Allergic Sensitization to Nickel and Implanted Metal Devices: A Perspective

There is continuing interest in the interrelationships between allergic sensitization to metal allergens, metal implants, and the development of adverse reactions to implanted devices. Here, we focus on sensitization to nickel (although, in practice, it is commonly not possible to distinguish between events associated with nickel and other potentially allergenic metals used in devices). The purpose of this article was to review whether exposure to nickel resulting from implanted devices is associated with the development of de novo sensitization to nickel and also whether nickel sensitization, either newly acquired or pre-existing, has a causal relationship with adverse health effects. In addressing these issues, a variety of devices, including metal-on-metal hip implants, cardiac and endovascular stents and filters, and the gynecologic implant Essure, are considered. Also addressed is the question of whether pre-operative assessment of nickel allergy (and allergy to other implant metals) is required. The conclusions reached are that (a) sensitization can potentially be acquired as the result of exposure to implants containing nickel, but is not a common occurrence; (b) sensitization to nickel and/or other metal allergens is very rarely a cause of adverse reactions to implants; and (c) routine preoperative patch testing for sensitization to nickel is unnecessary, unless there is a significant clinical history of nickel allergy.