This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Joint disorders, Subject name: Anatomy
Deformity most commonly seen in primary osteoahritis of knee joint 
Select and explain. 
A. Genu valgum, B. Genu recurratum, C. Genu varus, D. Procurvatum
C: Genu varus
Answer: C: Genu varus 
Explanation: In knee joint osteoahritis, medial joint space is affected earliest and causes assymetrical joint space narrowing This results in varus deformity Refer: maheswari 9th/e p 420