This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Avascular Necrosis & Osteochondroses, Subject name: Orthopaedics
[{'content': 'Commonest age of Perthes disease is: \nSelect and explain. \nA. 5-10 years, B. 10-20 years, C. 20 - 25 years, D. 20 - 30 years', 'role': 'user'}, {'content': "Answer: A \nExplanation: (5 - 10 years): Ref: 269-M, 422-APERTHES' DISEASE: (Coxa plana, Pseudocoxalgia) A painful disorder of childhood characterized by avascular necrosis of the femoral head.* The disease commonly in boys in age groups of 5 - 10 years* Limping or stiffness* Limitation of abduction and internal rotation and shortening* Age is the most important prognostic factorGuidelines of Treatment1. Children under 6 years of age - Symptomatic treatment including a period of traction and there after reduced activity, is appropriate2. Children aged 6-8 years - In this the bone age is more important than the chronological age(I) Bone age at or below 6 years - Symptomatic treatment abduction brace(II) Bone age over 6 years - Abduction brace or osteotomy3. Children 9 years and older - Operative containment is the treatment of choice", 'role': 'assistant'}]