ACL Rupture

What is the ACL?

The anterior cruciate ligament (ACL) is a ligament in the middle of the knee that is very important in providing stability to the knee, especially in twisting movements.

How is it ruptured?

The ACL is often ruptured during a pivoting or twisting movement, usually while playing sport. It can also be caused by a blow to the outside of the knee when the knee is bent. Sometimes, it is caused by hyper-extending (over straightening) the knee, such as when jumping up and landing awkwardly.

What problems does an ACL rupture cause?

When the ACL ruptures, there is often sudden pain and the knee gives way. The knee typically swells significantly. The pain and swelling typically take a few weeks to resolve.

The main problem that an ACL rupture causes is instability of the knee. If you are lucky, the ACL may heal well enough that it does not cause significant problems, especially if you do not play sport. Often, however, the knee may feel unstable or give way with twisting movements during sport or, in the worst cases, even when doing day to day activities.

Long term, if the knee is unstable, there is an increased risk of further injury to the cartilage within the knee and also arthritis.

How is an ACL rupture treated?

Immediately after a significant knee injury like an ACL rupture, applying ice to the knee is important, as it minimises swelling. Resting and elevating the knee are helpful and a period mobilising with crutches may be necessary.

Early review by an Orthopaedic Surgeon is recommended so that the knee can be assessed. Sometimes there may be other ligament or cartilage injuries that may also be present. An MRI scan is helpful in confirming the extent of the injuries. Physiotherapy should be commenced as early as possible to reduce swelling and regain muscle strength and range of motion at the knee.

Depending on your circumstances and the stability of the knee, the ACL rupture may be treated surgically or non-surgically.

Non-surgical treatment involves rehabilitating the knee and gradually returning to full activities. If you are able to return to all of your normal activities and the knee does not feel unstable, no further treatment is necessary. If the knee is unstable or you wish to return to sports that involve a lot of twisting and pivoting or contact sports, non-surgical treatment is less likely to be successful. In that case, an ACL reconstruction is recommended.