Prosthetic parts used to replace a damaged knee, hip, or shoulder joint in the U.S. are made from —o r contain metal, because of its durability and the fact that it can stay intact inside the body without corroding. Chromium, nickel, cobalt, titanium and molybdenum are among the most common metals found in implants. Often, a prosthetic joint will contain more than one of these metal types. A very small number of Americans are allergic to one or more metals, with nickel allergy as the most common metal sensitivity.
What’s less clear is how often allergic reactions cause problems for people with metal joint implants. Studies have shown that in some people with a metal allergy, the metal in the implant triggers an immune reaction when it comes into contact with body fluids. When the circulating blood containing traces of the metal reaches the skin, it causes an irritation centered around the implant site, possibly swelling, a rash or blister.
The reaction can be systemic, a delayed response to the metal caused by specialized immune cells called T cells. The evidence about body-wide symptoms has been mainly anecdotal. There have been reports of a Georgia woman who had systemic symptoms due to a metal contact allergy after knee replacement surgery, as well as of an artist who developed body-wide symptoms after a double knee replacement and a Denver woman who reacted to a metal hip implant.
Symptoms of a body-wide (systemic) reaction that have been reported in these types of cases include pain or loss of function in the implant area, weakness or fatigue, diarrhea and headaches.