Workup of Patients with Suspected Metal Hypersensitivity

Hypersensitivity to metals (HtM) is still a matter of controversy in orthopedics and traumatology, while it is well known and established in other medical fields [1–3]. Over the last decades, several reports showed a correlation with clinical signs and the presence of metal devices or implants in joints of patients complaining pain, itching, swelling, bone resorption, and even skin necrosis [4, 5]. Unfortunately, in many cases of unexplained painful joint after application of a metal device, a potential HtM has been demonstrated only indirectly: after their removal or substitution with anallergic devices, patients returned fully or nearly asymptomatic [3, 6–8]. Nickel is the metal ion responsible of a percentage up to 15% of contact dermatitis in the general population, as well as the most involved ion in the HtM in patients with painful prosthesis, mostly made of alloys containing nickel [1, 4–11]. Based on such a high incidence of nickel-induced contact dermatitis, an accurate medical history should always be performed in candidates for a joint replacement, particularly in allergic subjects or workers at risk of sensitivity to various substances containing nickel (painters, cleaners) [4, 12]. On the other hand, HtM should be considered as a potential cause of painful implants after excluding the most common causes of failure or pain after surgery [12, 13].