Penny for My Thoughts on Nickel Allergy Relating to Joint Replacements and Dental Implants

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Penny for My Thoughts on Nickel Allergy Relating to Joint Replacements and Dental Implants

How can ear/body piercings affect your joint replacement?

It happens almost weekly in my allergy clinic.  I get a referral from an orthopedic surgeon asking me to rule out allergy to nickel metal in a patient waiting for a hip or knee replacement.

An allergic reaction to nickel is one of the most common causes of an itchy skin rash. It can also cause other changes in the skin, such as redness and blistering. Allergic reactions to nickel are increasing in North America and Europe. The allergy may develop at any age, and is more common in women than men. It’s estimated that in the U.S. alone over 2.5 million adults and a quarter million children are allergic to nickel.

You may think, why should I worry about nickel? I’m young and won’t be getting a hip replacement anytime soon. While that may be the case, you don’t have to be ‘old’ to get a hip or knee replacement or a dental implant. Athletes, after years of wear and tear, can require them at a relatively young age, and if you’re in an accident that knocks out a few teeth, a dental implant may be what is required to keep you smiling.

Dental implants, for example, are often made from Nitinol, a metal composed of approximately 50% nickel. Heart stents, which keep blood vessels open for better blood flow, also use some component of nickel, as do hip and knee replacements.

Stainless steel is a steel alloy that may combine nickel, cobalt and chrome metals. Stainless steel is noted for its corrosion resistance, and it is widely used for food handling and cutlery among many other applications, including medical implants. Allergy to nickel develops when a  nickel containing metal  is in contact with the skin and is released from that metal.  This occurs in scenarios like body piercing via the metal post or when a metal object is in contact with the skin for long periods of time. In some individuals the immune system sees the nickel as something it wants to attack and once this happens you then are considered allergic.

How this allergic reaction manifests on the inside of a heart vessel or inside your hip joint is not really known by the medical community.  But, we do see failures of these prosthetics, as well as side effects. One theory is that patients who have become allergic to these metals from skin contact, may have poorer outcomes when they are implanted into the body.

The European Union Commission instituted a Nickel Directive in 1994

(http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A31994L0027) in an effort to decrease the rising incidence of allergic reactions to nickel. The Nickel Directive imposes limits on the amount of nickel that may be released from jewelry and other products intended to come into direct and prolonged contact with the skin. These limits, known as migration limits, are:

• 0.2 µg/cm2/week for post assemblies which are inserted into pierced ears and other pierced parts of the human body.

• 0.5 µg/cm2/week for other products intended to come into direct and prolonged contact with the skin.

• The Nickel Directive has added several amendments including 2009 for cellphones and 2014 for toys

It is known that nickel is slowly released when in contact with the body’s heat and sweat from a hard objects like an earring post or watch face.  If the amount of nickel released from this object can be controlled and kept to a low level, an allergic reaction can be prevented.  The Nickel Directive has resulted in the decrease in nickel allergies in some of the countries in the EU.

Unfortunately, in Canada and the US no such legislation exists. You may recall news reports about allergic reactions to cellphone and iPads over the past decade.  These reactions were from nickel released from the cellphone metal components touching the cheeks of users or from the iPads. Apple now follows the EU derivative guidelines for its metal components that touch the skin, as do other manufacturers but many don’t as this is not enforced legislation.

To make a definitive diagnosis of a nickel allergy an allergy skin test called ‘patch testing’ is required. This is typically done at a Dermatologist’s office.  A patch with nickel in a pre-determined concentration is applied to the skin and left for 48 hours then removed. A delayed reading of the skin is done in another 24 or 48 hours to see if a rash has developed at the site.  The problem with this test is it is not very predictive of what is happening inside a joint or heart vessel, but right now this is the best test we have to determine allergic reactions to materials that come into contact with our bodies, both on our skin and inside us.

The challenge is that an allergic reaction internally, e.g. your joint replacement or blood vessels, doesn’t always manifest itself the same way as it might on your skin.  Some patients allergic to nickel have implants with nickel and do well.  It’s important to note that if you are considering piercing your child’s ears, make sure the posts are nickel free. If you are already allergic and want to buy or use products that release less than 0.5ug/cm2 buy the Nickel stop test available on the internet. www.dormer.ca/dormercos/nickel.aspx.

From my perspective as a Dermatologist with an extensive background in determining allergies and allergic reactions in patients, a Nickel Directive, such as the one in Europe, is needed in the US and Canada because at this time there is no consensus on how to determine and treat potential metal allergy to prosthetics.

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