Sudden Thigh Swelling in a 6-Week Old Infant
Radiology Cases in Pediatric Emergency Medicine
Volume 2, Case 17
Rodney B. Boychuk, MD
Kapiolani Medical Center For Women And Children
University of Hawaii John A. Burns School of Medicine
     This 6-week old male was well until two days prior to 
presenting to the ED when his left thigh suddenly 
became swollen.  His mother, who cares for him both 
day and night, states that there is no history of trauma.  
She denies any rough play, shaking, or any chance of 
trauma, such as rolling off the bed or the couch.  
Further questioning reveals that sometimes the infant's 
father, paternal grandmother, paternal grandfather, and 
paternal aunt, all living in the same household, also 
care for the infant.  There is also a one-year old female 
sibling a 2-year old female cousin, and great 
grandparents all living in the same house, who 
sometimes play with the infant.  Both mother and father 
are 18 years of age.  This infant was born full-term with 
a birth weight of 3.4 kg.  Immunizations are up to date 
(hepatitis B vaccine X2).  No allergies are noted.  He is 
on no medications and has had no illnesses, 
hospitalizations or surgery since birth.  His mother 
states that the thigh swelling is somewhat less that the 
day prior, but the child still will not move his leg, which 
is her greatest concern.
     Exam VS T37.4 (rectal), HR 160, R30, weight 4.2 
kg.  Quiet, well developed, well nourished, active and 
alert.  His anterior fontanelle is flat and soft.  Pupils are 
equal and reactive to light.  The red reflex is present, 
and the fundi (exam with difficulty) appear clear.  There 
are no bruises noted anywhere on the head or 
elsewhere on the body.  Tympanic membranes appear 
normal.  Chest reveals no bony deformity, with good 
aeration bilaterally.  Heart regular with a grade 2/6 
vibratory systolic murmur present at the left sternal 
border.  The abdomen is soft.  Active bowel sounds are 
noted.  No masses are evident, and no bruising is 
noted.  Normal male external genitalia are noted.  
Except for an abnormal left lower extremity, other 
extremities appear normal.  The left thigh is very 
swollen, with the foot being somewhat externally 
rotated.  Pedal pulses are good, and capillary refill time 
is less than 2 seconds.  The thigh is very firm and 
warm, but not discolored.  No spontaneous movement 
is present in the left leg, and the leg is tender to touch 
(baby cries when the leg is touched).
     Radiographs of the left lower extremity are done.

View radiograph.

     This radiograph shows an obvious oblique fracture 
of the proximal shaft of the left femur, with superior and 
anterior displacement of the distal fracture fragment.  
There is also a hairline fracture component involving the 
middle and distal shaft of the left femur.  On the lateral 
view (left image), this can be seen as a faint oblique 
linear lucency over the distal 1/3 of the femur.  On the 
AP view (right image), this can be seen as a faint linear 
lucency extending from the obvious fracture above, 
downward and through the mid femur and continuing 
obliquely into the distal 1/3 of the femur.  The left knee, 
tibia and fibula are unremarkable.
     Because of the strong suspicion of intentional 
trauma (child abuse), the infant is hospitalized and a 
skeletal survey is done.  The following positive 
radiographs are shown:

View Right UE and LE.

     The upper extremity radiograph (left image) reveals 
an old fracture of the right proximal radius.  There is 
some periosteal elevation surrounding the fracture 
indicating that the fracture did not occur recently.  The 
lower extremity radiograph (right image) reveals a 
healing fracture of the right tibia with periosteal reaction 
along the entire shaft of the right tibia.  The fracture line 
itself is not easily identified.

View Torso radiographs.

     The vertebral body of T12 appears much flatter than 
the other thoracic vertebra.  T10 and L2 may also be 
slightly flattened.  Because of the difficulty in diagnosing 
these as vertebral body compression fractures, a bone 
scan is done for correlation.

View Bone Scan.

