Radial head subluxation (Nursemaid elbow)

A 3-year-old boy is brought to the clinic because of left elbow pain. Father of the patient says that after picking up the boy from day care, he noticed his son was not moving his elbow and complained of pain. Patient is holding his left elbow flexed and pronated. Physical examination shows tenderness over the lateral aspect of the left elbow joint on palpation. Which of the following is the most likely diagnosis?