Anterior Cruciate Ligament (ACL): Definition and What it is

Medically and clinically reviewed by Jonathan Lee, MD and Dylan Peterson, PT, DPT

Anterior Cruciate Ligament (ACL) Definition and Meaning

The anterior cruciate ligament (ACL) is a fibrous band of tissue in the knee joint that connects the femur (thighbone) to the tibia (shinbone). This ligament plays a pivotal role in maintaining knee function and provides stability to the knee by controlling the forward tibial movement relative to the femur (when your shinbone moves forward away from your body), preventing excessive rotation, and ensuring knee joint alignment during activities like running, jumping, and pivoting.

Anterior Cruciate Ligament (ACL) Injuries

ACL injuries are commonly associated with sports and activities that involve sudden stops, changes in direction, or high-impact collisions, like soccer, football, basketball, skiing, and gymnastics. When there is a sudden twisting or pivoting motion of the knee, there’s the potential to irritate or sprain the ACL (in which the ligament is stretched or torn). ACL injuries can occur outside of sports, like during a car accident or simply pivoting abruptly when walking. 

No matter what triggered the injury to the anterior cruciate ligament (ACL), the symptoms are generally the same, including knee pain, swelling (due to fluid buildup in the joint), reduced range of motion, and potentially difficulty walking if bearing weight on the knee is too painful or feels unstable. Some people may even experience a popping sound when the injury occurs, followed by immediate pain and swelling. 

ACL Injuries: A Hinge Health Perspective

While any sort of ligament injury can be upsetting, know this: Ligaments, including the ACL, are resilient bands of connective tissue. They’re designed to recover and heal. Still, it’s natural to feel hesitant to bear weight on an injured ACL. While many people are afraid to move after an ACL injury, maintaining range of motion through gentle exercise and movement is key. Engaging in exercises that support your healing and strengthen the affected area (plus surrounding muscles) can help prevent future injury.

Anterior Cruciate Ligament (ACL) Injury Treatment

The treatment of ACL injuries typically involves two options: non-surgical and surgical approaches. Treatment depends on the severity of the injury, as well as other factors such as your activity level and overall health. Non-surgical approaches may be recommended for mild or moderate injuries or for those who are good candidates based on lifestyle, age, and other factors. 

You may be familiar with the R.I.C.E. (rest, ice, compression, elevation) approach to healing. While there are certain elements of R.I.C.E. that are still recommended, this is actually an outdated model and experts now recommend a more updated treatment approach: P.E.A.C.E. and L.O.V.E. This framework prioritizes movement and exercise as integral to recovery in order to strengthen the surrounding muscles and provide stability to the knee. More serious ACL injuries may require surgery to reconstruct the affected tissue. 

How Physical Therapy Can Help With Anterior Cruciate Ligament (ACL) Injury

Physical therapy is a research-backed treatment for ACL injuries. Some evidence suggests that physical therapy might work as well as surgery for some patients with a torn ACL. A physical therapist (PT) can create a targeted exercise and stretching regimen that’s tailored to your symptoms and how much your ACL injury is impacting your daily life. You can see a physical therapist in person or use a program like Hinge Health to access a PT via telehealth/video visit.

How Hinge Health Can Help You 

If you have joint or muscle pain that makes it hard to move, you can get the relief you’ve been looking for with Hinge Health’s online exercise therapy program.

The best part: You don’t have to leave your home because our program is digital. That means you can easily get the care you need through our app, when and where it works for you. 

Through our program, you’ll have access to therapeutic exercises and stretches for your condition. 

Additionally, you’ll have a personal care team to guide, support, and tailor our program to you. See if you qualify for Hinge Health and confirm free coverage through your employer or benefit plan here.

This article and its contents are provided for educational and informational purposes only and do not constitute medical advice or professional services specific to you or your medical condition.


  1. Anterior Cruciate Ligament (ACL) Injury or Tear. (n.d.). John Hopkins Medicine. Retrieved from 

  2. Frobell, R. B., Roos, E. M., Roos, H. P., Ranstam, J., & Lohmander, L. S. (2010). A Randomized Trial of Treatment for Acute Anterior Cruciate Ligament Tears. New England Journal of Medicine, 363(4), 331–342. doi:10.1056/nejmoa0907797

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