Oxidation-induced dynamic changes in morphology reflected on freeze-fractured surface of gamma-irradiated ultra-high molecular weight polyethylene components

2002 ◽  
Vol 62 (4) ◽  
pp. 540-549 ◽  
Author(s):  
Eiichiro Watanabe ◽  
Masahiko Suzuki ◽  
Kazuya Nagata ◽  
Toshiaki Kaneeda ◽  
Yoshitada Harada ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Dynamic Changes ◽  
Gamma Irradiated ◽  
Ultra High Molecular Weight ◽  
Fractured Surface

Comparison of gas plasma and gamma irradiation in air sterilization on the delamination wear of the ultra-high molecular weight polyethylene used in knee replacements

2000 ◽  
Vol 214 (3) ◽  
pp. 249-255 ◽  
Author(s):  
E A Reeves ◽  
D C Barton ◽  
D P FitzPatrick ◽  
J Fisher
Keyword(s):  
Molecular Weight ◽  
Gamma Irradiation ◽  
High Molecular Weight ◽  
Permanent Deformation ◽  
Ftir Analysis ◽  
Analysis Model ◽  
Gas Plasma ◽  
Knee Replacements ◽  
Gamma Irradiated ◽  
Ultra High Molecular Weight

Early failure of knee replacements is thought to be due to the combination of sterilization by gamma irradiation in air and the high cyclic stresses that they endure during use. Such failures are shown through delamination and permanent deformation of the ultra-high molecular weight polyethylene (UHMWPE) component. This study investigated whether gas plasma sterilization, as an alternative to gamma irradiation in air, would give better performance after ageing in a knee replacement using a metal pin on polymer plate wear test. Fourier transform infrared (FTIR) analysis was performed on the components to assess oxidation levels and a finite element stress analysis model is presented to estimate strain at failure in the UHMWPE. Delamination occurred in the majority of the gamma-irradiated plates but did not occur in any of the gas-plasma-sterilized plates. The FTIR analysis showed that the plates gamma irradiated in air were highly oxidized when compared with the gas-plasma-sterilized plates. Plastic strain at failure was determined for the gamma-irradiated plates and found to be less than 2.4-14 per cent.

Wear Mechanisms of Untreated and Gamma Irradiated Ultra-High Molecular Weight Polyethylene for Total Joint Replacements

2005 ◽  
Vol 127 (2) ◽  
pp. 273-279 ◽  
Author(s):  
J. Zhou ◽  
K. Komvopoulos
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
High Molecular Weight ◽  
Wear Mechanisms ◽  
Irradiation Dose ◽  
Cross Link ◽  
Link Density ◽  
Cross Link Density ◽  
Gamma Irradiated ◽  
Ultra High Molecular Weight

Modification of the surface microstructure of ultra-high molecular weight polyethylene (UHMWPE) is essential for improving the wear resistance of orthopedic implants. A common approach is to cross-link the polymer by gamma irradiation. The objective of this study was to examine the tribological behaviors of untreated and gamma irradiated UHMWPE under physiologically relevant contact conditions. Emphasis was placed on the identification of the dominant wear mechanisms in the early stage of polymer wear. The irradiation dose exhibited a strong effect on the tribological properties of UHMWPE sliding against Co–Cr alloy in a bath of bovine serum. Transmission electron microscopy (TEM) and environmental scanning electron microscopy (ESEM) were used to examine the microstructure and morphology of the worn surfaces. Regularly spaced folds with average spacing depending on the irradiation dose (i.e., cross-link density) formed on the wear tracks. Surface folding was related to plastic flow and the degree of mobility of the crystalline lamellae. SEM and TEM results elucidated the roles of the cross-link density and crystalline lamellae in the wear process. Based on the experimental evidence, a deformation model was obtained that provides explanation for the dependence of surface folding on the cross-link density and lamellae reorientation during sliding.

scholarly journals Gel fraction measurements in gamma-irradiated ultra high molecular weight polyethylene

2003 ◽  
Vol 22 (6) ◽  
pp. 647-649 ◽  
Author(s):  
Amal Elzubair ◽  
João Carlos Miguez Suarez ◽  
Claudia Maria Chagas Bonelli ◽  
Eloisa Biasotto Mano
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Gel Fraction ◽  
Gamma Irradiated ◽  
Ultra High Molecular Weight

Microstructures of ultra high molecular weight polyethylene by SEM

1995 ◽  
Vol 53 ◽  
pp. 500-501
Author(s):  
H. C. Wang ◽  
C. Sung ◽  
J. Hamilton
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Particle Size ◽  
High Molecular Weight ◽  
Optical Transmission ◽  
Transmission Microscopy ◽  
Orthopedic Applications ◽  
Ultra High Molecular Weight ◽  
Fractured Surface ◽  
Small Holes

Ultra high molecular weight polyethylene (UHMWPE) is widely used in many orthopedic applications because of its good mechanical properties and excellent biocompatability. Mechanical properties are related to its ultra-high molecular weight, but the presence of defects in morphology will cause a decrease in these properties. The aim of this study was to characterize the microstructure and microchemistry of so-called “fusion defects”, observed by optical transmission microscopy, using SEM along with EDXS analysis. The fractured surface of UHMWPE was also studied.Defects similar to those found in commercially prepared UHMWPE were detected in the hot-pressed and extruded samples prepared at U-Mass Lowell using GUR 412. They consist of holes or cavities and sometimes appear to be circular in shape and are composed of variously sized small holes. The size of the defects is around 100 μm in diameter which is similar to the particle size of the raw powders.

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