Joint replacement success may hinge on metal allergies for some people
Metal allergies can lead to failure of replacement joints so people should be evaluated for a possible reaction before and after surgery, according to a new review of research published in the Annals of Allergy, Asthma & Immunology.
Although metal allergies are relatively uncommon and most people have successful and stable joint replacements, the number of total joint replacements is on the rise and so is the number of revisions.
Metals used in joint replacements include cobalt, chromium, molybdenum, tungsten, manganese, titanium, aluminium, vanadium and nickel. But according to a study in Chemical Research in Toxicology, up to 17% of women and 3% of men are allergic to nickel.
“We think patients and doctors should be aware of hypersensitivity or allergy reactions to implanted joints and to monitor for signs and symptoms,” suggests Dr Michelle Pinson, who is involved in the work. “For some patients, an allergic reaction to metal in a joint can be very serious, however many reactions are mild and not too serious.”
When an allergy occurs, if it is minor it is dealt with via drugs, physiotherapy or steroid injections. But if the joint swells or loosens, it may need to be replaced with different components, avoiding the problematic metal.
The experts involved in the current review or research explain that it is still not clear whether metal joints increase sensitivity to metal, or if existing metal sensitivity leads to more joint failure after implantation. They suggest that people with a history of metal sensitivity should be tested before surgery, and anyone who experiences new joint pain, rash or hives after surgery should be considered for an allergy patch test.
But Dr Jared Foran, an expert not involved in the study, says it is not clear what a positive result on a skin or blood metal allergy test actually means.
“There are literally millions of patients that have metal plates or screws in their bodies from other types of orthopaedic work, such as fracture care, etc, yet we rarely diagnose metal hypersensitivity in these patients,” he explains .“There are plenty of patients that will test positive for metal allergy, but be perfectly happy with their joint implant. There are many more that will be unhappy with their implant, but test negative for allergy.”
More research is needed in the area.
“The real question is what do we do with the patients that have a poorly functioning total knee or hip and a positive allergy test, with no other clear explanation of why they hurt,” Dr Foran highlights. “We simply do not have the data in 2014 to make a real strong assessment of the best course of action for those patients.”
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