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What is an ACL injury?

An anterior cruciate ligament injury, commonly known as an ACL injury, is an injury to one of the knee's major ligaments. The ACL connects the tibia (shinbone) to the femur (thigh bone). In general, they occur due to sports which involve sudden changes of direction, such as football, basketball or skiing.

An ACL injury can cause pain, swelling, and make it difficult to put weight on your knee.

What causes an ACL injury?

ACL injuries typically occur during sports which put excess pressure on the knee. Actions which can cause an ACL injury during sports include: pivoting while the foot is firmly planted on the ground; suddenly changing direction; suddenly stopping; an awkward landing from a jump; and a collision or direct blow to the knee.

Ligament damage usually involves a partial or complete tissue tear, whereas a mild ACL injury may only stretch the ligament.

There are several risk factors which are understood to increase the risk of an ACL injury. These include: participating in sports known to present a higher risk of ACL injury, from football to basketball and skiing; poor muscle conditioning and previous to the same or the other knee

Symptoms of an ACL injury

The predominant symptom of an ACL injury is a pop or crack felt in the knee. Other signs to look out for include; fast swelling of the knee; severe pain; the inability to continue a sport or activity; severely inhibited movement; being very unstable or not being able to put any weight on the affected knee.

Treatment options for ACL injury

An ACL injury is typically diagnosed via a physical examination, which can involve a comparison with the uninjured knee. Your doctor may also test the function of the joint by moving it into a range of positions or asking you to perform certain actions.

Sometimes, a physical examination is all that is needed to confirm an ACL injury, although other tests are usually required, including x-rays and MRI scanning.

There are several treatment options in the immediate aftermath of a knee injury which can reduce pain and swelling. These include; rest, which is important for healing and limiting the weight which you put on your affected knee; ice, applied indirectly every two hours; compression, using a compression wrap or bandage; and elevation, for which you can use pillows to prop up the knees. You may benefit from simple analgesic pain killers such as paracetamol, or may require to see your doctor for further pain relief treatment.

Rehabilitation for ACL injury

Rehabilitative therapy is an important part of treatment for an ACL injury and can be guided by a physiotherapist who will assess and treat the condition.

Rehabilitation alone may be sufficient treatment to allow complete recovery from an ACL injury.

Further information on this condition can be found here.


Surgery for ACL injury

Surgery is typically advised when the knee remains significant unstable, or if the injury is complicated by damage to other structures within the knee. Surgery can also be recommended for athletes who wish to get back to playing their sport, or younger patients. The ACL reconstruction procedure involves the replacement of the damaged ligament and the insertion of a new ligament known as a graft. The graft is usually taken from a different part of the knee.

In certain cases, the ACL tear can be repaired. This is a specialist technique.

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