A 4 year boy is complaining of pain around elbow with the hand held in pronation with extension. X ray of the elbow joint is normal. What is the most probable diagnosis?

Pulled elbow or Nursemaid elbow or Babysitter's elbow or radial head subluxation is most commonly occurs in children aged 1-4 years. The etiology is slippage of the head of the radius under the annular ligament. The distal attachment of the annular ligament covering the radial head is weaker in children than in adults, allowing it to be more easily torn. As children age, the annular ligament strengthens, making the condition less common. The oval shape of the proximal radius in cross-section contributes to this condition by offering a more acute angle posteriorly and laterally, with less resistance to slippage of the ligament when axial traction is applied to the extended and pronated forearm. The patient resists supination/pronation as well as flexion/extension of the forearm. Axial traction is the most common cause of nursemaid elbow. A fall is the second most common mechanism of injury. Infants have been repoed with nursemaid elbow after rolling over or being assisted to roll over. The Monteggia fracture is a fracture of the proximal third of the ulna with dislocation of the head of the radius.