Pediatric emergency medicine trisk 3966 3966
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The pain with SCFE is often described as dull, vague, intermittent, and often
chronic in nature. The average duration of symptoms prior to diagnosis of SCFE
is 2 months and slip severity is correlated with delay in diagnosis. A history of
trivial injury is sometimes obtained, perhaps causing the additional slippage that
precipitates a medical evaluation. Acute onset of severe symptoms suggests acute
or acute-on-chronic slippage, sometimes referred to as “unstable” SCFE. These
patients are often unable to bear weight and may be in significant pain.
Examination findings in patients with SCFE include a resting position with hip
flexion and some external rotation. Range of motion of the hip, especially full
flexion, internal rotation, and abduction, is decreased and painful. Hip flexion
will often be associated with obligate external rotation. Patients with significant
displacement may have evidence of limb shortening. Occasionally, there is
tenderness of the hip anteriorly. Patients with more acute presentations should not
be forced to walk as part of the evaluation. Testing for full range of motion is
unnecessary once a decision to obtain radiographs has already been reached.
Diagnostic Testing
It is important for emergency physicians to have skill in interpreting plain
radiographs for SCFE. Radiographs of the hip should include two views because
SCFE is not apparent in one-third of cases in which a single AP view is obtained (
Fig. 121.14 ). On the AP view, widening of the physis is usually seen, even if the
displacement is absent. A line drawn along the lateral aspect of the femoral neck
on the AP view (Klein line) should intersect a small portion of the femoral
epiphysis in a normal hip, but will not in cases of SCFE. The epiphysis in SCFE
is almost always displaced posteriorly. The externally rotated frog-leg view turns
the posterior aspect medially and facilitates visualization of the offset between the
epiphysis and the metaphysis in cases of SCFE. A line along the inferior margin
of the proximal femur should smoothly continue over the physis and epiphysis in
an S shape. If there is discontinuity or abrupt bending of the line, SCFE should be
strongly suspected. The S-sign is more sensitive and specific for SCFE than Klein
line. Together, the S-sign and Klein line have a sensitivity of 96% and specificity
of 85% for SCFE. New bone formation may be visible with a chronic slip. When
radiographic findings are equivocal, comparison with the contralateral,
asymptomatic hip should be done with caution, given the possibility of bilateral
slippage with unilateral symptoms. Those with suspicious clinical presentations
but normal radiographs may have early SCFE or a “preslip” that may be detected
by MRI. There is emerging evidence that ultrasonography may be more sensitive
for SCFE than plain radiography.
