Sail sign
Encyclopedia
On an elbow X-ray
the sail sign suggests an occult
fracture. Its name derives from the fact that, with some imagination, it has the shape of a spinnaker (sail)
. It rises from displacement of the fat pad
around the elbow joint. Both anterior and posterior sail signs exist and both can be found on the same X-ray.
In children, a sail sign suggests a supracondylar fracture
of the humerus
. In adults it suggests a radial head
fracture.
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
the sail sign suggests an occult
Occult
The word occult comes from the Latin word occultus , referring to "knowledge of the hidden". In the medical sense it is used to refer to a structure or process that is hidden, e.g...
fracture. Its name derives from the fact that, with some imagination, it has the shape of a spinnaker (sail)
Spinnaker
A spinnaker is a special type of sail that is designed specifically for sailing off the wind from a reaching course to a downwind, i.e. with the wind 90°–180° off the bow. The spinnaker fills with wind and balloons out in front of the boat when it is deployed, called flying. It is constructed of...
. It rises from displacement of the fat pad
Fat pad
A fat pad is a mass of closely packed fat cells surrounded by fibrous tissue septa. They may be extensively supplied with capillaries and nerve endings.Examples are:* Intraarticular fat pads. These are also covered by a layer of synovial cells...
around the elbow joint. Both anterior and posterior sail signs exist and both can be found on the same X-ray.
In children, a sail sign suggests a supracondylar fracture
Supracondylar fracture
A supracondylar fracture is a fracture, usually of the distal humerus just above the epicondyles, although it may occur elsewhere. While relatively rare in adults it is one of the most common fractures to occur in children and is often associated with the development of serious...
of the humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
. In adults it suggests a radial head
Radius (bone)
The radius is one of the two large bones of the forearm, the other being the ulna. It extends from the lateral side of the elbow to the thumb side of the wrist and runs parallel to the ulna, which exceeds it in length and size. It is a long bone, prism-shaped and slightly curved longitudinally...
fracture.