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
All the following are causes of a painful limp except- 
Select and explain. 
A. Slipped femoral epiphysis, B. TB of the hip, C. Perthes disease, D. Infantile Coxa Vara
D: Infantile Coxa Vara
Answer: D: Infantile Coxa Vara 
Explanation: Infantile (congenital) coxa vara causes painless limp.