Anterior Cruciate Ligament (ACL)

Anterior Cruciate Ligament (ACL) is a ligament in the knee that is commonly injured with change of direction sports. This ligament has a very important role in the knee to provide stability. If injured rehabilitation needs to be comprehensive in order to get players back to their sport.

“I’ve done my ACL” is a sentence all change-of-direction athletes dread. The ACL is a ligament in the knee that is commonly injured with change of direction sports such as netball, football and basketball, or from direct trauma to the knee. If completely torn the rehabilitation is extensive, taking at least 9-12 months before return to sport. Both surgical and non-surgical approaches are considered based on the injury.

The ACL attaches the femur to the tibia in the middle of the knee joint and prevents the tibia (shin) from moving anteriorly (in front) of the femur. The ACL can be torn from direct or indirect contact injuries. Noncontact injuries are far more common, accounting for 75% of ACL injuries. This is often through change of direction movements where the foot remains planted, pivoting, twisting and landing. Females are more likely to sustain ACL injuries than males due to ligament laxity and a wider pelvis creating different forces throughout the knee.

How do you know if you have torn your ACL?

Often if the ACL is torn there will be a popping sound heard at the time of injury. It is initially quite painful and the knee will get lots of swelling quickly. Due to this swelling and pain there will be a loss of knee range of motion. Lastly there often is a feeling of instability in the knee afterwards.

It is important if you are experiencing these symptoms to see a health professional such as a physiotherapist for an assessment. The assessment will consist of range of motion testing, strength testing, and ligament testing to determine if the ACL has been ruptured or if any other structures have been injured in the process. If your health professional suspects that the ACL has been injured, you will be referred for an MRI of the knee. Given the long nature of an ACL recovery and the potential need for surgery, it is important to confirm any injury on imaging.


Surgical and nonsurgical treatments will be considered depending on the extent of the injury, any other damage done to the knee, and the goals and activities that the patient wishes to return to.

Non-surgical is often considered if there isn’t a full tear or if the patient is not going to be continuing change of direction activities. In saying that, even with a nonsurgical approach there is full capacity to return to change of direction sports if the player wishes to. This is done by ensuring the structures surrounding the knee provide enough strength to support the knee and the loads it is placed under.

Surgical treatment is often considered when wishing to return to high level change of direction sports. Surgical repair consists of repairing the ACL with a tendon graft, often taken from the hamstring or quadriceps.

Both conservative and surgical treatment options require extensive rehabilitation before returning to sport. The initial stages will be focused on regaining full range of motion and reducing swelling. Then strength training will begin, and the knee will be gradually loaded. After these strength changes have occurred, and testing is passed, agility training can be incorporated into the routine. This will continue to be progressed over time before returning to sport 9-12 months after the initial injury or surgery. This rehabilitation must be taken seriously due to high reinjury rates.

Due to the long nature of recovering from this injury, good support systems must be in place. It can be very frustrating to be taken away from one sport for so long, so finding activities that the player can participate in safely is really important.

Although ACL tears consist of a long recovery, it is entirely possible to return back to the same level of sport.