Tearing your ACL is as scary as it is painful. Tearing your ACL, like breaking a bone, usually results in a very sudden “uh oh”. Chances are as soon as your tore your ACL, you immediately knew that something was very wrong. Whether the “pop” sound gave it away or the wave of sharp pain that followed, it’s a surprising and unfortunate injury.

If you’ve just injured your ACL and are in research-mode, you’ve come to the right place. Read on as we break down the basics of ACL injury, how it happens, signs you’ve torn it, and what your prognosis and treatments are. Before we get into it, please know that this is a very treatable injury and that by investing some time into your health, you will get back to your old self.

Before we get started, let’s explain…

Where is the ACL (Anterior Cruciate Ligament)?

The anterior cruciate ligament (ACL) is one of four main ligaments that makes up the knee. The ACL and the posterior cruciate ligament (PCL) form an “X” pattern that support and stabilizes the knee, allowing for side-to-side and back-to-front motion. The ACL (making up part of the “X’ pattern) runs diagonally across the middle of the knee. The ACL connects to the thighbone (femur) and shinbone (tibia).

Why Me? Who Tears Their ACL?

If you’ve torn your ACL, chances are you’re younger. Are you a millennial? Maybe. Generation Z? Possibly. Most people that tear their ACL are between the ages of 14-35. In this demographic, women are more likely to tear their ACL. Your odds are most likely if you’re a young, female, athlete. Sorry, sporty girls!

ACL injuries are seen among “athletes in football, basketball, soccer, rugby, wrestling, gymnastics and skiing“. Sound like you?

Female athletes have a greater imbalance of muscle strength in their thighs and hamstrings. The front of the thigh is often stronger than the hamstring. The hamstring is a muscle that helps prevent the shinbone from moving too far forward which can overextend the ACL. The disparity in muscle strength between the thigh and hamstring can create the perfect environment for an ACL tear.

Why are athletes more likely to tear their ACL? ACL tears are usually caused by sudden movement changing, pivots, landing from a jump etc. These high-action, sporadic movements are most repeated by athletes. If you’re an athlete engaging in high-intensity sports (like volleyball, soccer, basketball) your odds of tearing your ACL are much higher than a gamer, chess-player, or idle office-worker.

How Does an ACL Tear Happen?

Most ACL injuries happen during team sports or other physical activity. ACLs get torn when there are sudden movement changes, quick pivots of direction, landing a jump, or if hit directly on the knee. Majority of these injuries happen without any contact from an object or another person on the field.

Here’s a cheat-sheet of how most ACL tears happen:

Slowing down and changing direction (like in a football play)

Pivoting with your foot firmly planted (like in basketball)

Landing from a jump wrong (like in volleyball)

Stopping quickly (like in baseball)

Receiving a direct blow to the knee or collision (like in hockey)

How Do I Know That I’ve Torn My ACL and Not Just Hurt My Knee?

ACL vs Hurt Knee

There are some tell-tale signs that a knee injury is specifically an ACL issue. First and foremost, you should ask yourself how the injury happened. If it was a slow onset of knee pain, decreased motion over time, and a “grinding” sort of worsening pain, it may not be an ACL tear. Almost always with an ACL injury, it’s a dramatic moment that you can trace back to.

You can sprain your ACL just like you can sprain other tendons or muscles in your knee. Tearing your ACL takes more force and is usually more severe in nature. Tearing your ACL comes with a unique set of signs and symptoms that indicate you’ve torn it.

Signs and symptoms of an ACL Tear include:

None of these signs and symptoms are isolated to just ACL tears (e.g. you could have some of these symptoms with a sprain or another injury).

An audible “pop” sound or the feeling of something “popping” in your knee.

Sudden onset of the injury.

Severe pain.

Can’t continue the activity you were engaged in.

Cannot weight bear on the affected leg.

Instability in the affected leg/ the feeling your knee is “giving out” (feeling like you’d stumble or fall if you tried to walk).

Swelling is almost immediate (within a few hours).

Poor range of motion and movement in the affected leg (can’t bend knee).

Cannot straighten the affected leg (notice when walking down stairs).

Knee may feel warm to touch (however, not always the case).

An ACL injury is almost always sudden. It’s not something that gradually gets worse. If you’ve injured your ACL, you can almost always pinpoint when it happened (which is usually during physical activity or team sport).

The Prognosis: How to Treat an ACL Tear

Like most things, the prognosis of your torn ACL depends on a few things. Mostly, it depends whether you’ve partially torn your ACL or have a complete ACL tear. You will often hear ACL injuries graded from 1-3.

The Different Grades of ACL Tears and Prognoses:

Grade 1 tear: A slight tear but joint function resumes fairly quickly. Some physical therapy, rest, icing and treatments may be required for healing.

Grade 2 tear: A partial tear. The knee joint has lost functionality. The prognosis for a partially torn ACL is good. Physical therapy will likely be required, but rehabilitation and recovery can happen within 3 months without surgical intervention. In some partial tears, surgery may be recommended.

Grade 3 tear: The ACL ligament is completely torn. There will be very little or no function of the knee. Without surgical intervention, a full recovery is not favourable. To recover and regain full range of motion and movements, (like pivoting and team sports) surgery followed by intensive physical therapy and at-home ReHab is likely. Without surgery, instability with pivoting sports will almost always continue.

When you may not need surgery after an ACL tear:

The tear is partial (Grade 1 or Grade 2 ACL tear)

You are stable on the affected leg (knee doesn’t feel like giving out).

Your knee is stable during low-impact movement (walking, stairs etc.)

Those who do not live a very active lifestyle

And most importantly: You are willing to give up high-intensity sports (e.g. soccer, football, hockey volleyball).