Pediatric emergency medicine trisk 3972 3972
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with more severe disturbance of the epiphysis on radiographs have a poorer
prognosis.
ANNULAR LIGAMENT DISPLACEMENT (RADIAL HEAD
SUBLUXATION)
Current Evidence
“Nursemaid’s elbow” is the most common joint injury in pediatric patients,
usually occurring in children between 6 months and 5 years of age. The term
annular ligament displacement (ALD) is replacing radial head subluxation for this
entity because it is more anatomically correct. Displacement of the annular
ligament occurs as a result of traction on a pronated hand or wrist, causing the
ligament to slide over the radial head and become interposed between the radius
and capitellum. The absence of a history of traction on the arm in children with
ALD suggests there may be alternative mechanisms.
Except for a very slight increase in the distance between the radial head and
capitellum that can be seen on ultrasound, the relationship between radial head
and capitellum remains essentially unchanged, and radiographs are normal in
patients with ALD. The radial head is not abnormal and the annular ligament does
not necessarily tear when this injury occurs. The left elbow is more often affected
because adult caregivers tend to hold the child’s left hand with their dominant
right hand.
Clinical Considerations
Clinical Recognition
ALD can be strongly suspected from across the examining room. The child
generally holds the arm slightly flexed, against his or her body with the forearm
pronated. When left alone, the child does not appear to be in significant pain.
Parents may report a problem with the wrist or shoulder because, in their attempts
to assess these joints, inadvertent movement of the elbow causes pain. Physicians
can be similarly fooled, especially when a classic history of traction is not
obtained.
Initial Assessment/H&P
In up to half of the cases, a history of traction on the arm is not obtained, which
may suggest another mechanism for this injury or perhaps caregivers who are
reluctant to volunteer self-incriminating information. Astute clinicians should
suspect this injury even in the absence of the typical history.
