Occult Hip Injury: 18-Month Old Won't Bear Weight
Radiology Cases in Pediatric Emergency Medicine
Volume 2, Case 11
Loren G. Yamamoto, MD, MPH
Kapiolani Medical Center For Women And Children
University of Hawaii John A. Burns School of Medicine
An 18 month old male was brought to a rural
emergency department because of pain in his right hip
and refusal to walk since yesterday. He was well until
he was walking up a wheelchair ramp and somehow fell
off the side of it onto his right leg. Since then, his
mother noted him to be in pain whenever she moves
that leg. He refuses to walk. As best as she can tell,
his pain appears to be in the right hip or thigh. He has
no history of fever, chills, other joint pains, joint
swelling, or skin infections. He was given
acetaminophen for pain control but this does not seem
to help much.
Exam: T37.0 (tympanic), P110, R28, BP 100/55.
He was alert in no distress. He does not appear to
move his right hip very much. He does not appear to
have a position of preference for the right hip.
Specifically, he does not favor the external rotation
position. He moves his toes well. He moves his entire
left lower extremity well. He seems to be tender around
the right thigh and possibly the hip, but it is difficult to
localize this with certainty as his mother has noted as
well. No joint swelling is noted. No long bone
deformities or swellings are noted. His pulses and
perfusion are good.
Radiographs of his right hip and femur are obtained.
No visible fractures are identified. The spaces in the
hip joints appear to be symmetric on both sides. His
condition is discussed with an orthopedic surgeon at a
tertiary center who agrees to see the patient the next
day if his parents are agreeable to this. His parents are
informed of the negative radiographs. Other diagnostic
possibilities are discussed with them. They prefer to
see the orthopedic surgeon tomorrow rather than
initiate a partial laboratory work-up in the emergency
department.
The next day (two days post injury), he is evaluated
by the orthopedic surgeon who notes similar exam
findings and reviews the radiographs taken in the
emergency department. No radiographic abnormalities
are detected by the orthopedic surgeon. Although there
is no history of fever, the patient is sent to the
laboratory for a CBC, blood culture, and erythrocyte
sedimentation rate. The CBC is unremarkable and the
ESR is normal (4 mm/hr).
An ultrasound of the right hip is obtained which fails
to demonstrate any joint effusion. A radionuclide bone
scan is done which shows no definite focal areas of
abnormally increased blood flow. The delayed static
bone images show mildly increased tracer localization
along the entire length of the femur most likely
indicative of a femur fracture. However, the degree of
tracer localization is very much less than is typical for a
fracture.
At this point, there is no radiographic evidence of a
fracture. However, the history indicates that an injury
led to the patient's current symptoms. The radionuclide
study is suggestive of a fracture. There is no evidence
to support the possibility of transient (toxic) synovitis,
any type of acute arthritis, or avascular necrosis of the
right hip. There is no laboratory evidence to suggest
other inflammatory processes. A repeat set of
radiographs is ordered.
View Femur Radiographs.
The initial set of radiographs (from the rural ED)
showed AP and frog views of the pelvis and right femur.
The current set of radiographs shown here includes
(from left to right) AP, lateral, and oblique views. Only
the pertinent parts of the radiographs are displayed in
these images. The actual radiographs contained much
wider views of the pelvis and the knee. No
abnormalities were detected in any of these films.
Another oblique view was taken.
View Fourth Film.
Do you see anything here.
A definite fracture is noted on this view. The
fracture line is very thin (hairline) and only visible if
taken at a very specific angle. The previous six
radiographs of the femur failed to demonstrate this. A
large fracture will probably show up on all views of the
injured area. Smaller fractures may be visible at certain
angles, but usually can be visualized with an AP,
lateral, or oblique view. Very small fractures may only
be visible at very specific angles such as in this case.
Some fractures are not seen easily on plain
radiographs. Radionuclide bone scanning, CT, MRI, or
follow-up plain radiographs may be necessary to
diagnose such fractures. It should be made clear to
patients that a negative set of radiographs does not
totally rule out a fracture.
This patient received a comprehensive evaluation to
investigate the possibility of other orthopedic conditions.
However, from the beginning, his presentation was
most consistent with a fracture. In many such
instances, clinical suspicion and perseverance are what
is necessary to make an occult diagnosis. Give credit
to the orthopedic surgeon who persevered in this case.
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