BSF) environment at 60 °C under 5 atm O2. Aging results for Vitamin E blended UHMWPE (“VE-PE”) have shown improved stability compared to earlier generation materials. BSF provides an interesting aggressive accelerated aging environment that creates a different oxidation profile in conventional materials as compared to the standard aging environments. In BSF, conventional material oxidized over time mainly in the bulk rather than at the surface.
AuthorBerlin et al
SourceTrans 5th UHMWPE
Year2011
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.
AuthorLee M, et al.
SourceTrans 5th UHMWPE
Year2011
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.
AuthorMarshall AD, et al.
SourceTrans 5th UHMWPE
Year2011
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.
AuthorBladen, C
SourceTrans 5th UHMWPE
Year2011
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.
AuthorOral E et al.
SourceTrans 5th UHMWPE
Year2011