     This bone scan confirms the long bone fractures.  
There is an obvious hot spot in the right radius.  The 
entire left femur and right tibia are hot.  There is also a 
hot spot over the occiput suggesting a fracture or a 
subperiosteal contusion.  There are no obvious 
vertebral hot spots suggesting that the flattened 
vertebral bodies may not represent fractures.  This 
study is a "planar" bone scan.  More conventional bone 
scanners utilizing the SPECT (single photon emission 
computed tomography) method are more accurate in 
identifying such fractures.
     The remainder of the skeletal survey was negative.  
The skull radiographs were not able to identify any 
fractures.  A CT scan of the head was negative for 
fracture or brain injury.  An ophthalmology examination 
found no retinal hemorrhages.  The infant remained 
medically stable.  He was feeding well and gaining 
weight.  After being fitted with an orthopedic Pavlik 
harness, child protective services placed the infant in a 
foster home.  The young children living in the household 
were also removed and placed in foster homes.

Discussion
     Physical abuse is any non-accidental injury to a child 
caused by a parent or caretaker.  This might be 
shaking, beating, burning, scalding, poisoning, or other 
trauma.  Physicians must maintain a high index of 
suspicion, particularly when the history of an injury is 
inconsistent with physical findings.  Excessive delay in 
seeking medical treatment, trauma inconsistent with 
age-related injury, unexplained or multiple trauma, or 
sibling-inflicted injuries must raise suspicion of abuse.
     Physical abuse most often is a pattern of repeated 
behavior, with bruises and welts being the most 
frequent evidence of such.  Typical sites for inflicted 
bruises include the neck (choke marks), upper lip and 
frenulum (forceful feeding), ear lobe (pinch or slap 
marks), cheeks (slap marks), buttocks and lower back 
(paddling), the genital area and inner thighs.  Human 
bite marks leave concentric bruises that contain 
individual teeth marks.  If the point-to-point distance 
between the canines (eye teeth) is greater than 3.0 cm, 
the injury was inflicted by someone with permanent 
teeth.  Dating bruises is also important, and multiple 
colors suggest multiple times of injury.  An initial bruise 
would be swollen, tender, and bright red-to-blue.  
Between days 1-5, a combination of colors can be 
seen, being red, blue, or purple.  The bruise will change 
to a green color between days 5-7, a yellow color 
between days 7-10, and a brown color after 10 days.
     Child abuse is a common cause of burns.  Scald or 
immersion burns are the most common, bearing the 
characteristic glove or stocking pattern that is observed 
on physical examination.  With a water temperature of 
145 degrees or greater, an almost instantaneous 
full-thickness burn will occur.  With a water temperature 
of 130 degrees, it takes approximately 30-45 seconds.  
Contact burns from a hot metal object or cigarette are 
another type of burn seen with child abuse.
     Head injuries are the most common cause of death 
from child abuse.  In 1946, Dr. John Caffey reported six 
children who had chronic subdural hematomas in 
association with multiple fractures of the peripheral 
skeleton.  In 1974, Caffey described a syndrome of 
severe central nervous system injury caused by "the 
shaken infant syndrome."  Shaking produces a whiplash 
injury to the brain tissue, causing injury to the axons 
and bridging vessels that leads to subdural hematoma 
and/or subarachnoid hemorrhage.  Retinal 
hemorrhages and changes in sensorium are 
characteristic findings resulting in a clinical picture of 
coma, apnea, seizures, sepsis or other non-specific 
neurological signs (see Case 1 in Volume 1).
     Abdominal injury is the second most common cause 
of death among battered children.  Ruptures of the 
spleen, liver or bowel caused by a punch or kick can 
result in the above with no visible bruises or marks on 
the abdomen in over half the cases.  Rupture of the 
bladder may also occur.
     A child who presents with multiple fractures at 
multiple sites and in various stages of healing should be 
