Posterior and inferior displacement of the femoral head in relation to the femoral neck at the proximal femoral growth plate.

Epidemiology:- Most common hip disorder in adolescents.- Peak incidence: 10-16 years (often occurs during a growth spurt)- Sex: ♂ > ♀

Risk factors:- Obesity- Family history- Trauma (e.g., sports-related injury or fall)

Clinical features:- Acute, chronic (3 weeks to several months), or acute on chronic onset- Dull pain in the medial thigh, knee, groin, or hip pain (often left > right)- Sudden limp- Reduced internal rotation and abduction- Patients may hold their hip in passive external rotation- Drehmann sign positive: external rotation and abduction during passive flexion of the affected hip in supine position- Bilateral in ∼ 40% of cases

Diagnostics:- Confirmatory test: x-ray in frog-leg position→ Widening of the joint space→ The femoral head is displaced posteriorly and inferiorly in relation to the femoral neck.- Consider laboratory tests to exclude endocrinopathies in patients with an atypical age of onset or short stature.

Treatment:- Avoid weight bearing before stabilization- Urgent surgical internal fixation with pinning of the femoral head- Prophylactic fixation of the contralateral hip

Complications:- Avascular necrosis of the femoral head- Early hip osteoarthritis