An overview of ACL injuries

The anterior cruciate ligament (ACL) is one of the major ligaments in the knee that connects the femur (thigh bone) to the tibia (shin bone). The ACL has a very important role in knee stability as well as helping to control forward-backward movements and twisting of the lower leg. This control and stability are very important in helping to protect and preserve the health of the knee joint and cartilage as well as to help prevent the early development of osteoarthritis (OA). The ACL is helped in its role by many other structures around the knee. Namely; the menisci (cartilage), muscles (quadriceps, hamstrings and calves), and other supporting ligaments around the knee.


ACL injuries are one of the most common types of knee injury and can have a significant impact on quality of life, especially early on following injury. The ACL is most commonly injured in high impact and fast-paced sports such as skiing, netball, football and rugby. Common causes for ACL injury can be contact or non-contact injuries. Contact injuries include tackling collisions during contact sports such as rugby and football while non-contact injuries can happen following a bad landing from a jump or a sudden change of direction. It is not only sportspeople that can injure their ACL and injuries can occur in non-sporting injuries such as falls or sudden twisting of the knee.

ACL injuries are more commonly seen in people between the ages of fifteen to forty-five as this is the age range where people are generally more active. They are also more common in women, with women being two to ten times more likely to injure their ACL’s than men. This is thought to be due to differences in anatomy; biomechanics, or differences in movement patterns and hormones.

The ACL can either be partially or completely torn and can happen in isolation or in combination with injuries to the other ligaments, cartilage or bone. These injuries can be managed conservatively with rehabilitation, but the majority of complete ACL injuries are treated with keyhole surgery (arthroscopic ligament reconstruction) and a comprehensive rehabilitation program.

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How do I know if I have injured my ACL?

There are a number of signs or symptoms that might lead to you suspecting that you have an ACL injury. Firstly, the mechanism of injury or way that the injury happened can be considered. A twisting or over-extending movement to the knee are likely to injure the ACL. Secondly, there might be a popping sound or sensation at the time of injury. There will often be severe, activity-limiting pain.

Following an ACL injury there will be a rapid swelling response and a considerable loss of knee movement that can last for a few weeks. The knee might also feel painful and unstable when walking and could “give way” or collapse when bearing all of your weight. There usually isn’t much bruising following an ACL injury, but it can be present if there is an injury to other ligaments or muscles around the knee.

If an ACL injury is suspected then it is important to make an appointment to see a qualified clinician who is experienced in assessing musculoskeletal injuries. This may be a GP, physiotherapist, sports medicine consultant or orthopaedic surgeon. At Circle Health we are able to offer short notice appointments with all of these specialties. Our clinicians will then take a thorough history and perform a physical assessment of the knee to help them to develop a potential diagnosis and determine the best course of treatment. It is common to be referred on to see an orthopaedic specialist if an ACL injury is suspected. Orthopaedic specialists are surgeons that deal with injuries to joints, ligaments, muscles and bones.

What to do next following an ACL injury

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