Causes, Symptoms and Treatment

Metallosis (or metal poisioning) is a condition associated with metal-on-metal implants. It first came to the attention of the general public after DePuy recalled 93,000 hip implants.

Simply having high levels of metal ions in your blood does not mean you have metallosis.

So What Is Metallosis?

All total joint replacements are made up of two parts. To take a hip joint as an example - the femur side may made of metal or ceramic and the pelvic side by metal, ceramic or polyethylene (though not all combinations are possible).

When metal-on-metal hip implants are used the two sides of the implant can rub together and, in doing so, shed tiny metal particles.

It is thought that these tiny bits of metal give rise to a response from the immune system which the soft tissue around them to become inflamed.

Symptoms of Metallosis

If you have had a metal on metal implant and are experiencing the symptoms described below then please seek legal, as well as medical, advice.

The generally accepted symptoms are:-

  • Pain - localised around the implant
  • Pseudo-tumours - these look like tumours but aren't. The cause is fluid collecting at the site.
  • Rash - this indicates necrosis (the death of tissues)
  • Osteolysis - re-absorption of bone into the body)
  • Loosening of the implant
  • Raised levels of cobalt and/or chromium in the blood

There is no agreement as to what the safe levels of metal ions such as chromium and cobalt actually are. The usual level for cobalt is 2.5nmol/L and for chromium 5nmol/L.

Metallosis: Who is at Risk

Different types of body structure put more pressure on the implant, which in turn causes it to wear down faster. Higher risk groups are women, people who are obese or shorter people.

Treatment of Metallosis

Revision surgery is necessary to stop further shedding of metallic particles into the body.

Once the offending implant is removed the levels of cobalt and chromium levels in the blood will start to drop. However the immune system may well show a heightened sensitivity to lower levels of these metals in the future.

Related Links: 

The DePuy recall 
Different types of hip implants 
Other hip replacement complications

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