What is the most likely explanation for a young child refusing to move an arm after being pulled by it?

The most likely explanation for a young child refusing to move an arm after being pulled by it is subluxation of the radial head, often referred to as "nursemaid's elbow." This condition commonly occurs in young children (typically under the age of 5) when a sudden pull on the arm causes the annular ligament to slip over the head of the radius, resulting in a partial dislocation.

As a result of this injury, the child experiences immediate pain and may refuse to move the affected arm due to discomfort. The natural response to pain in children often involves guarding the injured limb, leading to the refusal to use the arm.

Subluxation of the radial head is particularly likely in this scenario because it typically occurs in the context of a gentle pulling motion, such as when a parent or guardian lifts a child by the arms. Unlike dislocation, which may involve a more severe trauma and often requires more significant force, subluxation is usually a result of minimal trauma.

Other potential explanations such as a shoulder dislocation, fracture, or septic arthritis would typically present with different signs or require different mechanisms of injury. Shoulder dislocation is less common in young children and would likely be more evident if accompanied by visible injury or significant