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.