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
A 10 years old male with pain in left hip & limping on examination restricted abduction & internal rotation, probable diagnosis is - 
Select and explain. 
A. Septic arthritis of hip, B. Tuberculous arthritis of hip, C. Congenital dislocation of hip, D. Perthes disease
D: Perthes disease
Answer: D: Perthes disease 
Explanation: Amongst the given options restriction of abduction and internal rotation is seen only in Perthes disease.


About other options

In TB hip :-

i) Stage of synovitis :- Restriction of adduction, internal rotation & extension.
ii) Stage of arthritis :- Restriction of abduction, external rotation & extension.

Septic arthritis :- Restriction of adduction, internal rotation, extension in early stages.
Congenital dislocation of hip :- Restriction of abduction, external rotation.