Influence of scratch damage to S phase coated and uncoated orthopaedic grade stainless steel on wear of ultrahigh molecular weight polyethylene

摘要

The aim of the present paper was to quantify the significance of uncoated and S phase coated medical grade stainless steel (MGSS) surfaces with simulated scratch dimensions, akin to those generated in vivo, on the overall ultrahigh molecular weight polyethylene (UHMWPE) wear factor, i.e. to establish whether or not scratch lips generated under physiologically relevant loading conditions serve to augment the overall wear factor produced by the mean plate asperity heights of the polished metallic counter surfaces. A 29% increase in UHMWPE wear factor was produced when sliding against non-scratched N19 S phase coated MGSS compared to those obtained when apposing uncoated MGSS. This was attributed to the tested coated surfaces having ~1.7 times more microasperities per 50 ìm test length in the direction of sliding contact compared to the uncoated surfaces. A validated experimental procedure for creating Scratched metallic surfaces with dimensions (lip heights and groove depths) towards the upper bound of those observed on MGSS explants was used to show that a critical minimum threshold scratch lip height must be reached before it influences the UHMWPE wear factor beyond that due to the interaction with the microasperities alone.