Can I be Allergic to a Metal Implant?

Metallic implants are used in a wide variety of orthopedic surgical applications, including fracture repair and joint replacement surgery.  Some people are concerned about developing an allergic reaction to metallic implants. Is this possible, and can it be a cause of pain or irritation after surgery?

Answer: Hypersensitivity or allergic reactions can occur after contact with various metals. Most people are aware of skin sensitivity to metals, and whether this is related to problems with metal implanted inside the body is not well understood.

Metals Implanted into the Body:

The most common 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. Orthopedic implant alloys include nickel, aluminum, and others. Many people have known skin sensitivities to various metals. The most frequent sensitivity encountered is to lower quality 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 contract skin irritation from this metal.

Should I be Concerned About Metal Allergy When Getting an Implant?

It is possible that metal sensitivities are the cause of implant problems in some situations, but this is considered to be very 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 cause  of metal implant sensitivity and allergy are not well defined. Having a skin sensitivity to a particular metal is not thought to be necessarily correlated 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.

What if I Have a Skin Sensitivity to Nickel?

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 allergy. 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.

Is the OrthoTin TMJ System a Good Option for a Patient With a Sensitivity to Nickel?

OrthoTiN TMJ Implants are made from Titanium Alloy. Titanium has many desirable characteristics;  it is considered to be more biocompatible, has closer mechanical properties to that of bone than cobalt-chromium alloys used in other TMJ systems. Titanium alloy is widely considered the material of choice for orthopedic implants. Unfortunately, titanium is much less abrasion resistant in comparison to Co-Cr. To improve the hardness, and enhance biocompatibility of the titanium implants, the OrthoTin mandibular ramus component is coated with a titanium nitride coating. This coating results in an increased lubricity, improved durability, abrasion resistance, as well as improved hardness. A reduction in component wear leads to a reduction in metal ion release - reduced Nickel exposure. Studies demonstrate that Titanium Nitride coating reduces wear on UHMWPe by two thirds when compared to a cobalt-chromium alloy. In addition, the wear rates associated with a TiN Coat / UHMWPe interface are very minimal. The low wear rates, biocompatibility, and desirable mechanical properties of TiN coated titanium alloy devices show promise for the potential longevity of the OrthoTiN TMJ System.