Radiology Cases in Pediatric Emergency Medicine
Volume 1, Case 15
Lynette L. Young, MD
Kapiolani Medical Center For Women And Children
University of Hawaii John A. Burns School of Medicine
A 9 year old male fell off a slide and landed on his
outstretched left arm. He now presents to the ED with
pain in his left forearm and elbow. There is no history
of head trauma. He denies having a headache, and
there is no nausea or vomiting. His past medical
history is unremarkable.
Exam: Vital signs T37, P76, R20, BP110/73. He
is alert and oriented but in obvious discomfort
secondary to left arm pain. Pupils are equal and
reactive. His left clavicle, shoulder and humerus are
nontender. His left hand and wrist (including the
anatomic snuffbox) are also nontender. He is tender
over the proximal aspect of his left forearm. He is
unable to flex, extend, supinate, or pronate at his left
elbow. He is able to move all his fingers well. Distally,
he is neurovascularly intact. Capillary refill time is 2
seconds. Radiographs of his left forearm and elbow
View forearm radiographs.
View elbow radiographs.
There is an obvious mid-shaft ulnar fracture. Do you
see anything else wrong with the radiographs? Look at
the radiographs again.
The radial head should point at the capitellum in all
views. A line drawn down the long axis of the radius
(radial head) should intersect the capitellum in all views.
Review Case 12 (Radiographic Examination of the
Elbow) for further discussion on the radiocapitellar line.
In this case, the line drawn down the long axis of the
radius does not intersect the capitellum. This indicates
that the radial head is dislocated. In this case, there is
an anterior dislocation of the radius. There is a
prominent anterior fat pad visible, which is probably
within normal limits. No posterior fat pad sign is seen.
The patient was taken to the OR for closed
reduction under general anesthesia.
Teaching points and Discussion.
1. In 1814, Monteggia first described the
combination of proximal ulnar fracture with anterior
dislocation of the radial head. The Monteggia
fracture-dislocation now includes several different types
of ulnar fractures with radial head dislocation. In
children, the classic form of Monteggia's injury is
uncommon. Monteggia fracture-dislocation comprises
2% of all elbow fractures in children.
2. Monteggia's injury can easily be overlooked. In
general, isolated ulnar fractures are very rare. With any
type of ulnar fracture, it is important to have
radiographs of both the forearm as well as the elbow
joint. Recognition of a Monteggia's injury is critical
because if the radial head is not reduced, it could lead
to permanent disability.
3. The most common mechanism of injury in
children is hyperextension at the elbow joint. This
results in fracture of the ulna with anterior angulation
and an anterior dislocation of the radial head. Another
mechanism is hyperpronation of the forearm with a fall
on an outstretched hand. The annular ligament is either
torn or is displaced over the radial head.
4. On examination, there may be tenderness,
swelling, and deformity at the site of the ulnar fracture.
This can sometimes distract the examiner from noticing
injury at the elbow. The dislocation of the radial head
may often be palpated. With any obvious forearm
deformity, it is important to examine the elbow and wrist
for injury also. The presence or absence of tenderness
on palpation of the radial head should be noted.
5. Radiographs of the forearm, elbow, and wrist
should be obtained. Always remember to include the
joint above and below the site of injury. It is important
to have a true lateral of the elbow along with the
anteroposterior view. A line drawn through the long
axis of the radius should pass through the center of the
capitellum in all views. With radial head dislocation, this
line does not intersect the center of the capitellum.
6. The ulnar fracture in Monteggia's injury is most
often at the proximal to middle third of the ulna.
Sometimes the fractureis not complete; there may be
a greenstick fracture or even bowing of the ulna
associated with the radial head dislocation. The radial
head dislocation may be anterior, posterior, or lateral.
View another example: Lateral view.
The lateral view shows a large anterior fat pad and a
small posterior fat pad indicating a joint effusion. You
may have to adjust the contrast and brightness controls
on your monitor to appreciate this. There is a tiny
cortical angle noted on the inferior margin of the radial
head metaphysis where it crosses the ulna, indicating a
subtle radial head fracture. The radius is NOT pointing
directly at the capitellum. This indicates dislocation of
the radial head. The AP view is more of an oblique
view. It shows a fracture of the olecranon. The radial
head metaphysis shows a sharper cortical angle,
making the radial head fracture more obvious. This is a
very subtle example of a Monteggia injury (ulna fracture
with radial head dislocation). Although the radial head
fracture is not necessarily part of the Monteggia injury,
the same forces resulting in radial head dislocation
probably caused the radial head fracture as well.
7. Do not splint or cast a Monteggia's injury and
discharge from the ED. This requires an immediate
orthopedic referral. The radial head dislocation must be
reduced by an orthopedic surgeon as soon as possible.
In most pediatric cases, a closed reduction under
general anesthesia can be done. Sometimes open
reduction of the radial head dislocation and internal
fixation of the ulnar fracture are required. With early
recognition and treatment, there is usually a good
8. The posterior interosseous branch of the radial
nerve is the most commonly injured nerve associated
with Monteggia's injury. This nerve injury is usually
self-limited and resolves. This nerve innervates the
deep extensor muscles (extensor digitorum, the
extensor digiti minimi, the extensor carpi unlaris, and
the extensor indicis).
9. Complications of Monteggia's injury include
recurrent dislocation of the radial head, persistent
subluxation of the radial head, nerve injuries, and
limitation of elbow range of motion.
1. Joffe M. Monteggia's fracture and radial head
dislocation. In: Barkin RM (ed). Pediatric Emergency
Medicine Concepts and Clinical Practice. Chicago,
Mosby Year Book, 1992, pp. 353-354.
2. Bachman D, Santora S. Orthopedic Trauma. In:
Fleisher GR, Ludwig S (eds). Textbook of Pediatric
Emergency Medicine, third edition. Baltimore, Williams
and Wilkins, 1993, pp. 1260-1261.
3. Letts RM. Monteggia and Galeazzi Fractures.
In: Letts RM (ed). Management of Pediatric Fractures.
New York, Churchill Livingstone, 1994, pp. 295-313.
4. Lincoln TL, Mubarak SJ. Isolated Traumatic
Radial-Head Dislocation. Journal of Pediatric
Return to Radiology Cases In Ped Emerg Med Case Selection Page
Return to Univ. Hawaii Dept. Pediatrics Home Page