If you play contact sports you will be familiar with an ACL tear. ACL stands for anterior cruciate ligament. It is one of four ligaments in the knee joint:
- ACL – located in the centre of the knee, prevents the tibia (shin bone) from moving too far forward.
- PCL – posterior cruciate ligament, located toward the back of the knee, prevents the tibia from moving too far backwards.
- MCL – medial collateral ligament, located on the inside of the knee, prevents the tibia from moving to the inside.
- LCL – lateral collateral ligament, located on the outside of the knee; prevents the tibia from moving to the outside.
Ligaments are robust connective tissue that joins the ends of two bones, keeping structures like joints together and stable. They are there to ensure the bones in the joint don’t move randomly but stay in place.
In the knee joint, the ACL connects the thigh bone with the shinbone, and together with the PCL, it enables the knee to move backward and forward.
What Is An ACL Tear?
An ACL tear occurs when the anterior cruciate ligament is either partly or fully torn. Most ACL tears are outright tears, meaning the ligament is fully severed. It can tear away from the femur, or the tibia, or down the centre.
How Does An ACL Tear Occur?
While ACL injuries are common in contact sports, they are not limited to athletes or sports activities. Any situation that causes the knee to bend beyond its natural range of motion can damage or tear an ACL.
An ACL tear can happen when:
- An athlete suddenly changes direction during a game
- An individual suddenly stops dead and shifts because someone cuts in front of them
- An individual lands wrong on one leg after jumping over an obstacle
- Repetitive movements, such as dance movements, cause chronic stress to the ACL
- The knee is hit directly
- Regular running on uneven surfaces like mountain trails is part of a person’s training.
- Running a person suddenly stops, causing the ACL to over-extend
- Someone lands awkwardly from a fall
- An individual carries excess weight because it weakens the knee, putting the ACL at risk.
How Do You Know That You Have An ACL Tear?
An injury to the anterior cruciate ligament is often announced by a popping sound that can be clearly heard, even by bystanders.
Other signs that your ACL is torn are as follows.
The knee caves in – The other most telling indication of an injured ACL is the unsettling sensation of the knee giving out from under you – like there’s thin air where the ground should be. This happens because the torn ligament can no longer support the knee, and it basically collapses.
The knee becomes swollen and red – The torn ligament will cause blood to rush to the area and fluids to accumulate there, causing noticeable swelling. The knee will look red and feel warm to the touch because of the increased blood flow. Because of the fluid increase, the knee may feel stiff and unmovable.
Pain sets in – Immediately after the incident, pain will set in. The pain from an ACL tear can be significant, but it is different for different people. Both the torn ligament itself and the swelling caused by the injury can cause pain. It’s common for the pain to worsen when you try to stand on the injured leg.
The range of motion is gone – With a torn ligament, the knee is no longer supported and stable. Also, the swelling makes movement difficult. You may find it difficult to walk normally and may need an assistive device to get around while the knee is healing.
The degree of these symptoms will depend on the extent of the injury and will differ from patient to patient. If the ACL is partially torn, the symptoms may be mild, but if it is completely torn, the knee will immediately feel unstable, and the person will feel unsafe on their feet.
When Should You Seek Medical Assistance?
Knee injuries can be serious because of the complex structure of the knee. If you hurt your knee and suspect that you might have a torn ACL, act quickly to reduce the swelling and inflammation by putting ice on the knee and taking NSAIDs.
If your injured knee can’t support your weight and the shape of your knee has changed, seek medical assistance without delay. You should also consult your doctor or orthopaedic surgeon in Singapore if the swelling and pain don’t subside after 48 hours.