During the accident, the patient usually feels a tearing or hears a pop in the knee joint. This is followed by a rapid swelling (haemorrhage) with sharp pain and restricted movement and weight-bearing. After the acute pain has subsided, there is an unpleasant feeling of instability with an occasional sensation of the knee giving way.
The most common mechanism of injury for a cruciate ligament rupture is the combination of twisting and buckling, and occasionally overstretching the knee joint. This often results in concomitant injuries, e.g. of the medial collateral ligament or the medial meniscus. Sometimes there is a bony avulsion in the area of the tibial plateau, i.e. a strong pull on the ligament tears out a bone fragment.