A reaction to a knee replacement can appear months or even years after the initial surgery.
Knee replacement metal allergies and sensitivities are more common with older, metal-on-metal joints.
People with known metal allergies or sensitivities should tell their surgeon prior toknee replacementsurgery.
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This article discusses knee replacement metal allergies and sensitivities.
It explores the causes and symptoms of a reaction and what to do if you suspect one.
Using skin patch tests and blood work, researchers identified metal sensitivity in nearly one-third of the study participants.
Metal Allergy vs.
Sensitivity
Metal allergyandmetal sensitivityare often used interchangeably in everyday conversations.
Throughout this article, we do the same.
However, while both are in the “allergy family,” there is an important difference worth clarifying.
Most reactions to knee replacements are hypersensitive reactions.
Instead, metal hypersensitivities typically present as contact dermatitis.
This can cause mild to significant local discomfort.
Metal hypersensitivity can begin at any time, even if you have never had a reaction before.
The immune response associated with sensitization occurs from prolonged exposure.
Metal allergies and sensitivities can be assessed using skin patch testing.
A blood test known as a nickel lymphocyte proliferation test is used to identify nickel sensitivity.
People with suspected metal allergies or sensitivities should undergo testing prior to knee replacement surgery.
However, pre-surgical allergy testing cannot completely rule out a potential reaction.
Why Is a Reaction to Knee Replacement Delayed?
Metal sensitivity is not an uncommon condition.
With prosthetic knees, stainless steel used to build the appliance contains around 10% nickel.
Metal allergies are referred to as delayed-key in hypersensitivity (DHT).
The delayed hypersensitivity occurs due to the natural corrosion of metals over time.
Any metal that comes into contact with body tissues will corrode to some degree.
This corrosion causes the formation of metal ions that ultimately trigger the inflammatory immune response.
So, skin testing for nickel, cobalt, and chromium hypersensitivity has limited value in diagnosing DHT.
Treatment Options
The challenge with metal hypersensitivity is that the diagnosis is not always 100% certain.
It requires a case-by-case evaluation weighing the potential benefits and risks.
The use of these implants is considered experimental and should be done with extreme caution.
With that said, some studies suggest that they may be beneficial for certain groups.
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