Radial Head Subluxation (aka, "Nursemaid's Elbow")

Radial head subluxation (aka, "nursemaid's elbow" or "pulled elbow") refers to annular ligament displacement over the radial head and into the radiohumeral joint. In children < 5 five years old, the annular ligament is too weak to withstand sudden traction on the radius. So, if the arm is straight (elbow extended) and pronated, and the distal arm is pulled, then the annular ligament slips over the head of the radius and is displaced into the radiohumeral joint. Think of a caretaker (a "nursemaid"), suddenly grabbing the wrist of a child who is pulling away. The caretaker typically becomes aware there is an issue because the child stops using the affected arm and holds it close to the body in partial elbow flexion and pronation. Clinical evaluation (history and physical) is sufficient to make the diagnosis. Radiographs are unnecessary. Assess for bone fracture if any of the following are true (or if anything about the presentation does not fit):

• Signs of bony inflammation or tenderness to palpation.
• If the child is > 5 years-old.
• The annular ligament should be strong enough to withstand traction in children > 5 years-old.
• Pain is uncommon in RHS and should raise concern.

Radial head reduction is typically done via hyperpronation reduction. It’s quick (but painful) and can be done in the office (or urgent care) and does not require emergency room assessment or imaging (unless any of the red flag features above are present).