Causes / typical injury mechanism: The mechanism of injury for nursemaid's elbow is longitudinal traction of the arm. This is usually caused by a pulling force on the upper extremity, but it also can occur from twisting of the elbow or a fall on an outstretched arm. It commonly results from a strong tugging on a child's arm to prevent them from falling or from swinging the child playfully by the arms. This results in radial head subluxation, and the annular ligament becomes interposed between the radial head and capitellum, preventing relocation. The name "nursemaid's elbow" stems from the blame historically being placed on a child's caregiver.

Classic history and presentation: This acute injury results in immediate pain, which worsens with attempted movement. There is often a known cause and an audible popping sound at the time of injury, but it is also possible for the caregiver to be unaware of any particular injury event. Expect the child to be holding the affected arm in a protective elbow flexion manner and refusing to use or extend the elbow. The child may appear in distress or may present comfortably as long as the arm is immobilized.

Prevalence: Nursemaid's elbow is one of the most common upper-limb injuries in the pediatric population.

• Age – This diagnosis is most frequently seen between the ages of 1 and 4 years. It is rare in older children as the annular ligament strengthens over time and the radial head widens, increasing the stability.
• Sex / gender – There is a slight predominance in females.

Risk factors: Risk factors include abnormalities in the radial head and abnormalities in the annular ligament.