On a normal lateral elbow image, the anterior fat pad of the humerus is closely adjacent to the humerus and the posterior fat pad is pressed into the hawk’s nest by the triceps muscle, so it cannot be visualized on the lateral elbow radiograph. When an injury occurs to the elbow, fluid or bleeding accumulates in the joint, the joint capsule swells, and the anterior or/and posterior fat pads are visualized on the photograph, it is called a positive fat pad sign. When the fat pad sign is positive, it is important to read the film carefully to rule out the possibility of a fracture. In the x-ray sign of elbow injury, if there is swelling of the joint, positive fat pad sign; orthopantomorphic image with angular, wrinkled or small wave-like changes in the bone cortex; lateral image with “x”-shaped cortical fracture of the condyle with angular and localized disorganized trabecular structures, etc., the fat pad sign of minor fracture of the condyle should be considered. It is also called Sailing sign, indirect fracture sign of elbow joint (dilmann), and figure-of-eight sign. It refers to the anterior and posterior fat pad displacement to confirm the intra-articular capsule oozing, suggesting the accumulation of blood and fluid in the elbow joint; although the fracture line is not visible in the elbow x-ray, the presence of the anterior fat pad sign strongly suggests a fracture of the radial tuberosity. The translucent area pointed out by the arrow is the fat pad image. Due to the bleeding in the joint capsule, the synovial membrane and fat pad are pushed, and the “sail”-like or “eight”-like image appears on the lateral film.