considered abused until proven otherwise.  
Epiphyseal-metaphyseal injury is virtually diagnostic of 
physical abuse in an infant, since an infant cannot 
generate enough force to fracture a bone at the 
epiphysis.  Fractures secondary to abuse are more 
commonly seen in children less than 3 years of age.  
Conversely, less than 10% of children over 5 years of 
age who are abused sustain fractures.  In general, a 
complete skeletal survey should be done on all children 
less than 2 years of age who are possible abuse 
victims.
     A spiral or oblique fracture of long bones is 
produced by a twisting mechanism.  Whether accidental 
or non-accidental, a large amount of force is required to 
produce a fracture of the femur.  A direct blow causing 
a transverse fracture can also be seen with major 
violence.  Young children who are not ambulatory 
cannot produce enough force to fracture their femur.  A 
history of getting his/her leg "caught in the crib" should 
be viewed with suspicion.
     Rib fractures are highly suggestive of abuse in 
infants and young children.  Squeezing usually 
produces fractures of the posterolateral aspects of the 
ribs.  Shaking or choking a child has been shown to 
produce fractures anteriorly in the first or second ribs.  
Rib fractures secondary to trauma that is NOT child 
abuse tend to occur in the middle or anterior part of the 
rib cage.
     Spinal fractures are infrequently seen in child abuse 
cases.  The mechanism is usually one of compression, 
as a child is forcibly seated into a chair or onto a 
tabletop.
     A skeletal survey is often diagnostic of the child 
abuse syndrome.  The survey should include, at a 
minimum, two views of the skull, lateral view of the 
thoracolumbar spine, and anterior-posterior views of 
both upper extremities, hands, pelvis, and both lower 
extremities, including the feet.  There are several 
radiologic signs suggestive of abuse.  These include 
healing fractures, multiple fractures, fractures of 
unusual locations, and metaphyseal fractures.  The 
typical radiographic appearances have been described 
as:  a) "corner fractures", b) "bucket handle" fractures, 
and c) subperiosteal hematoma with new bone 
formation.  Other radiographic findings suggestive of 
abuse include posterior rib fractures, spinous process 
fractures, sternal fractures, complex skull fractures, and 
diaphyseal spiral and oblique fractures.  Fractures 
showing different stages of healing are almost 
pathognomonic of abuse.  Any fracture which already 
shows signs of healing suggests that the fracture is at 
least ten days old.
     Technetium 99 bone scanning has been shown to 
be highly sensitive when used to assess skeletal injury, 
particularly in occult areas not easily accessible to 
clinical exam.  This scan is frequently "hot" for many 
weeks during healing.
     American law requires the reporting of any 
suspected abuse.  A report of suspected abuse is a 
responsible attempt to protect a child.  A significant 
number of children may be further abused if not 
protected and may even die from further injury.  
Physicians must consider abuse as a potential 
diagnosis and maintain a high index of suspicion in 
order to prevent further morbidity and mortality in 
children unable to speak for themselves.

References
     1.  Gibson G, Block R.  Child Abuse.  In:  Surpure 
JS (ed).  Synopsis of Pediatric Emergency Care, 1993, 
Boston, Andover Medical Publishers, pp. 367-372.
     2.  Black GB.  Child Abuse Fractures.  In:  Letts RM.  
Management of Pediatric Fractures, 1994, New York, 
Churchill Livingstone, pp. 931-944.
     3.  Caffey J.  Multiple Fractures in Long Bones of 
Infants Suffering from Chronic Subdural Hematoma.  
American Journal of Radiology 1946:56;163.
     4.  Caffey J.  On the Theory and Practice of Shaking 
Infants.  American Journal of Disease in Children 
1972:124;161.
     5.  O'Conner JF, Cohn J.  Diagnostic Imaging of 
Child Abuse.  In:  Kleinman PK (ed).  Diagnostic 
Imaging of Child Abuse, 1987, Baltimore, Williams & 
Wilkins, 1987, p.112.

Return to Radiology Cases In Ped Emerg Med Case Selection Page

Return to Univ. Hawaii Dept. Pediatrics Home Page

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