This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Rheumatoid Arthritis, Subject name: Orthopaedics
Which joint is spared in Rheumatoid arthritis 
Select and explain. 
A. MP joints of hand., B. DIP joints of finger, C. PIP joints of finger, D. Atlanto-axial joint
B: DIP joints of finger
Answer: B: DIP joints of finger 
Explanation: Ans. is 'b' i.e. DIP joints of finger. DIP joint is characteristically spared in RA.Joint most commonly involved in RA Metacarpophalangeal joints especially of index finger.