Snapshot A 13-year-old boy presents with pain in his left groin, hip, and thigh. His mother notices a limp when he walks. The patient denies any recent significant trauma to his left lower extremity. On physical exam, his gait is antalgic. With the patient in the supine position, there is external rotation and abduction of the thigh with passive flexion of the hip. A radiograph of the affected hip is performed, which demonstrates inferior displacement of the left epiphysis. Introduction Clinical definition a hip disorder common in adolescents in which the head of the femur slips off the neck of the femur inferiorly and posteriorly, often due to mechanical overload Etiology Pathogenesis unstable growth plate (femoral physis) from mechanical overload causing excessive shear force on the growth plate growth spurts causing rapid cellular proliferation in growth plate change in vasculature resulting in suboptimal blood supply to the growth plate unstable growth plate can cause slippage of the femoral epiphysis Associated conditions endocrine disorders affecting bone metabolism hypothyroidism (most common) growth hormone deficiency multiple endocrine neoplasia Down syndrome renal osteodystrophy Epidemiology Demographics male > female children and adolescents 8-16 years of age more common in black and Hispanic children Risk factors obesity growth spurt Presentation Symptoms pain in the groin, hip, thigh, or ipsilateral knee without inciting trauma painful limp Physical exam Drehmann sign while in the supine position, hip externally rotates and abducts with passive hip flexion antalgic or waddling gait externally rotated leg on the affected side inability to bear weight limited range of motion of the hip Imaging Radiography indication for all patients to confirm diagnosis and grade severity recommend view anteroposterior and frog-leg lateral findings widening of joint space decrease in epiphyseal height Steel sign double density from superimposition of epiphysis and metaphysis Studies Making the diagnosis most cases are clinically diagnosed and confirmed with radiography Differential Legg-Calve-Perthes disease distinguishing factor in younger children with radiography showing joint effusions and increased width of the femoral neck not treated with surgery Treatment Conservative non-weight-bearing clutches or wheelchair indication for all patients while awaiting surgery Operative surgical fixation with screw indication for all patients prophylactic screw fixation of contralateral hip indications may be considered for patients, as there is a risk of the disease in contralateral hip later in life usually for patients < 10 or > 16 years of age Complications Avascular necrosis of hip Chondrolysis loss of joint cartilage Osteoarthritis Prognosis May recur even with stabilization