A 57-Year-Old Woman with Knee Pain, Lipohemarthrosis of the Knee
Lipohemarthrosis of the Knee 1. Definition Lipohemarthrosis refers to the presence of both fat and blood within a joint space , most commonly seen in the knee joint , typically following intra-articular fractures . The fat originates from bone marrow, while the blood results from vascular injury associated with the fracture. 2. Cause and Etiology Primary cause: Intra-articular fracture of a bone containing marrow fat , usually: Distal femur Proximal tibia Patella Mechanism: A fracture extends into the joint space. Marrow elements (including fat) and blood leak into the synovial cavity. The fat separates from the blood due to differences in density and buoyancy . Common etiologic events: Trauma (e.g., falls, motor vehicle accidents, sports injuries) Rarely, non-traumatic causes such as: Pathological fractures (e.g., due to bone tumors or osteomyelitis) 3. Pathophysiology...