9.17 Subluxation of the Head of the Radius 
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(Nursemaid's Elbow)
agk's Library of Common Simple Emergencies

Presentation
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A toddler has received a sudden jerk on his arm 
causing enough pain that he holds it motion- 
less. Circumstances surrounding the injury may 
be obvious (such as a parent pulling the child 
up out of a puddle); or obscure (the babysitter 
who reports that the child "just fell down"). 
The patient and family may not be accurate 
about localizing the injury, and think that the 
child has injured his shoulder or wrist. The 
patient is comfortable at rest, splinting his 
arm with mild flexion at the elbow and pro- 
nation of the forearm. There should be no 
deformity, crepitation, swelling, or discolor- 
ation of the arm. There is also no palpable 
tenderness except over the radiohumeral joint; 
the child will start to cry with any movement 
of the elbow.

What to do:
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- Rule out any history of significant trauma, 
    such as a fall from a height.
- Thoroughly examine the entire extremity, 
    including the shoulder girdle, hand and 
    wrist.
- If there is any suspicion of a fracture, get 
    an x-ray. 
- When subluxation is suspected, place the 
    patient in the parent's lap and inform the 
    mother or father that it appears their 
    child's elbow is slightly out of place and 
    that you are going to put it back in. Warn 
    them that this is going to hurt for a few 
    moments.
- Put your thumb over the head of the radius 
    and press down while you smoothly and fully 
    extend the elbow, and at the same time 
    supinate the forearm. Complete the 
    procedure by fully flexing the elbow while 
    your thumb remains pressing against the 
    radial head and the forearm remains 
    supinated. At some point you should feel a 
    click beneath your thumb. The patient will 
    usually scream for a while at this point. 
    Leave for about ten minutes; then return 
    and re-examine to see that the child has 
    fully recovered. Post-reduction immobil- 
    ization is usually unnecessary.
- Reassure the parents, explain the mechanism 
    involved in the injury, and teach them how 
    to prevent and treat recurrences.
- Without full recovery, get x-rays. 
- If x-rays are negative, but the child still 
    does not use his arm normally, place the 
    arm in a sling and instruct the family to 
    seek orthopedic followup care if recovery 
    doesn't occur within 24 hours.

What not to do:
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- Do not attempt to reduce an elbow where the 
    possibility of fracture or dislocation 
    exists.
- Do not get unnecessary x rays when all the 
    findings are consistent with nursemaid's 
    elbow. The x-rays may appear normal even 
    when the radial head is indeed subluxed. 
    The dislocation is subtle, and requires 
    measurement or comparison to appreciate. 
    (Draw a line down the axis of the radius. 
    It should bisect the capitellum of the 
    lateral humerus.) Associated fractures 
    occur, yet are not common.
- Do not confuse nursemaid's elbow with the 
    more serious brachial plexus injury, which 
    occurs after much greater stress and 
    results in a flaccid paralysis of the arm.

Discussion
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This injury is an anterior subluxation of the 
radial head away from the capitellum through 
the annular ligament, and occurs almost 
exclusively among children between 18 months 
and 3 years of age. On occasion, if the 
subluxation has been present for several hours, 
edema, pain, and natural splinting will 
continue even after reduction, or may prevent 
reduction.

References:
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- Quan L, Marcuse EK: The epidemeology and 
    treatment of radial head subluxation. *Am J 
    Dis Child* 1985;139:1194-1197.
- Frumkin K: Nursemaid's elbow: a radiographic 
    demonstration. *Ann Emerg Med* 1985; 
    14:690-693.

Illustration
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img/cse0917.gif

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