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: Anatomy
Which joint is commonly involved in osteochondritis dissecans? 
Select and explain. 
A. Ankle joint, B. Knee joint, C. Wrist joint, D. Elbow joint
B: Knee joint
Answer: B: Knee joint 
Explanation: Kness is the most commonly affected joint. Other joints such as hip, ankle , elbow and shoulder can also be involved. Definition : * Localized condition affecting the aicular surface of a joint with separation of a segment of cailage and subchondral bone * Knee by far the most common joint involved (75% of all OCD lesions) with the ankle, elbow, wrist and other joints accounting for the remaining 25% * Most common: Lateral aspect of medial femoral condyle * Weightbearing surfaces of medial and lateral femoral condyles also affected . ref : maheswari 9th ed