CAMRT Radiography Practice Exam

What is the indication of a positive fat pad sign?

1. Visible foreign body in the joint

2. Occult fracture not directly visible

3. Joint effusion without fracture

4. Normal range of motion

The correct answer is: Occult fracture not directly visible

A positive fat pad sign is typically indicative of an occult fracture that may not be directly visible on the radiograph. This sign occurs when there is an increase in joint effusion or hematoma, which displaces the fat pads around the joint. In patients, particularly with elbow injuries, the anterior and posterior fat pads may become elevated and visible on imaging, indicating underlying trauma such as a fracture—often of the radial head in the case of elbow injuries—despite the fracture itself not being clearly seen on the X-ray. While the presence of a visible foreign body in the joint could suggest injury, it does not correlate with the fat pad sign. Similarly, joint effusion could occur without an underlying fracture, and a normal range of motion would not signify any injury or trauma consistent with the presence of a fat pad sign. Thus, the positive fat pad sign is primarily associated with occult fractures, making it a crucial radiographic finding for assessment in clinical practice.