Fat Pad Sign of the Elbow

MANUAL MINORS

The fat pad sign of the elbow refers to the visibility of the anterior or posterior fat pads on a lateral X-ray of the elbow, indicating joint effusion or haemarthrosis. This finding suggests an intra-articular injury, commonly associated with occult fractures, such as supracondylar fractures in children or radial head fractures in adults.

Diagnosis

Diagnosis of the fat pad sign is made through a lateral elbow X-ray. Normally, the anterior fat pad may be visible if displaced, but the presence of the posterior fat pad is always abnormal and is associated with haemarthrosis and intra-articular fracture. Even if a fracture is not visible on the X-ray, the posterior fat pad finding strongly suggests the presence of an occult bone injury.

Differential Diagnosis

Condition	Characteristics
Supracondylar fracture	Common in children, may not be visible on the initial X-ray.
Radial head fracture	Common in adults, with localised pain over the radial head.
Ligamentous injury	Displacement of fat pads without visible fracture, with pain and instability.
Traumatic synovitis	Inflammation of the synovial membrane following minor trauma.
Idiopathic haemarthrosis	Blood accumulation in the joint without apparent fracture.

Emergency Management

In the presence of a visible fat pad sign, emergency management includes immobilising the elbow with a splint to prevent movement and reduce pain. Analgesics and non-steroidal anti-inflammatory drugs (NSAIDs) are prescribed, and additional imaging studies, such as a CT or MRI, may be recommended if a fracture is not evident on the X-ray. If significant haemarthrosis is suspected, arthrocentesis may be necessary.

Definitive Treatment

Definitive treatment depends on the underlying diagnosis. If a fracture is confirmed, reduction, immobilisation, or surgery may be required based on the severity. Ligamentous injuries or synovitis can be managed with rest, physiotherapy, and analgesics. In cases of occult fractures, additional imaging and potential surgical intervention may be needed depending on fracture stability.