This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Orthopaedics
Not a Radiological sign of Perthe's disease 
Select and explain. 
A. Widening of Joint space, B. Lateral sub luxation of femur head, C. Rotting picket fence appearance of femur neck, D. Epiphyseal calcification
D: Epiphyseal calcification
Answer: D: Epiphyseal calcification 
Explanation: None