Anterior Cruciate Ligament (ACL) Injuries

What is an ACL?

The anterior cruciate ligament (ACL) is one of two cruciate ligaments that stabilise the knee joint. The knee is a mobile joint where the thigh bone (femur) meets the shin bone (tibia), with the kneecap (patella) at the front.  The ACL stabilises the knee and keeps the femur and tibia connected.


There are many ligaments in the knee.  There are four major ligaments which are the main stabilisers of the joint: the two cruciate ligaments (ACL and PCL) and two collateral ligaments (medial and lateral)

Cruciate Ligaments

Located in the middle of the knee joint, the cruciate ligaments (crossing ligaments) control the knee’s forward-backward stability. The anterior cruciate ligament is located toward the front of your knee, and the posterior ligament is located toward the back of the knee. They cross each other, hence the Latin term for ‘cross’ (cruciate) and together they stabilise the knee, preventing the tibia (shin bone) from moving forward and backwards on the femur (thigh bone).

Symptoms of an ACL tear

Most ACL injuries are sport or trauma-related. Female athletes are more likely to suffer from them than their male counterparts. This is due to anatomy: women tend to have smaller ACLs, and smaller intercondylar notches (the space where the ACL sits).  Women also typically have less muscle bulk to help stabilise the knee.


When an ACL ruptures, it is usually a very painful injury.  A popping sound and giving way of the knee might be felt.  Usually is it painful to place weight on the knee and the knee becomes quite swollen.  It may be quite difficult to walk.


An ACL tear is a major injury to the knee and is typically associated with damage to other structures within the knee joint.  These include meniscal tears, other ligament injuries (such as a medial collateral ligament injury) and damage to the cartilage surface of the knee joint. For active people it will usually mean the end of a sporting season or a period away from active exercise. 

How are ACL injuries Graded?

Like all injuries, ACL injuries are graded according to their severity or completeness of the tear.


  • Grade 1 sprains involve slight ligament damage. The ligament is stretched, but still working.
  • Grade 2 sprains are also known as partial tears. The ligament is stretched and loose and the knee may be unstable.
  • Grade 3 sprains involve a complete ligament tear, which causes an unstable knee.


Dr Ward usually sees the more severe (grade 2 and 3) injuries. These injuries are often caused by quite simple means.  They typically occur when people are running and twisting or with sporting collisions.

Treating a torn ACL

Your Physiotherapist or GP may diagnose a torn ACL from the history of the injury and a physical examination.  They will need to take an x-ray and organise an MRI scan to examine for any additional damage.


Treatment for a torn ACL depends on the patient’s expectations around activity post-recovery.  Young, active patients who want to return to agility or contact sports will often seek ACL reconstruction.  Older, less active patients may be adequately treated with a rehabilitation program.

Non-surgical treatment

A torn / ruptured ACL will not heal itself without surgery.  Adopting a less active lifestyle may be an option.


Nonsurgical options initially may involve wearing a brace then undergoing a physiotherapy program to strengthen the leg muscles. Recovery will involve reducing high-impact activities and giving up contact or agility sports (football, basketball, netball, tennis).

Surgical treatment

A torn ACL cannot be reconnected. Surgery involves reconstructing the ligament by using a tissue graft from around the knee, through an arthroscopic (keyhole) surgery.


ACL reconstruction is a minimally invasive procedure.  Dr Ward has undertaken extra training in this procedure.  Dr Ward will use a tissue graft, usually taken from your own body, either the hamstring, quadriceps or patella tendons.  He will discuss the best option for you and formulate a bespoke surgical plan.

Recovery after ACL injury

Minimally invasive arthroscopic surgery allows for the fastest recovery time.  It will however take up to 12 months to return to competitive sports after surgery.


Dr Ward will follow and supervise your rehabilitation and recommend a physiotherapy program over that period.  The aim of the rehabilitation is to restore strength and mobility and allow normal use of the knee under load.  Rehabilitation plays a critical role in restoring function after ACL injury. 


All patients, from everyday active people to recreational sportspeople and professional athletes will need to invest significant effort in their rehabilitation after ACL surgery to regain full function.  Dr Ward will speak to you about this commitment to rehabilitation prior to any surgical intervention. 

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