Avascular necrosis in developmental dysplasia of the hip most commonly affects which region of the femoral head?

• A. Femoral neck
• B. Greater trochanter
• C. Acetabulum
• D. Capital femoral epiphysis

Answer: (D)

In DDH, disruption of the femoral head’s blood supply in a growing child most often affects the capital femoral epiphysis—the part of the femoral head that ossifies last and relies on vessels entering the head. When the hip is dislocated or misaligned, the retinacular vessels supplying the epiphysis can be compromised, leading to avascular necrosis in that region. The femoral neck and greater trochanter have different vascular patterns and are not the typical sites for DDH-associated AVN, and the acetabulum is not part of the femoral head itself. Therefore, the capital femoral epiphysis is the region most commonly involved.