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 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