May the surface roughness of the retrieved femoral head influence the wear behavior of the polyethylene liner?

Abstract

This study was aimed at determining the surface degradation occurred on retrieved ceramic and metallic heads, as well as the influence of the head surface quality on the wear of the polyethylene counterface. To this purpose, 14 ceramic and 14 metallic femoral heads retrieved at revision surgery were examined. Scanning electron microscopic analysis provided visual evidence that some metallic heads presented crescent wear more often than the ceramic ones; the former showed a higher volumetric loss (as determined by Coordinate Measuring Machine) than the latter, but less negative Rsk values. This apparent lack of correlation between volumetric loss (i.e., wear factor) and roughness data may be explained by considering that they are two temporally variant parameters. No significant differences were observed between the Ra values of the two sets of femoral heads. The cups articulating against metal heads were characterized by higher mean wear volumes than those articulating against alumina although this difference was not statistically significant; metal heads displayed significantly higher mean wear volumes than alumina heads. The micro-Raman analysis of the cup articulated against the most worn alumina femoral head showed an orthorhombic into monoclinic phase transformation that was not observed in the cups coupled to metal heads. The obtained results showed that the surface finishing of the femoral head (in terms of Rsk values) determined the morphological changes experienced by the ultra-high-molecular-weight polyethylene crystalline phase at the molecular level. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1374-1385, 2016.

More wear‐resistant and ductile UHMWPE composite prepared by the addition of radiation crosslinked UHMWPE powder

“…In this case, a thin film is transferred to the friction component after a brief application of friction, decreasing the wear . However, the high‐dose‐irradiated X‐UHMWPE existed as particles in the composites exposed after a brief application of friction, which increased the roughness of the contact surface and damaged the transferred film existed on surface of friction component . This phenomenon became serious especially at a high content of filler .…”

Wear testing of a canine hip resurfacing implant that uses highly cross‐linked polyethylene

“…) was fifteen times greater than the standard roughness of femoral heads used in human studies ( R a = 0.05 μm). This explanation seems justified, since wear and morphological changes in highly cross‐linked polyethylene liners have been shown to rapidly increase with small rises in femoral head surface roughness . The reason a high surface roughness was selected for our study was to provide a “worst‐case” scenario to rigorously test whether the thin cross‐linked polyethylene liners would experience excessive wear or fracture during testing.…”

“…This explanation seems justified, since wear and morphological changes in highly cross-linked polyethylene liners have been shown to rapidly increase with small rises in femoral head surface roughness. 50, 53 The reason a high surface roughness was selected for our study was to provide a “worst-case” scenario to rigorously test whether the thin cross-linked polyethylene liners would experience excessive wear or fracture during testing. It’s important to note that any comparison between the wear behavior of human and canine THA should be treated with caution, as intrinsic differences exist in joint kinematics, loading magnitudes, and implant sizing.…”