Lipohemarthrosis of the knee: MR imaging

Two patients with sports-related knee injuries underwent magnetic resonance (MR) imaging, which demonstrated intracapsular fractures and effusions with a signal pattern characteristic of lipohemarthrosis. Four distinct signal bands were identified: superior band representing floating fat, a central band containing serum, an inferior band of dependent red blood cells, and a thin band representing chemical shift artifact at the interface of serum and floating fat.