What is the most likely diagnosis for a 5-year-old child who fell off a bike and has posterior displacement of the distal aspect of the humerus?

• A. Extension-type supracondylar humeral fracture
• B. Radial head fracture
• C. Medial epicondyle fracture
• D. Distal humeral fracture

Answer: (A)

The most likely diagnosis is an extension-type supracondylar humeral fracture. This type of fracture is common in children, particularly between the ages of 2 and 7, and typically occurs as a result of falling onto an outstretched hand. The mechanism of injury, combined with the posterior displacement of the distal aspect of the humerus observed in this scenario, aligns well with the characteristics of an extension-type supracondylar fracture.

In this injury, the distal fragment in a supracondylar fracture often becomes displaced in a posterior direction due to the mechanism of injury and the anatomical dynamics of the elbow joint during such falls. Recognizing these patterns is crucial for proper diagnosis and subsequent management of these types of fractures in the pediatric population.

Other conditions, while they may occur in children, do not fit the specific mechanics and presentation as well as the supracondylar humeral fracture does in this instance. Radial head fractures, for example, are less common in this age group and typically result from different mechanisms of injury. Medial epicondyle fractures might also occur due to elbow loading, but they would not typically present with posterior displacement of the distal humerus. Distal humeral fractures are less specific