![]() In normal hip, the line intersects the lateral part of the superior femoral epiphysis. On the AP view, a line is drawn along the superior border of the femoral neck. Klien's line is a radiographic finding used to detect SCFE on plain radiographs. Radiographs should be bilateral to allow for comparison. The evaluation of patients with suspected SCFE should begin with bilateral hip radiographs with anteroposterior (AP) and frog-leg lateral views. Additionally, the patient may have a shuffling, Trendelenburg, or antalgic gait or have a complete inability to bear weight. The patient may demonstrate Drehmann sign which is obligatory external rotation with passive flexion of the hip to 90 degrees. There would be loss of hip flexion, abduction, and internal rotation. On examination, a limited internal rotation of the affected extremity can be present, and passive internal rotation may elicit pain. The patient may have a preference to sit with the affected leg crossed over the other. While most patients will not report any history of trauma or injury before the onset of symptoms, a history of injury or trauma does not exclude the possibility of SCFE. Patients with SCFE on average have 4-5 months of symptoms prior to diagnosis however, patients with SCFE may also present with less than 3 weeks of symptoms. Knee pain is usually due to pain activation of the medial obturator nerve. Pain is most often reported in the hip (52%) however, pain associated with SCFE may also be reported in the groin (13.9%), thigh (35%), or knee (26%). The clinician should always consider SCFE in a pre-adolescent, adolescent, or young adult patient with a complaint of atraumatic hip, thigh, or knee pain, particularly if associated with limping or inability to bear weight. SCFE is a Salter-Harris type I fracture that can be differentiated with preceding epiphysiolyis, more steady displacement, and intact periosteum in chronic cases or partially torn in acute cases. That includes: the physis being in a vertical position more susceptible to shear forces, thinning and weakening of the perichondrial ring of la Croix along with unlocking of the mamillary processes of the physis further destabilizing it. In adolescence, a combination of factors puts the physis at high risk of slippage. This slippage occurs at the level of the hypertrophic zone of the physis. The epiphysis stays in the acetabulum, and the metaphysics externally rotates with anterior translation. Conditions such as obesity increase the mechanical weight and force transmitted, whereas certain endocrine or renal disorders may contribute to the weakening of the physis. It is hypothesized that displacement occurs due to a high physiologic axial load transmitted across a relatively weak physis.
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