Which statement is not true about Perthes disease?

Ans. C. The bone age is same as that of the chronological ageThe bone age is typically lower than the chronological age by 1-3 years.Since the blood supply of the femoral capital epiphysis is affected, it is characterized by avascular necrosis and disordered enchondral ossification of the primary and secondary centers of ossification.Salient clinical features of Perthes disease:* Typically affects boys aged 4-8 years* Proximal thigh atrophy* Muscle spasm* Short Stature (Altered longitudinal growth of proximal femur)* Limitation of abduction and internal rotation* Antalgic gait* When the hip is flexed it may go into obligatory external rotation called Catterall sign.