Photograph of a woman runner holding their knee due to ACL injury

ACL Injuries: Causes, Symptoms & Treatments

Kerrie-Ann Bernard Knee pain, Limb pain, Pain


We’ve all heard a story about someone tearing their ACL or have seen it happen in professional sports. That’s not surprising when you consider that nearly 250,000 ACL injuries occur in Canada and the United States each year. But what does it really mean to injure or tear your ACL? Today we’ll discuss ACL anatomy, injury causes, symptoms, and available treatments.

ACL Anatomy: What is the ACL?

The ACL or the anterior cruciate ligament is a tough fibrous band located in the knee that prevents the excessive forward movement of the shinbone on the thigh bone. The ACL is one of two crossing ligaments located in the centre of the knee, the other being the MCL or medial collateral ligament. Together the ACL and MCL stabilize the knee joint.

Illustration of knee anatomy showing the location of the Anterior Cruciate Ligament or ACL
Fun Fact: Anterior cruciate ligament translates to front crossing ligament, and posterior cruciate ligament translates to behind crossing ligament, noting where the ligaments are located within the knee.




ACL Injury Causes

ACL injury is common in athletes that participate in high impact sports such as soccer, tennis, skiing, basketball, and football. ACL injuries are often the result of a sudden change in direction, pivoting, sudden stopping, or jumping. But, there are two main ways you can injure your ACL, they are called “categories” and are:

  • Physical contact: The ACL can be sprained or torn when there is a direct blow to the outside part of the knee when the foot is firmly planted on the ground. This accounts for 30% of ACL injuries.
  • Non-contact injuries: This is the most common cause of an ACL injury. It can occur following a quick deceleration, a sudden change in direction, or awkwardly landing on the knee. This accounts for 70% of all ACL injuries and is the is the more common way of injuring your ACL.

ACL Injury Signs and Symptoms

Side view illustration of knee anatomy showing a complete tear of the ACL
Not sure if you’ve torn or sprained your ACL? There are common signs and symptoms to look for. Although everybody is different you may have sprained, hurt, damaged, injured, or torn your ACL if you experience any of the following:

  • Hearing a ‘pop’ during the injury
  • Sudden onset of knee pain
  • Immediate swelling
  • Tenderness over the tip of the shin bone
  • Limited knee range of motion
  • A feeling of instability or looseness in the knee

Did you know? Female athletes have 4-8 times greater risk of ACL injury compared to their male counterparts and account for the majority of ACL injuries.

ACL injury Treatments

When the ACL is sprained or torn, it has a tough time stabilizing the knee during movement. Some ACL injuries do require reconstructive surgery, especially for patients who wish to return to playing sports at a competitive level. Physiotherapy can help both pre and post op to ensure a successful recovery.

When surgery is not needed, an effective exercise plan designed for you by a qualified physiotherapist can rehabilitate your knee back to normal levels of function. Every person is different, but the goal of ACL physiotherapy is to increase the range of motion of the knee, strengthen the muscles around the knee, and improve balance. Depending on your unique needs your physiotherapist may use any of the following treatments:

  • Strengthening and stretching exercises
  • Balance exercises
  • Manual therapy
  • Patient Education

Remember that this information should be used as a tool to help you make an informed decision of whether or not you should see a physiotherapist. If you think you may have injured your ACL, we recommend seeking an assessment by a qualified physiotherapist. Find a clinic near you.

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