So what is the ACL?

ACL is short for Anterior Cruciate Ligament. It helps to hold the knee together.

The Anterior Cruciate Ligament (ACL) is one of the two cruciate ligaments. It stabilizes the knee joint by preventing excessive forward movement of the tibia and limiting rotation.

Just injured your ACL?

Things to consider​

This page provides some background knowledge on the ACL and its injuries

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What is the role of the Anterior Cruciate Ligament (ACL) within the knee?

Your knee is the largest joint in your body, and is responsible for bearing weight, providing stability and allowing a wide range of movements.

Your knee is made up of three bones: the femur (thigh bone), the tibia (shin bone) and the patella (kneecap). The bones are cushioned by the articular cartilage and the menisci, which both act as the articular surfaces and shock absorbers between your bones.

These bones are connected by four ligaments, which are strong bands of connective tissue namely:


  • The anterior cruciate ligament (ACL) runs obliquely through the middle of your knee and is responsible for preventing your tibia from sliding out in front of your femur, as well as providing rotational stability to your knee. The ACL is unfortunately one of the most common ligaments to be injured.
  • The posterior cruciate ligament (PCL) keeps the tibia from moving backward too far. It is stronger than the ACL and is injured less often. 
  • The ligaments that prevent side to side movement of your knee are the medial collateral ligament (MCL) on the inside of your knee and the lateral collateral ligament (LCL) on the outside of your knee.

How will you know if your ACL is injured?

People experience symptoms differently; these symptoms will also vary depending on how severely your ACL has been injured and also the associated other knee injuries you may sustain in the accident.

Experiences range from feeling your knee “giving way”; hearing a snapping or popping sound; experiencing instant pain followed by swelling; a feeling of ongoing instability, pain when weight bearing; and stiffness at the knee and difficulty moving the joint in particular pain and stiffness with full flexion and extension.

A damaged ACL may involve a partial or complete tear of the ligamentous tissue. A mild injury may stretch the ligament but leave it intact. If an ACL injury is suspected, your doctor or physiotherapist will refer you for an MRI (Magnetic Resonance Imaging) scan of your knee, which will provide detailed images of inside your knee. The consultation and MRI should take place within the first few days after injury.

The MRI results will allow a doctor to determine where and how badly you have injured your knee. You may also need an X-ray to rule out any bone fracture(s).  

It’s common for multiple injuries to occur to your knee at once. As well as assessing your suspected ACL tear or rupture your doctor or physiotherapist will look for potential fractures of your femur or tibia, damage to other ligaments, any meniscal and articular cartilage injury.

Bracing with the Cross Bracing Protocol

ACL injury and healing

We consider there are 5 steps for thorough and successful healing of an ACL injury

Click on Learn More to read more detail about these 5 steps:

  1. The “Static stabilisation” of the Knee
  2. The “Functional rehabilitation of the Knee”.
  3. Erasing the Brain Injury
  4. Sport and Activity selection
  5. Ongoing surveillance and risk mitigation

What else might be injured

  1. Menisci
  2. MCL
  3. Capsule
  4. LCL
  5. Micro-fracture of bone

What is healing

  1. The bodies response from time zero
  2. Collagen
  3. Cytokines
  4. Remodelling
  5. Strength and proprioception

What we don’t know – yet.

  1. How to improve or enhance healing
  2. Can menisci heal?
  3. Diet and rehabilitation

What are your options?


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