Radiology Cases Fat-fluid level LSBU

Description: Lipohaemarthrosis.
Active bone marrow in the mature skeleton is predomiantly localized to axial skeleton, including pelvis. The medulla limb bones contain mostly fat. This fat is liquid at body temperature and may be liberated from the bone by trauma. Where there is blood and/or joint-effusion and free-fat, the particular bounded tissue space may show a line of separation. In such a situation the usual rule applies, oil and water don't mix. A horizontal X-ray will detect the boundary. In lower limb trauma the lateral view is necessarily a lateral "shoot-through".