Femoral head avascular necrosis associated with metaphyseal aneurysmal bone cyst

A 12-year-old girl had an aneurysmal bone cyst in the proximal femoral metaphysis simultaneously with an avascular necrosis of the femoral head, as seen on radiological examination. No extension of the lesion across the growth plate into the femoral epiphysis was observed. The expansive behavior of this lesion (ABC) could have compromised the posterosuperior vascular supply of the femoral epiphysis, since no radiographic signs of fractures could be found. Vascular anomalies within the lesion that increase venous pressure could be another factor responsible for the decrease in the blood supply of the femoral epiphysis and could cause necrosis, hence compromising the morphology of the hip joint at maturity.