Metal Allergy discussion, Totally Hip, April 2001

From Bill M;

Your note got me to wondering about exactly what alloy is used these things. I had assumed that Cobalt Chrome referred to stainless steel alloys of iron, cobalt, and chrome. Turns out that is not the case. The alloy used by Osteonics (and I would guess most everyone else) is called "Vitallium" and was developed over 60 years ago for dentures. The composition is 5-7% Molydenum, 28-32% Chrome, and the balance Cobalt. It has a very long track record as dentures and ortho devices so I think allergy questions have been well addressed particularly since one of the reasons for using it all this time has been to avoid nickel allergies.

From Keith;

Nickel is commonly used in alloys with titanium. I believe it is also used in stainless steel (e.g., for some bone screws and plates). Titanium alloy is soft so it is not used in articulating surfaces but it is used in femur stems. I wasn't sure if it was present in trace amounts in orthopedic cobalt-chromes. I'll take your word that it is not.

From Tom;

Hi, I'm no metallurgist but i think that chrome-cobalt steel is made with nickel in the chrome part. Nickel is a very common allegen for some. The elisa-act blood test will show any allergy. The RAST or scratch tests the allergists do will not be conclusive.
Good luck.

From Enid;

There was a discussion a few months ago about people with metal allergies possibly having a problem with the metal/metal implants--unfortunately, I didn't save all the responses. I have problems wearing certain kinds of jewelry, especially earrings. Nickel is probably the culprit. Now at the suggestion of my OS, I have an appointment with an allergist who needs to know all the metals that may be contained in the various components. My surgeon's nurse told me that they use the DePuy system and that the stem is titanium and the Ball is cobalt/chrome. I believe there may be small amounts of other metals such as nickel in the implants, but I'm having a hard time getting the specifics from the customer service folks at DePuy.

From SJHimel:

WHAT IF I HAVE A METAL ALLERGY?

Contact allergies to certain metals are fairly common, particularly an allergy to nickel which is often found in costume jewelry. Vanadium, found in many titanium alloys, may also be a culprit. Symptoms include skin reddening, itching, and a rash. The problem is that most surgical implants are alloys which may include these metals, as well as others that produce
allergic responses. Manufacturers may even warn that their implants are not suitable for people with allergies; in that case, what do you do?

Unfortunately, there is no blood-test (RAS) method for detecting metal allergies; generally, allergists suggest that you acquire samples of the implant metal and keep them taped to the skin surface in the same location (such as the inside upper arm, where the skin is thin and sensitive) constantly for at least 7 to 10 days -- unless you develop a skin reaction earlier. The presumption is that if you don't react to the metal dermally you won't react internally. In fact, it appears that there may be no close relationship between skin response and systemic response anyway, skin being far more reactive than internal tissues. Nevertheless, if you do react to the sample you may want to consider a different implant; at the very least you should consult an allergy specialist.

The important lesson is to call ANY allergy you have to the surgeon's attention, particularly if it involves an implant you'll be wearing internally for a good long time. If you want to try this version of "patch testing" you must use one or more samples from all the surfaces of the specific implant you and your surgeon plan to use. The samples come in disc form (usually less than dime-size) from the implant manufacturer and can usually be obtained only on a loan basis by your surgeon; they are extremely expensive (the several-thousand-dollar range), so be careful not to lose any. Be sure to use hypoallergenic tape, since you don't want to confuse the skin reaction picture. Be prepared to wear the samples onstantly for up to two weeks, depending on the doctor and his caution level. Naturally, if you react early remove the samples and notify your surgeon.