The importance of preventing infection in total knee arthroplasty (TKA), as well as effectively treating the infected arthroplasty, is readily apparent. Preventing infection after TKA involves recognizing the preoperative, intraoperative and postoperative variables that predispose to infection. Successful treatment of the infected TKA involves selection of the appropriate treatment modality. While acute infections may be eradicated by debridement alone, chronic infections will require prosthesis removal and further treatment (either reimplantation, or arthrodesis in a clean bed). Selection of the appropriate treatment is based on both clinical and radiographic considerations.