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Patch testing useful before orthopedic device implantation

Patch testing for metal hypersensitivity can be a helpful procedure before implanting orthopedic devices, according to recent results.

Researchers evaluated the patch test results of 72 patients with the potential for metal hypersensitivity from implanted devices. Patches were left on for 48 hours, with reactions evaluated on the second or third day and then again on the sixth or seventh day. The participants were divided into two groups: those who were tested before (n=31) and after (n=41) implantation. Evaluated factors included surgeons’ choice of metal implant alloy and hypersensitivity complications related to implants after surgery.

In the preimplantation group, 21 patients (68%) indicated at least one positive reaction to the patch test, with 15 showing more than one reaction. A clinical history of metal hypersensitivity was more likely in these 21 patients than those in the group that did not test positive (P=.03), and referring surgeons accounted for hypersensitivity when choosing an implant in all 21 cases.

Fewer positive test results were reported in the postimplantation group (15 patients, or 37%), and a clinical history of metal hypersensitivity was more common among patients with positive results (53%) than those with negative results (19%; P=.03). Common metals leading to positive test results included nickel, cobalt, palladium and chromium. Of the participants with positive results, 10 tested positive for at least one metal contained within their implant, and the six patients who had their devices removed experienced resolution of their symptoms, which included chronic pain at the implant site and dermatitis.

“The findings of this study support a role for patch testing in patients with a clinical history of metal hypersensitivity before prosthetic device implantation,” the researchers wrote. “The decision on whether to remove an implanted device after positive … results should be made on a case-by-case basis, as decided by the surgeon and patient.”