 BIOLOXdelta is a zirconia toughened alumina ZTA. Along with alumina Al and zirconia Zr, this material also contains traces of chromium Cr, strontium Sr and very low amounts of yttrium Y. This ceramic has an 11-year history of worldwide use in hip arthroplasty, with an excellent track record. Ceramic-on-ceramic bearings consist of the hardest material with the lowest wear rate of all bearing couples used in hip arthroplasty. The very low volume of inert ceramic nanoparticles and the absence of elevated Cobalt Co and Cr ion levels in the bloodstream virtually abolishes the risk of adverse local tissue reactions ALTR, allergic reactions and systemic cobalt toxicity which can complicate some MoM Hip replacements. BIOLOXdelta contains very small amounts of Cr, but Cr release from the material remains below the detection limit in the blood. Strontium ions are found in the blood of control patients without any implant and remain at similar background level in patients with BIOLOXdelta ceramic implants, Yttrium ions are not detected. 