http://www.mydepuyhiprecall.com/2011/07/review-of-cell-biology-surrounding.html (series of about 10 articles on this topic.) Again in 2011 a compilation of the Evidence So Far appeared in the Journal of Bone and Joint Surgery. This was also published by the Department of Orthopaedics, University College
Chemical speciation of nanoparticles surrounding metal-on-metal hips
Spectromicroscopy of tissue surrounding failed CoCr metal-on-metal hip replacements detected corroded nanoscale debris in periprosthetic tissue in two chemical states, with concomitant mitochondrial damage. The majority of debris contained Cr3+, with trace amounts of oxidised cobalt. A minority phase containing a core of metallic chromium and cobalt was also observed.