A 18 yrs old boy was palying football, when he suddenly twisted his knee on the ankle and he fell down. He got up after 10 minutes and again staed playing, but next day his knee was swollen and he could not move it. The most probable cause is-:

A i.e. Medial meniscus tear In cruciate ligament injury the findings can be somewhate perverse i.e. with a complete tear the patients may have little or no pain, whereas with a paial tear the knee is painful. Swelling also is worse with paial tears, because haemorrhage remains confined with in the joint; with complete tears ruptured capsule permits leakage and diflusion. Paial tears permit no abnormal movement, but the attempt cause pain. Complete tears permit abnormal movement which sometimes is painless.