Subluxation of the radial head is one of the most common pediatric
orthopedic injuries. This can occur in children whose age ranges
from less than 6 months to the preteens. The majority of radial head
subluxations occur between 1 and 3 years of age.1 It is
a rare injury before 1 year of age and after 8 years of age.
Historically, the classic mechanism involves axial or longitudinal
traction on an extended elbow with the forearm pronated. This often
occurs while someone is holding onto the child by the hand or wrist.
While being held, the child is then pulled or the child falls and
is suspended by the arm. The subluxation is seen more often in the
left arm than the right. This is due to more people being right-handed
and holding the child’s left hand or wrist while walking.
It is not uncommon, however, for the child to present with a history
of a fall or rolling over in bed.1
This orthopedic injury involves the region of the elbow (Figure
69-1). The annular ligament is a thick band that wraps around the
upper radial neck and radial head (Figure 69-1A).
It guides the radial head as the forearm moves through pronation
and supination. The injury causes the radial head to become partially
dislocated from its articulation with the ulna and the capitellum
of the humerus while the forearm is in a pronated state. The annular
ligament then slips proximally and its lateral end becomes entrapped
between the radial head and the capitellum (Figure 69-1B). The forearm becomes locked in pronation
due to the entrapped annular ligament. This condition is painless
as long as the forearm is held in pronation. Supination of the forearm
causes pain, so the child holds the extremity in pronation. The
act of supination would also spontaneously return the annular ligament
to its anatomic position and reduce the subluxation.
Anatomy of the elbow region. A. Normal
anatomy. B. A radial head subluxation.
Note the entrapped annular ligament.
Children will present in no apparent distress.2 They
are usually resting comfortably and have some reservation in using
the affected extremity. The arm will be held with slight flexion
of the elbow and pronation of the forearm (Figure 69-2A). The child may point to an area
of pain, but this is not often the case. A child may be much more comfortable
with the parent examining and questioning areas of tenderness as
opposed to the unknown and sometimes intimidating physician.
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