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: Orthopaedics
Which one of the following tests will you adopt while examining a knee joint where you suspect an old tear of anterior cruciate ligament - 
Select and explain. 
A. Posterior drawer test, B. Mc Murray test, C. Lachman test, D. Pivot shift test
C: Lachman test
Answer: C: Lachman test 
Explanation: Lachman's test is the most sensitive test for anterior cruciate ligament tears.
It is done with the knee flexed at 20 degrees. So it can be done in acute as well as chronic injuries. (because in acute cases with hemarthrosis more flexion is usually not possible so performing anterior drawer test is difficult).