ACL Tears: Risk Factors, Symptoms & Treatment

Each year, between 100,000 and 200,000 ACL tears occur in the United States alone. While many people tend to associate this type of injury with athletes, you don’t have to be an athlete to tear your ACL. For that reason, it’s important to understand this injury and how to prevent it, no matter your skill level.

In this guide, we’ll explain how ACL tears occur and how to prevent them, who is most at risk, the signs and symptoms of an ACL tear, and what treatment options are currently available.

What is the ACL?

The anterior cruciate ligament, more commonly known as the ACL, is a crucial stabilizing ligament in the knee.

  • Anterior means “in front”. When used to describe human anatomy, anterior means “toward the front of the body”. The ACL is actually located in the center of the knee, but its purpose is to prevent the shin bone (tibia) from sliding out in front of the thigh bone (femur).
  • Cruciate means “cross-shaped”. Together, the ACL and PCL (posterior cruciate ligament), form the shape of a cross.
  • Lastly, a ligament is a strong band of tissue that connects one bone to another. The ACL is one of four ligaments that connect the femur to the tibia.

What are ACL Tears?

An ACL tear occurs when the ligament is stretched so far beyond its normal range that it tears.

A complete tear is the most severe type of ACL injury, but it’s not the only type. Doctors classify ACL injuries into three grades of severity, ranging from Grade I to Grade III.

  • Grade I: Minor ligament trauma. The ACL’s fibers are stretched, but not torn – this is also referred to as an ACL sprain.
  • Grade II: Moderate ligament trauma. Some of the ACL’s fibers are torn, but not all – this is also referred to as a partial tear.
  • Grade III: Severe ligament trauma. The ACL has separated completely and so it’s referred to as a complete tear.

torn acl diagram orthopedic surgeon dr domby tampa fl

How does an ACL tear happen?

Most ACL tears are “no-contact” injuries, meaning that instead of being caused by a tackle or fall, they’re caused by a sudden movement of the knee. Awkward landings, twisting, and pivoting are the most common movements that cause this type of injury.


Risk Factors for ACL Tears


While an ACL tear can affect anyone of any age, they are most common among people between the ages of 15 and 45. People in this age range are more likely to participate in the types of activities that frequently cause ACL tears, such as competitive sports.


ACL injuries are two to eight times more likely to occur in women. While the exact reason for this is still up for debate, researchers suspect that it is multifactorial including anatomic differences.


Participating in sports or activities that require you to pivot, twist, or jump can increase your risk of an ACL injury. The most high-risk sports are as follows:

  • Basketball
  • Soccer
  • Football
  • Lacrosse
  • Volleyball
  • Softball/Baseball
  • Wrestling
  • Skiing
  • Running

Tips for preventing an ACL tear

If you fall into any of the above increased-risk categories, knowing how to prevent an ACL injury is especially important.

Whether you play a competitive sport or enjoy an athletic hobby, no one wants to be sidelined by an ACL sprain or tear. Here are some tips you can use to reduce your risk of injury.

  • ACL prevention programs. There are multiple programs that are found to be helpful in preventing an ACL tear. Talk with your doctor to learn more about these programs.
  • Don’t forget to stretch. Before any game or workout, it’s important to stretch and loosen up any areas that may be tight. Squats, lunges, and single-leg stances are all great for improving your center of balance and improving the flexibility of your knees.
  • Practice proper landing techniques. If you play a sport like basketball that involves a lot of jumping, it’s important to be mindful of your form as you land. Practice jumping and landing softly with your knees bent, chest high, and buttocks back. Do this in front of a mirror or with someone watching you so that they can make sure your form is correct.
  • Keep your ligaments healthy and strong. Lastly, don’t underestimate the importance of staying hydrated and eating a balanced diet. Keep your ligaments as healthy and functional as possible by making sure your diet includes enough protein, vitamin C, and vitamin A.

Signs & Symptoms

The signs of an ACL tear can vary from person to person, but the most common symptoms are sudden onset of pain and swelling in the knee.

Additional signs of an ACL tear include:

  • A loud “popping” sound or sensation in the knee
  • Pain or soreness around the knee joint
  • Swelling around the knee within the first 24 hours of injury
  • Feeling unstable when you walk
  • Feeling like your knee joint is “loose”
  • Smaller range of motion – you can’t bend and flex your knee like you usually can

Some athletes know that they’ve torn their ACL right away by the distinctive “pop” sound it makes. Other times, it can be hard to tell the symptoms of a torn ACL from a torn meniscus or another knee injury – you’ll need to see a doctor to get an accurate diagnosis.

How is an ACL Tear Diagnosed?


