Secondary Infection of Adverse Local Tissue Reaction Leading to Amputation in a Patient With a Modular Knee Endoprosthesis.

Three years after endoprosthetic reconstruction of the proximal tibia, a patient presented with a skin ulceration near the surgical site. The knee was not clinically infected, but the patient had elevated serum cobalt levels. Dermatological evaluation diagnosed a friction ulcer. The ulcer failed to heal, and the patient underwent débridement and local flap advancement. Cultures grew Staphylococcus epidermidis, and they were treated with antibiotics. The ulceration recurred and repeated limb salvage was discussed, although eventually, the patient elected to undergo amputation. Pathology from the resected ulcer showed fibrinoid necrosis with aseptic lymphocytic vasculitis-associated lesion.