Australia has the highest reported rates of anterior cruciate ligament (ACL) injury in the world, and the rate has risen 70 per cent in under 25s over the last 15 years. In males, the peak incidence in 2014–15 was for 20–24-year-olds; for females, it was for 15–19-year-olds. (Medical Journal of Australia)

Whether you’ve experienced an ACL injury or want to learn more about the causes, prevention and management, this blog will outline everything you need to know.


What Is an ACL

The Anterior Cruciate Ligament (ACL) is the most important stabilising ligament in your knee. The prime function of the ACL is to prevent forward translation (gliding movement) and excessive rotation of the tibia (shin bone) on the Femur (thigh bone).

ACL injury Causes
There are three main causes of an ACL injury


  1. A valgus movement in the knee. This is when the knee undergoes a rotational force while slightly bent with the foot planted on the ground causing the knee to bend inwards

  1. Change of direction, cutting, pivoting- getting tackled/pushed can put you in this position that we sometimes call the “point of no return”
  2. The least common cause is when the knee experiences a hyperextension (bends backwards) movement while the foot is planted on the ground.


Our physios can run a full biomechanical assessment of your movement strategies to help identify any predisposing biomechanical issues you may have, thus helping to reduce stress on your ACL during your activities.


Grading an ACL injury

Accurately diagnosing the severity of an ACL injury is most important. Not all ACL injuries require surgery but a detailed and specific rehabilitation programme is of utmost importance. At JBS Physio we use both evidence-based assessment methods and our experience treating numerous ACL injuries, to accurately diagnose assess and manage the injury according to its grade. A carefully managed and executed rehab programme is essential for return to sport/activity. At JBS Physio we make sure this plan is executed to help you return safely to activity.

There are three grades of an ACL injury, each describing the integrity of the ACL ligament following the injury. Although an ACL injury can be graded, no two people will have exactly the same rehab program- it’s about catering rehab to YOUR specific needs and goals.

  • Grade 1 injuries indicate mild damage where the ACL may have been stretched but still provides adequate stability to the knee joint.
  • Grade 2 ACL injuries are rare and describe an ACL that is stretched and partially torn.
  • Grade 3 ACL tears are the most severe of ACL injuries. This is a complete or near complete tear where the ACL is no longer providing stability to the knee joint.


Risk Factors for an ACL injury

  • Females are 3x more likely to tear their ACL than males for the following reasons:
    • The anatomical alignment in the female knees due to wider pelvis results in increased valgus forces on the knees
    • Hormonal changes in females cause increased laxity in ligaments around the body causing joints to become less stable
  • Participating in the following sports which involve jumping and landing, cutting movements and physical contact from opposing players:
    • Soccer
    • Rugby
    • AFL
    • Basketball
    • Volleyball
    • Gymnastics
    • Skiing
  • Poor physical conditioning where strength is lacking not only in the knee joint but also around the hip and ankle, places increased stress around the knee joints when participating in sports and activities of daily living
  • Poor biomechanics during sports/exercise and activities of daily living can predispose to increased stress on the ACL during certain movement patterns., such as moving the knees inward or rolling the ankle inwards during a squat, landing or sit-to-stand places increase stress on the ACL.
  • Playing on artificial/synthetic turf

If you think you might be at risk of an ACL injury based on these risk factors it’s not a sign to stop participating in the sports you love, or to be overly cautious. Instead, the research shows us that preventative programs are the best way to reduce these injuries.

We at JBS physio can teach you neuromuscular agility training programs which have been shown to reduce ACL injuries by 50–80%.

Symptoms following an ACL injury

  • A loud “pop” noise/sensation at the onset of the injury
  • Severe instability in the injured knee
  • Rapid swelling around the knee joint (within 0-4 hours)
  • Pain with weight bearing and general knee range of motion
  • Reduced range of motion due to swelling

Management of an ACL injury

At JBS Physio, we assess and treat many ACL injuries successfully. One of our highly skilled and qualified Physiotherapists will be able to assess the severity of the ACL injury and plan your individualised rehabilitation while providing advice on your injury management.

When injuring the ACL, there is a chance that supporting structures of the knee (other ligaments and/or the menisci) may have also been injured. It may be important for you to have some imaging to assess the extent if the injury.

If surgery is required it is highly recommended that you complete a pre-operative rehabilitation (prehab) prior to your ACL reconstruction surgery. Prehab has been shown to improve neuromuscular and self-reported knee function as well as optimising return to sport post ACL reconstruction surgery.

If you meet the criteria for surgical intervention of your torn ACL the surgeon will replace the torn ACL with a graft of their preference (most likely Hamstring or Patella tendon). Following the surgery, the Physiotherapist will use the surgeon’s postoperative protocol and the current evidence-based ACL rehabilitation guidelines specific to you and your surgical approach.

The rehabilitation following an ACL reconstruction surgery is a minimum of 9 months which is how long it takes for the graft to form into a strong and effective ligament. Returning to the sport prior to 9 months results in a higher chance of re-rupture of the ACL possibly requiring another surgical intervention.

If returning to sport is of high priority to your come to speak to one of our Physiotherapists who will help you return to your pre-injury levels as soon as possible.