9.17 Subluxation of the Head of the Radius (Nursemaid’s Elbow)

agk’s Library of Common Simple Emergencies

Presentation

A toddler has received a sudden jerk on his arm causing enough pain that he holds it motionless. 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 pronation of the forearm. There should be no deformity, crepitation, swelling, or discoloration 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:

• 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 immobilization 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 arrn 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:

• 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

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:

• 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

-----------------------------------------------------
from Buttaravoli & Stair: COMMON SIMPLE EMERGENCIES © 
Longwood Information LLC 4822 Quebec St NW Washington DC 20016-3229 
1.202.237.0971 fax 1.202.244.8393 electra@clark.net
-----------------------------------------------------