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
Which joint is most commonly affected in pseudogout - 
Select and explain. 
A. Knee, B. Hip, C. MP joint great toe, D. MP joint thumb
A: Knee
Answer: A: Knee 
Explanation: Ans. is 'a' i.e., Knee Pseudogout It is one of the forms of "Calcium pyrophosphate dihydrate" (CPPD) ahropathy. Pseudogout commonly involves the larger joints. Knee joint is most commonly involved; other sites are wrist, elbow, shoulder, ankle. Involvement of small joints is uncommon. Age group is > 60 yrs. In CPPD ahropathy, CPPD deposition occurs in aicular tissues. It can present in any of the following three forms :? 1) Asympatomatic chondrocalcinosis 2) Acute synovitis - Pseudogout 3) Chronic pyrophosphate ahropathy The radiologic hallmark of CPPD is "chondrocalcinosis. Chondrocalcinosis is seen as punctate and/or linear radiodense deposits in fibrocailaginous joint menisci or aicular hyaline cailage. Definitive diagnosis is made by synol fluid polarised light microscopy which shows weakly positive, birefringent, rhomboid crystals of CPPD.