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
[{'content': 'Deformity is most commonly seen in primary osteoarthritis of the knee joint - \nSelect and explain. \nA. Genu valgum, B. Germ recurratum, C. Genu varus, D. Procurvaturn.', 'role': 'user'}, {'content': 'Answer: C \nExplanation: In knee joint osteoarthritis, medial joint space is affected earliest and causes asymmetrical joint space narrowing. This results in varus deformity (genu varus).', 'role': 'assistant'}]