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 
     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 
     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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Web Page Author:
Loren Yamamoto, MD, MPH
Associate Professor of Pediatrics
University of Hawaii John A. Burns School of Medicine