What is the most important and severe complication of developmental dysplasia of the hip?

• A. Fracture of the femoral neck
• B. Avascular necrosis of the capital femoral epiphysis
• C. Ligamentous laxity
• D. Paralysis of the sciatic nerve

Answer: (B)

Avascular necrosis of the femoral head occurs when the blood supply to the capital femoral epiphysis is disrupted by the abnormal hip in developmental dysplasia. This loss of perfusion leads to death of bone tissue, causing collapse and deformity of the femoral head, joint incongruity, and early osteoarthritis. These changes result in permanent functional impairment and often require complex procedures later in life, making AVN the most serious and impactful complication. While fractures, ligamentous laxity, or sciatic nerve injury can occur in various contexts, they do not carry the same predictable, long-term devastation to the hip joint as AVN does in DDH.