Allergy to Metal Orthopedic Implants

Metal implants are used in a variety of orthopedic surgical settings, including fracture repair and joint replacement surgery. Some people are concerned about developing an allergic reaction to the metal implants. Is this possible, and could it be a cause of pain or irritation after surgery?

Hypersensitivity or allergy can occur after contact with various metals. While these words "hypersensitivity" and "allergy" are often used interchangably, they are not really the same. That said, in the discussion of metal implants in the body, these words are often used in the same discussion. Most people are aware of skin sensitivity to metals, and whether or not this is related to problems with metal implanted inside the body is not well understood. Most people have experienced some type of skin sensitivity to jewelry to watches, as some metals can cause irritation to the skin, and some people may be more prone to developing a response to various metals. 

The most commonly implanted metals used in orthopedic implants are cobalt/chrome, stainless steel, and titanium. All orthopedic implants are alloys, meaning they have several different metals in the implant. The base metal(s) are found in the highest quantities, but smaller amounts of other metals are also found in the implant. Metals often included in orthopedic implant alloys include nickel, aluminum, and others.

Many people have known skin sensitivities to various metals. The most frequent sensitivity encountered is to inexpensive jewelry that may contain nickel. Some orthopedic implants contain small amounts of nickel, and there has been concern that this may be an issue for those individuals receiving implants who also have skin irritation from this metal.

Metal sensitivities and allergies have been implicated in some situations of painful or problematic orthopedic implants. It is likely that metal sensitivities are the cause of implant problems in some situations, but this is also thought to be extremely rare. Pain around the site of orthopedic implants has many causes, and before blame can be assigned to metal sensitivity or allergy, a thorough investigation must occur.

Unfortunately, the symptoms of metal implant sensitivity and allergy are not well defined. Having a skin sensitivity to a particular metal is not thought to correlate well to having sensitivities to implanted metals. Therefore, making the diagnosis of a sensitivity or allergy to metal implants usually requires the removal of the implant. Patients who have pain around metal implants and associated skin changes (eczema) should be evaluated for possible metal sensitivity.

As many as 10% to 15% of the general population has a sensitivity or allergy to nickel. Patients who are sensitive to nickel should inform their doctors of this reaction. Your doctor may want to consider the use of an implant made without nickel in the alloy (usually a titanium implant). This may not always be possible, and an implant made with nickel may be the most appropriate implant available for your condition. Fortunately, the chance of developing problems with metal implants, even in people with known skin sensitivities, is extremely low.

Removal of metal implants for treatment of an allergy or sensitivity to metal is rarely performed. While it is nice to know that metal implants rarely cause allergic reactions that require implant removal, it has been reported, and some individuals have found resolution of their symptoms after removal or replacement of their implants. Your doctor can help you determine the cause of your problems and the appropriate treatment to consider. Fortunately, for those patients who truly have metal sensitivity causing their implant problems, removal of the implant will often provide immediate relief of symptoms.

There are implants made of nonmetal materials. Unfortunately, there is very limited data about the effectiveness and longevity of these non-metal implants. Most of these alternative implants are made of ceramics, and how well these implants will last is not well known because so few are in use. Therefore, these materials should only be used in the very specific circumstance where metal needs to be removed, or if there is a high likelihood of a particular individual having problems with a metal implant.