Seems rather strange

Medical regulators are drawing up new advice for more than 30,000 Britons who have received “metal-on-metal” devices because of fears that they are even more dangerous than previously thought, a Sunday Telegraph investigation has found.

Problems occur with such devices when friction between the metal ball and cup causes minuscule metal filings to break off, which can seep into the blood and cause inflammation, destroying muscle and bone.

There are also concerns that the fragments could put the nervous system, heart and lungs at risk of being slowly poisoned.
…..
tests to establish the levels of cobalt and chromium in their blood,

Err, why are levels of cobalt and chromium to be tested? The usual metal for such implants is titanium.

Co and Cr would be strange metals to use in the first place: given that they can indeed be toxic inside the blood system. I\’ve had a look around and I cannot find anything about what metals these implants are in fact made from: Ti, Ta or Nb sound to me like the most likely ones for they are, as far as the human body is concerned, inert.

The presence of Co and or Cr indicates that they were, or at least are being assumed to be, made from a high grade stainless steel (Co perhaps substituting for Ni). Which sounds like a slightly odd thing to make implants from.

Anyone got more info?

Update, note first comment. CoCrMo alloys are used for implants. Seems a bloody strange alloy to use but then what the hell do I know?

4 comments on “Seems rather strange

  1. My mother’s knee replacement was very problematic as they first had to source a cobalt-free alloy for the joint as she is allergic.

  2. Back before the flood, around 1957 or so, my maternal Aunt, yes Aunt, was allowed a special allocation of stainless steel from which to machine prototype hip joints for surgeons at the RUH here in Bath. Most of the alloying ingredients for the steel were still on the ‘Military only’ ration list and mainly reserved by the US. My Aunt, an intreaguing lady, ran an engineering prototyping buisiness for the hospitals; I well remember going on a Sunday morning, in her Bristol 400, round the waqrds collecting scalpels for resharpening and other bits of surgical equipment that needed repair, redesign etc.

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