This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Osteochondritis and Avascular Necrosis, Subject name: Orthopaedics
A 7 year old boy presents to the OPD with a painless limp. On examination, you observe that abduction and internal rotation of left hip are restricted. While attempting to flex the hip, the knee goes toward axilla. What is your probable diagnosis? 
Select and explain. 
A. Septic ahritis of hip, B. Tuberculosis ahritis of hip, C. Cong dislocation of hip, D. Pehes disease
D: Pehes disease
Answer: D: Pehes disease 
Explanation: Pehes disease: Male > Female 4-8 years of age, self limiting/resolving Bilateral in 10-12 % of the cases Lateral subluxation of the femoral head Speckled calcification lateral to the capital epiphysis Gage sign-a radiolucent 'V' shaped defect in the lateral epiphysis and adjacent metaphysis Sagging Rope Sign--metaphyseal sclerotic band painless limp is the key point for the diagnosis. Examination findings: extremes of all movements are diminished. When the hip is flexed it may go into obligatory external rotation (Catterall's sign) and knee points towards axilla. (Normally goes towards mid-clavicular region)