In a child presenting with a posterior fat pad sign, what type of injury is most likely responsible for their pain?

• A. Distal radial buckle fracture
• B. Nursemaid's elbow
• C. Supracondylar fracture
• D. Elbow dislocation

Answer: (C)

In the context of a child presenting with a posterior fat pad sign, the most likely injury responsible for their pain is a supracondylar fracture. The posterior fat pad sign is an important radiological indicator typically seen on lateral elbow X-rays, suggesting an underlying injury, particularly in pediatric populations.

When a supracondylar fracture occurs, it disrupts the normal positioning and integrity of the elbow joint, leading to the accumulation of fluid and resulting in the visibility of the posterior fat pad on imaging. This sign indicates that there may be joint effusion due to trauma, reinforcing the presence of a significant injury at the elbow.

Other types of injuries, like a distal radial buckle fracture, while common in children, typically do not present with a posterior fat pad sign since they are usually confined to the wrist area. Nursemaid's elbow, which involves the subluxation of the radial head, and elbow dislocation can cause pain and dysfunction but do not always produce the posterior fat pad sign. Therefore, given the specific indication of the posterior fat pad sign accompanying the child's symptoms, a supracondylar fracture is the most accurate interpretation of the injury responsible for their pain.