Slipped capital femoral epiphysis (SCFE) is one of the most common adolescent hip disorders and is characterized by a displacement of the capital femoral epiphysis as a result of anatomic disruption occurring at the proximal femoral physis.  This can result in translation of the epiphysis relative to the metaphysis, most commonly in a varus deformity (medial and posterior epiphyseal displacement relative to the metaphysis).[2,3]
It typically presents in adolescents between the ages 8 and 16 years, with a greater incidence in obese populations.  The majority are idiopathic, however, atypical SCFEs are usually secondary to endocrine disorders (ie thyroid or parathyroid disease), renal failure, or radiation therapy. The pain is often referred and felt anteriorly in the thigh to distally into knee as opposed to in the hip or groin itself.
SCFEs can be classified by their stability, acuity, and degree of displacement. The classification of SCFEs by physeal stability most accurately predicts the risk of avascular necrosis (AVN) and rely on clinical and radiographic features.[3,7] Clinically stable SCFEs are defined as slips in which walking and weight-bearing are still possible. [3,7] Radiographically stable SCFEs demonstrate meatphyseal remodeling and the absence of a hip effusion by ultrasonography.  Clincally unstable SCFEs are defined occur when the when the patient is unable to weight-bear. [3,7] Radiographically unstable SCFEs are defined by the lack metaphyseal remodeling and the presence of a hip effusion.  Stable SCFEs have a minimal risk of AVN compared to unstable SCFEs, whereby the risk is up to 50%. 
SCFEs most commonly present chronically, defined as symptoms lasting greater than 3 weeks at presentation.  Acute SCFEs present within 3 weeks of symptom onset.  Acute on chronic SCFEs occur when an acute exacerbation of symptoms occurs in a patient already experiencing symptoms for greater than 3 weeks. 
The severity of SCFEs is also a good prognostic indicator for the future development of degenerative hip disease and severity is classified by the degree of displacement compared to the unaffected side: [11,12]
* mild slips if there is < 30 degrees
* moderate if there is between 30 and 50 degrees
* severe if there is > 50 degree
Pain can be either localized to the hip, thigh, or knee on the affected side.
Patients usually have an altered gait.
Affected leg most commonly held in an externally rotated position and may be shortened.
Range of motion testing will provoke pain and may decreased internal rotation, abduction, and flexion.
Passively flexing the affected hip from an extended position may induce internal rotation of the affected leg.
XRay: AP view: Widening, lucency, and irregularity of the physis.  “Blanch sign of Steel”: metaphysis projected as a semicircular area of increased density on the proximal femoral neck (present in posterior translation of the epiphysis).  Alteration to the intersection of Kleins line (line along the femoral neck which normally intersects the lateral portion of the femoral head) with the femoral head.
Lateral/Frog-leg views are usually necessary to confirm the diagnosis.
Most cases can be diagnosed with plain films, however early slips and atypical cases may require additional imaging modalities including ultrasound, CT, and MRI.
The main goal of treatment is to prevent AVN and chondrolysis.[1,19] All patients with a diagnosed SCFE should be made nonweight-bearing until a consultation with a pediatric orthopedic surgeon for consideration of surgical stabilization. 
Dr. David Lawrence (Sept 2, 2014 PR ND)
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