A case of intra-articular fracture of the knee joint with three layers within lipohemarthrosis by ultrasonography and computed tomography.

We report a case of intra-articular fracture of the knee joint showing three layers within lipohemarthrosis. Sagittal ultrasonography showed three layers (double fluid-fluid level): a superior hyperechoic layer of fat, an intermediate anechoic layer of serum, and an inferior hypoechoic layer of red blood cells. Horizontal computed tomography imaging demonstrated the same three layers. This is the first case of lipohemarthrosis in which three layers of joint effusion were confirmed by both ultrasonography and computed tomography.