Lipid laden macrophages in synovial fluid: a late finding in traumatic arthritis

A 66-year-old man presented with arthritis of the right knee of 3 months' duration. Cytologic examination of synovial fluid (SF) showed numerous lipid laden macrophages. Radiographs and a nuclear scintigram established the presence of a fracture of the lateral tibial plateau. The diagnostic significance of lipid laden macrophages in SF is reviewed.