Metallosis and Metal-Induced Synovitis Following Total Knee Arthroplasty: Review of Radiographic and CT Findings

Metallosis and metal-induced synovitis are well-recognized complications of metal-backed polyethylene joint prostheses and have been frequently described in the orthopedic surgery literature; however, relatively fewer articles discussing the radiologic aspects of this complication have been published. To illustrate the importance of radiologic findings in the diagnosis and management of these patients, we present a case of metallosis and metal-induced synovitis complicating two revisions of a total knee arthroplasty, caused by polyethylene liner wear and dissociation of the polyethylene liner from the metal-backed patellar prosthesis. Specific attention is given to reviewing signs that aid in diagnosis, such as the “bubble sign,” “cloud sign,” and “metal-line signs.