Cobalt and chromium measurement in patients with metal hip prostheses.

Approximately 1 million metal-on-metal (MoM) hip prostheses have been implanted worldwide to alleviate pain, restore hip function, and improve overall quality of life. These implants contain femoral and acetabular bearing surfaces that are typically composed predominantly of cobalt (Co) and chromium (Cr). Although the majority of MoM hip replacements have been successful, multiple recent reports have documented markedly increased Co and Cr concentrations in the joint synovial fluid, periprosthetic tissue, blood, and even peripheral tissues of some patients with MoM hip prostheses. Consequently, concerns have been raised about the physiological consequences of metal release from MoM hip prostheses into the periprosthetic tissue and systemic circulation.