Thigh and Knee Pain in an Obese 10-Year Old
Radiology Cases in Pediatric Emergency Medicine
Volume 2, Case 10
Loren G. Yamamoto, MD, MPH
Kapiolani Medical Center For Women And Children
University of Hawaii John A. Burns School of Medicine
     This is a large 10-year old male who presents to the 
acute care clinic with a two week history of right thigh 
and knee pain.  He states that the pain is mainly in his 
thigh (points to his upper thigh) but radiates down to his 
knee.  He was playing basketball when he collided with 
another player and fell.  He noted severe pain in his 
thigh and had to limp home, mostly on his left leg.  
Since then, he has been complaining of pain in his right 
thigh when bearing weight.  However, the pain would 
subside when lying in bed.  He did not appear to 
improve much and he was finally brought to an acute 
care clinic.  He had no history of fever, rash, chest 
discomfort, or pains in other joints.
     Exam VS T37.0 (oral), P66, R20, BP 112/65, weight 
69.3 kg (>>95th percentile), height 152 cm (>95th 
percentile).  Alert, cooperative, in no distress while lying 
down.  Obese and large for age.  HEENT 
unremarkable.  Neck normal range of motion.  Heart 
regular without murmurs.  Lungs clear.  Abdomen round 
contour, soft, non-tender, bowel sounds active.
     Right lower extremity:  Moderate tenderness in the 
upper anterior thigh.  Severely tender in the hip.  Pubic 
symphysis non tender.  Mid thigh and knee non-tender.  
Tibia/fibula and foot non-tender.  No joint swelling 
noted.  Range of motion about the hip is not done.  
Range of motion of the right knee is good.
     Left lower extremity:  Mild tenderness of the hip on 
palpation.  Mild tenderness on range of motion testing.  
Good range of motion.  Otherwise unremarkable.
     Although his chief complaint is thigh pain, his exam 
indicates that his injury is in his hip.  He probably 
perceives this hip pain as pain in his upper thigh and 
this is how he expressed his pain to others.  
Radiographs of the hips are ordered.

View hip radiographs.

     A common pitfall is to focus on the patient's chief 
complaint.  In this case, focusing on the thigh may lead 
one to focus on the mid thigh and ignore the hip.  His 
exam clearly points to his hip as the source of his pain.  
Whenever a patient complains of thigh pain, always 
examine the hip since this is frequently the source of 
the thigh pain.  Hip injuries may also present with knee 
pain.  Whenever a patient complains of knee pain, 
always examine the hip since this is occasionally the 
source of the knee pain.
     The history of his collision and fall suggests an acute 
injury such as a non-displaced fracture.  An obese child 
with hip pain in this age group should always raise the 
possibility of slipped capital femoral epiphysis.  His hip 
radiographs show a slipped capital femoral epiphysis on 
the right.  His left hip appears to be normal.  However, it 
is difficult to rule out an early slip on the left as well.  He 
is very heavy and he has been putting most of his 
weight on his left hip for two weeks because of the pain 
in his right hip.  He now has mild tenderness in his left 
     He is hospitalized and put at bedrest.  After a few 
hours of bedrest, his left hip is no longer tender.  His left 
hip exam is completely normal.  He is taken to the 
operating room for internal fixation of his right femoral 
capital epiphysis.
     The radiographic diagnosis of slipped capital femoral 
epiphysis (SCFE) can be subtle.  In this case, the 
physis appears to be wider and more lucent in the 
patient's right hip compared to his left.  This is probably 
due to SCFE, however, this sign cannot be relied upon 
alone.  The position of the femoral head epiphysis 
should resemble a cap over the physis.  Subtle cases 
may just show a slight malpositioning of the epiphysis.  
Examine the diagram of our patient's hips.

View diagram.

     The lines drawn along the superior border of the 
proximal femur metaphysis (the Klein line) should 
intersect part of the proximal femoral epiphysis.  The 
patient's right hip (left on the screen) shows the line just 
touching the lateral margin of the epiphysis.  This is 
abnormal, indicating that the femoral capital epiphysis 
has slipped inferiorly and medially.  The patient's 
normal left hip (right on the screen) shows the line 
intersecting the lateral part of the femoral epiphysis.  
This is normal.
     Some cases of SCFE are very obvious.

View obvious case.

     You don't need to draw the lines here to appreciate 
that the patient's left hip (right on the screen) is 
abnormal.  This is a severe left slipped capital femoral 
epiphysis.  However, the slipped capital femoral 
epiphysis on the right may not be as obvious, especially 
if the left hip distracted your attention.  This patient has 
bilateral SCFE, severe on the left, and moderately 
severe on the right.
     Slipped capital femoral epiphysis is a diagnosis that 
will occasionally present to an emergency department 
with acute, subacute, or chronic pain in the hip, thigh, or 
knee.   The diagnosis of SCFE is not difficult if it is 
considered.  However, patients may have vague 
symptoms that don't precisely point to the hip.  Their 
degree of pain may range from severe to non-existent.  
Their ambulatory ability may range from non-weight 
bearing to a normal gait.  The pitfall of misdiagnosing 
SCFE as a pulled muscle, a hip bruise, a hip sprain, a 
Charlie horse, or a knee sprain should be avoided by 
carefully examining the hip in any patient presenting 
with hip, thigh, or knee pain.
     Most SCFE patients prefer to keep their hip 
externally rotated.  A major clinical finding in SCFE is 
their inability to fully internally rotate their hip.
     SCFE can be detected radiographically in most 
instances.  In obvious cases, the epiphysis is obviously 
displaced.  In subtle cases, the epiphyseal plate 
(physis) may be widened or irregular compared to the 
normal side.  A line drawn along the superior border of 
the metaphysis (the Klein line) may intersect less of the 
epiphysis compared to the normal side (As noted in the 
     In other subtle cases, the physis may appear to be 
thinner than the normal side.  This can occur if the slip 
occurs posteriorly.  Early slips can be difficult to 
demonstrate radiographically.  AP views of the hips can 
only detect inferior and medial slips.  Early slips tend to 
slip only in the posterior direction.  Posterior slips are 
best seen on lateral views of the hips, but these are 
difficult to obtain.  CT scanning can be helpful for 
orthopedic surgeons, but this is not usually needed in 
the emergency department.  MRI scanning is not useful 
in SCFE.
     Treatment is largely the responsibility of the 
orthopedic surgeon.  However, one of the major goals 
of treatment is to prevent further slipping.  Further 
slipping cannot be prevented unless the diagnosis of 
SCFE is made on the initial presentation.  Avoid the 
pitfall of missing this diagnosis since sending the 
patient home with the wrong diagnosis will likely worsen 
the slip.  These patients should be put at bedrest.  
Simple traction is reasonable, however, it is best to 
discuss this with an orthopedic surgeon.

     Morrissy RT.  Slipped Capital Femoral Epiphysis 
(Chapter 24).  In:  Morrissy RT (ed).  Lovell and 
Winter's Pediatric Orthopedics, third edition.  
Philadelphia, JB Lippincott Co., 1990, pp. 885-902.

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