A torn ACL can be diagnosed with a series of simple tests. The most common of these is called the Lachman test. While the patient is lying down, the doctor bends the knee at a 15 to 20-degree angle and stabilizes the thigh bone (femur). With the thigh bone held in place, the doctor then pulls the shin bone (tibia) forward and feels whether the endpoint is “firm” or “soft”. A soft endpoint can be described as feeling loose.

Your doctor will likely perform these types of tests on both legs for the sake of comparison.


Soft tissue, like ligaments and tendons, don’t appear on x-rays. However, depending on the nature of your injury (contact vs no-contact), your doctor may want to rule out broken bones.

MRI Scan

If your doctor suspects that you’ve injured your ACL, they’ll perform an MRI scan to confirm the diagnosis and more accurately assess the severity of the tear.

ACL Tear Treatment Options

Immediately following an ACL injury, proper first-aid care can go a long way to reduce pain and swelling. Remember the acronym R.I.C.E., which stands for:

  • Rest: Pause all sports and activities and stay off your feet as much as possible until you’re able to see a doctor.
  • Ice: Try to ice your knee for 20 minutes every two or three hours during the first 24 to 48 hours of your injury. Never apply ice directly to your skin – use an ice pack or wrap up ice in a light cotton t-shirt or towel to prevent frostbite.
  • Compression: Wrap your injured knee with a compression wrap or elastic bandage.
  • Elevate: Keep your injured leg propped up on pillows so that it’s above the level of your heart. This helps to drain fluid away from the knee and reduce swelling.

Unfortunately, a complete ACL tear is almost always a season-ender for athletes. But it doesn’t have to be a career-ender – recent advances in sports medicine mean that many athletes are able to make a full recovery.

Non-Surgical Treatments

Not all ACL injuries require surgery. Minor sprains and partial tears can often be treated using a combination of the following non-surgical methods.

  • Physical therapy. A physical therapy treatment plan helps patients strengthen the muscles around the knee, decrease pain, and improve knee mobility. If your doctor recommends using crutches, physical therapy can help you learn how to use them properly and transition back to walking without them.  Physical therapy requires patients to be active participants in their own treatment. That means regularly attending therapy sessions and even performing daily exercises at home.
  • Knee braces. A brace helps to prevent the knee from moving beyond its normal range of motion. It also provides extra support and stabilization.
  • Medication. Anti-inflammatory medications are often recommended to help reduce swelling following an ACL injury. For chronic knee pain, some doctors may prescribe opioids.

If the treatments above are unsuccessful and the knee continues to buckle due to instability, your doctor may recommend surgical treatment.

Surgical Treatments

jogging acl injury dr domby orthopedic surgeon tampa fl

For severe ACL tears, your doctor may recommend surgery to repair or reconstruct the ligament.

Ligament reconstruction surgery is a minimally invasive procedure performed by an orthopaedic surgeon that involves several small incisions and a small camera called an arthroscope. A new ligament is made from a tendon. Discuss with your doctor to determine the right procedure for you.

Before surgery, your doctor will likely recommend several weeks of physical therapy to help reduce swelling and strengthen the muscles around the knee. If you were to go into surgery with a stiff and swollen knee, you may not be able to restore your knee’s full range of motion afterward.

During surgery, you can expect your doctor to use a general anesthesia to reduce your pain and discomfort. Your surgeon will then remove the damaged ligament and replace it with a tissue graft from a tendon (a type of fibrous connective tissue that attaches muscles to bones).

The graft is secured to your thigh and shin bones using small screws or other fixation devices and acts as a “bridge” for new ligament tissue to grow on.

Following surgery, your doctor will typically recommend physical or occupational therapy to help your knee regain full mobility. It takes time for the ligament to regrow, but with this combination of advanced surgical techniques and noninvasive treatments, most patients are able to recover from a torn ACL in seven to nine months.

However, keep in mind that the recovery process is different for everyone, and not everyone’s goals are the same. For example, someone whose goal is to start jogging again is going to have a shorter recovery time than someone whose goal is to return to a competitive sport.

Have Questions? Ask Your Orthopaedic Surgeon

As a former Division I college soccer player and lifelong athlete, Dr. Brian Domby is able to approach sports injuries from a unique perspective.

Dr. Domby is a team physician for various athletes and teams, including:

  • Tampa Bay Lightning Hockey – since 2013
  • USA Women’s Hockey
  • US Figureskating

Want to know more about diagnosing and treating ACL tears and other sports injuries? Call 813-979-0440 or visit Dr. Domby’s website to talk with a knowledgeable orthopaedic surgeon. Or, make an appointment at one of his office locations in Tampa or Wesley Chapel, Florida.


Orthopaedics, Sports Medicine & Spine

About this author.


Brian C. Domby, MD

Orthopaedic Surgery & Sports Medicine, Knee & Shoulder

  • Accepting new patients

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