Radiographic evaluation of periprosthetic metallosis after total knee arthroplasty

This retrospective study examined the clinical significance of a radiographic sign associated with periprosthetic metallosis after total knee arthroplasty. Of 71 knees undergoing revision arthroplasty over an 8-year period, 11 had gross evidence of metal debris identified intraoperatively. Histologic preparations confirmed the presence of particulate metal debris in all cases. Radiographs in 7 of 11 cases were positive for metallosis. The radiographic sign identified on lateral radiographs was divided into 3 types based on the size of the mass. The magnitude of soft tissue pathology and the extent of osteolysis correlated with the size of the mass on preoperative radiographs. Replacement of all components was necessary in 71% of cases with radiographs positive for metallosis and 47% of cases with negative radiographs. Only 1 of the 11 knees with metallosis had a late postoperative infection, for which 2-stage revision arthroplasty was required. All cases with positive radiographs had gross and histologic confirmation of metal and polyethylene debris. These data suggest that careful assessment of radiographs can facilitate preoperative planning.