The anterior and posterior fat pads may be seen on a lateral radiograph of the elbow joint. Normally the anterior fat pad is visible as a relatively linear lucency in contact with the anterior aspect of the distal humerus. The posterior fat pad is not normally visible as it is hidden deep within the olecranon fossa.

2. Pathology

Distension of the elbow joint as occurs in effusion, haemarthrosis or synovitis will cause these fat pads to be displaced away from the humerus resulting in radiographic visualization of the posterior fat pad and antero-superior elevation of the anterior fat pad which adopts a curvilinear configuration (Fig.1). In the context of acute trauma this elbow fat pad sign is very suggestive of haemarthrosis secondary to an intra-articular fracture which in a child is most commonly a supracondylar fracture. See effusion