Anterior Cruciate Ligament (ACL) injuries

What is the ACL?

Ligaments are tough, non-stretchy fibres that hold your bones together. The ACL is one of four primary ligaments that connect your thigh bone (femur) to your shin bone (tibia) at the knee. The ACL gives your knee stability by limiting side-to-side rotation and preventing the tibia from moving ahead of the femur. As well as ligaments, your knees also contain a cushion of articular cartilage that caps the ends of each leg bone, plus additional shock-absorbing cartilage called the meniscus, between them. 

How ACL injury can happen

Injury to the ACL is one of the most common knee ligament injuries. It can tear if it’s stretched beyond its normal range. This can happen when your legs make sudden twisting movements, such as when slowing down from running, or landing from a jump. You may hear a ‘pop’ when it happens, and your knee may give way and begin to swell and hurt. 

What can you do about it?

Ligaments, unlike muscles, don’t have their own blood supply, so your ACL can’t heal itself. It can be surgically replaced, and many professional sportspeople choose this if they injure it, while less active people can treat a torn ligament with arehabilitationprogram that focuses on strengthening specific muscles and changing lifestyle. If you suffer an ACL injury, your doctor can discuss the different treatment options with you and help choose the one that’sright for you.

What are the symptoms of an ACL injury?

You may hear a popping sound if you injure your ACL, followed by sharp pain and significant swelling of the knee, so chances are you’ll seek medical help straight away and have it diagnosed. Other symptoms include much-reduced knee movement, and not being able to move your knee normally, or walk without pain or instability. As well as examining your knee in specific positions and manipulating its movement, your doctor will probably arrange X-rays to check for fractures, or an MRI scan.

How is an ACL injury treated?

Your doctor may recommend a range of treatment options, depending on your specific symptoms and the severity of your injury. He or she will also discuss with you how the injury is affecting your lifestyle and your favourite activities and sports. Treatments can include:

  • Knee brace – a temporary measure to improve your knee’s stability while you and your doctor determine the extent of your injury and the appropriate treatment.
  • Pain relief – anti-inflammatory medication like aspirin or ibuprofen, and cooling packs to reduce inflammation and pain in the knee.
  • Physiotherapy – if you have only a partial ACL tear, your knee is stable during routine activities, and you avoid any high-risk sports and activities, physiotherapy can help you reduce pain and increase mobility.
  • Surgery to repair the tear – if you’re still in pain after trying other treatments, your doctor may suggest surgery to repair the tear, help relieve pain and restore your mobility. Most ACL repairs involve surgical reconstruction, which involves replacing the ACL with another tendon from your body. This can now be done with less invasive, arthroscopic surgery, using a fibre-optic scope through a small incision.

After surgery, you can usually return home the same day. You may have to wear a splint or brace for a while to help the healing process, and many people use crutches for the first few weeks following the operation. Full recovery can take up to a year, and rehabilitative physiotherapy can require six to nine months. Your doctor will discuss with how soon after surgery you can start participating in routine, and then more demanding, activities.

Next Steps

Contact your GP or health professional to discuss your options