occult fracture

On an elbow X-ray, the fat pad sign, also known as the sail sign suggests an occult fracture.

MRI sensitivity for radiographically occult fracture is greater than CT.

A fat pad sign is an elevation of the anterior and posterior fat pads of the elbow joint, and suggests the presence of an occult fracture.

The main reason for radiographic examination is to exclude bony lesions such as occult fractures, slipped upper femoral epiphysis or bone tumours (such as osteoid osteoma).