Data-Driven Innovations in Joint Replacement: Do Ceramic Femoral Heads Contribute to Polyethylene Oxidation?

Renewed attention is being paid to biomaterials used in total hip arthroplasty (THA) given the continued clinical problems of osteolysis and aseptic loosening which result from the long-term wear of acetabular polyethylene (PE) bearing surfaces. One advantage of using ceramic femoral heads is low PE wear, presumably because of the ceramics ' bioinert behavior. However, beyond simple mechanical abrasion, marked differences have been found in the degradation of PE when coupled with different ceramic materials. This study examined the surface characteristics and performance of oxide-based (zirconia-toughened alumina, ZTA) and non-oxide (silicon nitride, Si3N4) femoral heads. Under articulation, ZTA femoral heads were found to release detectable amounts of oxygen from their surfaces into the tribolayer, which resulted in enhanced PE oxidation. In contrast, femoral heads made from Si3N4 scavenged oxygen from the tribolayer, thereby limiting the degradation of PE. This work is the first to challenge the assumption that ceramic materials are inherently stable in vivo, and suggests that the longevity of THA prostheses may depend on the material properties of the ceramic used during surgery. Neglecting these important physical chemistry aspects impedes the scientific development of new materials and favors monopolistic economics in the market, leading to limited choices for surgeons

Ceramics and ceramic coatings in orthopaedics

International audienceno abstrac

Effect of pH and monovalent cations on the Raman spectrum of water: Basics revisited and application to measure concentration gradients at water/solid interface in Si3N4 biomaterial

The effect of hydrogen carbonate (HCO3-) and cations (Na+, K+) solvated in water were revisited according to high spectrally resolved Raman measurements. Water solutions with different bicarbonate concentrations or added with increasing amounts of monovalent cations were examined with respect to their Raman spectra both in the bulk state and at the solid/liquid interface with a silicon nitride (Si3N4) bioceramic. Spectroscopic calibrations confirmed that the Raman emission from OH-stretching in water is sensitive to molarity variations (in the order of tens of mM). The concentration gradient developed at the solid/liquid interface in cation-added solutions interacting with a Si3N4 surface was measured and found to be peculiar to individual cations. Local variation in pH was detected in ionic solutions interacting with Si3N4 samples, which might represent a useful property for Si3N4 in a number of biomedical applications. (C) 2015 Elsevier B.V. All rights reserved