I think Danny has really good point about allergies to metals/skin allergies vs orthopaedic implants. I would discuss this with one of the top HR surgeons like McMinn, others. There are a few studies that I read awhile back that discusses this issue and I don't recall any evidence that suggested that CoCr implant would be problematic if a person had general metals allergies, which could I think could be caused by a host of different factors. Although, piece of mind is a big thing and I understand the concern.
I recall Pritchett telling me a year ago or so that he was involved with research on ceramic on metal. I don't know where that's at. You could check with his office, maybe. I haven't checked the FDA website on HR lately, but there might some info on it there also.