The influence of inert packaging on the shelf ageing of gamma-irradiation sterilised ultra-high molecular weight polyethylene

Biomaterials ◽  
2003 ◽  
Vol 24 (1) ◽  
pp. 139-145 ◽  
Author(s):  
S Lu ◽  
J.F Orr ◽  
F.J Buchanan
Keyword(s):  
Molecular Weight ◽  
Gamma Irradiation ◽  
High Molecular Weight ◽  
Ultra High Molecular Weight

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.

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