title: Severe metallosis following total knee arthroplasty: a case report and review of radiographic signs.
abstract: Metallosis is an uncommon complication following total knee arthroplasty that leads to osteolysis and implant loosening due to chronic inflammatory reaction. Abrasion between the metallic surfaces of the implant releases metallic debris that interacts with the periprosthetic soft tissues and causes chronic synovitis. Here we present a case of a 65-year-old man who had undergone total knee arthroplasty 10 years ago and developed implant loosening associated with severe metallosis and varus instability. Radiographs show the three typical signs of metallosis: metal-line sign, bubble sign, and cloud sign. This patient was subjected to revision surgery consisting of debridement and primary implant replacement by a hinged endoprosthesis. Knowledge of the typical radiographic and clinical findings of metallosis is important to rapidly diagnose this complication and avoid progressive joint destruction.
authors.affiliation: Institute of Orthopaedics and Traumatology, Faculty of Medicine, University of São Paulo, Sao Paulo, Sao Paulo, Brazil.
authors.forename: Camilo Partezani
authors.initials: CP
authors.lastname: Helito
authors.forename: Carlos Vinícius
authors.initials: CV
authors.lastname: Buarque de Gusmão
authors.forename: Fabio Janson
authors.initials: FJ
authors.lastname: Angelini
authors.forename: Luis Eduardo Passarelli
authors.initials: LE
authors.lastname: Tirico
authors.forename: José Ricardo
authors.initials: JR
authors.lastname: Pécora
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D003937:Diagnosis, Differential; D005500:Follow-Up Studies; D000075322:Heavy Metal Poisoning; D006801:Humans; D007592:Joint Diseases / Q000150:complications / Q000000981:diagnostic imaging* / Q000601:surgery; D008297:Male; D011041:Poisoning / Q000209:etiology* / Q000601:surgery; D011183:Postoperative Complications / Q000000981:diagnostic imaging* / Q000601:surgery; D011475:Prosthesis Failure / Q000009:adverse effects*; D011859:Radiography; D012086:Reoperation; D013585:Synovitis / Q000150:complications / Q000000981:diagnostic imaging* / Q000601:surgery; D016896:Treatment Outcome