Lipohemarthrosis (left) with fracture of lateral tibial plateau (right). Lipohemarthrosis is the mixture of fat and blood in a joint cavity following trauma. Specifically, intraarticular fractures can lead to migration of fat and blood from the marrow cavity into the joint space. Due to the fact that fat is less dense than blood, a fat-blood interface forms and can be seen on radiography as a fat-fluid level.