This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2018, Subject name: Orthopaedics
Primary osteoahritis affect all except: 
Select and explain. 
A. Hip Joint, B. Knee joint, C. Distal interphalangeal joint, D. Matacarpophalangeal joint
D: Matacarpophalangeal joint
Answer: D: Matacarpophalangeal joint 
Explanation: Osteoahritis involves DIP and PIP with sparing of MCP. Rheumatoid ahritis involves PIP and MCP with sparing of DIP. Osteoahritis commonly involves knee joint in India. Hip joint is rarely involved in osteoahritis.