If you tear your anterior cruciate ligament, you may have the sensation of your knee giving out or buckling. You may even hear a popping sound. Your knee joint will start to swell. This happens because the small blood vessels in the ligament also tear and leak blood into the joint.
The pain resulting from a torn anterior cruciate ligament varies widely. The anterior cruciate ligament itself has no pain receptors. But the movement that causes the ligament to tear often causes damage to other parts of the knee that do have pain receptors. Some people are unable to walk. Others may feel they can play through the injury. Your knee often feels as though it will give way or easily bend backward.
Causes and Risk Factors
Quick changes of direction while running cause most anterior cruciate ligament injuries. When a basketball player running down the court plants his foot hard to change direction, his knee buckles as the thighbone and shinbone move in opposite directions, tearing the anterior cruciate ligament.
Basketball, soccer and skiing often cause anterior cruciate ligament injuries. Football players have the greatest risk for multiple knee injuries like combined anterior cruciate ligament, medial cruciate ligament and cartilage damage.