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: Surgery
Joint LEAST involved in primary osteoahritis: March 2013 (b, h) 
Select and explain. 
A. Hip, B. Trapezio-metacarpal, C. Knee, D. Coraco-clavicular
D: Coraco-clavicular
Answer: D: Coraco-clavicular 
Explanation: Ans. D i.e. Coracoclavicular Osteoahritis Usually OA involves: - Hip, - Knee Does not affect MCP joint Interphalangeal joints & nodes: - DIP - Heberdens node; PIP - Bouchard nodes X-ray shows: Osteophyte formation, narrowing of joint space etc.