A small child is holding their arm in pronation and cannot supinate it without pain. What is the likely diagnosis?

The scenario describes a small child who is holding their arm in pronation and is unable to supinate it without experiencing pain. This presentation is highly indicative of Nursemaid's elbow, which is a common injury in young children, typically resulting from a sudden pull on the arm.

In Nursemaid's elbow, also known as radial head subluxation, the radial head becomes partially dislocated as it is pulled away from its normal position in the elbow joint. This results in difficulty with forearm supination, coupled with pain and reluctance to move the affected arm. Children may often present with the arm held against their body in a pronated position, as this minimizes discomfort.

Other diagnoses, such as a fractured radius, could potentially present with similar arm positioning and pain; however, the mechanism of injury and age group typically involved would not align as closely with the classic presentation of Nursemaid's elbow. Osteomyelitis involves an infection of the bone that would usually present with systemic symptoms or localized signs of inflammation, which are not described here. Tendinitis, while it can cause pain and limit movement, is less likely in this age group and doesn't typically lead to a specific position like pronation.

Therefore, based on the child’s inability