Cutaneous Metal Hypersensitivity Reaction.

A 53-year-old lady underwent a left total knee arthroplasty. She developed a dermatitis over the left knee on postoperative day 5, which worsened over the next 2 weeks and spread to the trunk despite regular topical corticosteroids and oral antihistamines. Physical examination revealed an erythematous plaque over the left knee and urticated plaques over the neck. She was given a course of oral and topical corticosteroids with resolution. Subsequent patch testing showed a showing ++ reactions to gold and nickel, and + reactions to copper, palladium, rhodium, titanium, vanadium, zinc, and hydroquinone. Orthopedic implants contain metal alloys, which may include nickel, cobalt. Hypersensitivity to implants allergy may arise from the metal alloy or bone cement. Metal hypersensitivity reactions (MHR) can manifest as a local or systemic contact dermatitis weeks to months following exposure. The role of MHR in contributing to prosthesis failure is conflicting. In patients with no history of metal allergy, pre-implant patch testing is not routinely recommended as a positive patch test does not consistently predict in vivo metal-induced complication. MHR may be managed conservatively with good outcomes. However, in patients with MHR and implant failure, or in a preoperative patient with a proven and clinically relevant hypersensitivity, replacement of the implant, or implant with a titanium or oxidized zirconium alloy should be considered.