The anterior cruciate ligament is one of the four major ligaments in the knee. The role of the anterior cruciate ligament is to maintain rotational stability of the knee. This ligament is vulnerable to tearing which is described as a "rupture" of the ligament. The ligament is particularly vulnerable in sports which involve sudden direction changing such as football, netball and skiing.
This ligament is under constant tension within the centre of the knee and once the ligament has ruptured it will not (unlike the collateral ligaments) heal itself.
The diagnosis of potential damage to the anterior cruciate ligament is based on your symptoms and the situation within the knee joint. Commonly patients who suffer damage to the ligament experience sudden giving way of the knee associated with a "popping" sensation when they stop and twist on the joint. This is rapidly followed by swelling in the knee and 90% of patients who have sudden swelling in the knee following a twisting injury with an inability to fully straighten the knee will have damaged their anterior cruciate ligament.
Often damage to the ligament results in a casualty attendance where x-rays are carried out which show no evidence of any bony injury. Rehabilitation of the joint with simple exercises as well as ice packs are recommended; however if the knee appears "wobbly" following such an injury and a period of rest, further investigation with an MRI scan is appropriate.
Management of anterior cruciate ligament rupture will depend both on the instability (loss of confidence) in the joint and your requirements to have a stable knee. Physiotherapy to strengthen the muscles around the joint could potentially leave you with a reliable joint; however if you wish to carry out sports which require a rotationally stable knee then reconstruction of the ligament may be the appropriate option for you.
If your knee feels unreliable on twisting following an injury which was associated with sudden swelling in the joint, Simon would recommend that an MRI scan is carried out to identify the extent of damage to both the ligaments and other structures within the knee. If the MRI scan confirms damage to the anterior cruciate ligament then Simon would suggest that you have a discussion about further treatment with a view to considering reconstruction of the ligament.