Hemarthrosis

Haemarthosis is haemorrhage into a joint space and can be regarded as a subtype of a joint effusion.

Trauma is by far the most common cause of a haemarthosis. Other causes include bleeding disorders, neurological deficits, arthritis, tumours and vascular damage.

Lipohaemarthrosis is a result of an intra-articular fracture with mixing of fat and blood from bone marrow.

Radiographic features

There is a wide overlap in the radiographic features of a haemarthosis and joint effusions of other aetiologies.

Radiography

Haemarthosis displaces normal structures, for example in an elbow, anterior and posterior fat pads may be elevated or visible respectively. In the knee, there may be anterior displacement of the patella and quadriceps tendon. In the shoulder, the humerus may be inferiorly displaced, mimicking a dislocation.

Ultrasound

Ultrasound of a haemarthrosis may appear as a joint effusion with or without internal echoes depending on age of the haemorrhage, and with layering of cells (haematocrit effect).

Management

Management consists of removal of the underlying cause, e.g. correction of coagulation. Aspiration of haemarthrosis following trauma is controversial as needle insertion technically converts a closed fracture to an open one with increased infection risk.