ACL Tears Signs and Symptoms

What you need to know

The anterior cruciate ligament, or ACL, is one of four major knee ligaments. The ACL is critical to knee stability, and people who injure their ACL often complain of symptoms of their knee giving out from under them. Therefore, many patients who sustain an ACL tear opt to have surgical treatment for this injury.

What is the ACL?

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ACL injuries occur when there is damage to one of the major ligaments of the knee. J. M. Horrillo / Getty Images

The anterior cruciate ligament, also called the ACL, is one of the four major ligaments of the knee. The ACL prevents excessive motion of the knee joint--patients who sustain an injury to their ACL may complain of symptoms of the knee "giving out."


How does an ACL tear occur?

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ACL tears are often sports-related injuries. Getty Images / Alexa Miller

An ACL tear is most often a sports-related injury. ACL tears can also occur during rough play, mover vehicle collisions, falls, and work-related injuries. About 80% of sports-related ACL tears are "non-contact" injuries. This means that the injury occurs without the contact of another athlete, such as a tackle in football. Most often ACL tears occur when pivoting or landing from a jump. The knee gives-out from under the athlete when the ACL is torn.

Signs of an ACL Tear

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Learn the common symptoms of an ACL tear. Courtney Keating / Getty Images

The diagnosis of an ACL tear is made by several methods. Patients who have an ACL tear often have sustained an injury to the knee. The injury is often sports-related. They may have felt a "pop" in their knee, and the knee usually gives-out from under them.

ACL tears cause knee swelling and pain. On examination, your doctor can look for signs of instability of the knee. These special tests place stress on the ACL, and can detect a torn ligament.

An MRI may also be used to determine if the ligament is torn, and also to look for signs of any associated injuries in the knee.


Is Surgery Necessary?

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ACL reconstruction is the usual treatment of a torn ACL. Javier Larrea / Getty Images

ACL tears do not necessarily require surgery. There are several important factors to consider before undergoing ACL surgery. First, do you regularly perform activities that normally require a functional ACL? Second, do you experience knee instability? If you don't do sports that require an ACL, and you don't have an unstable knee, then you may not need ACL surgery.

The is also a debate about how to treat a partial ACL tear. If the ACL is not completely torn, then ACL reconstruction surgery may not be necessary.

Many patients with an ACL tear start to feel better within a few weeks of the injury. These individuals may feel as though their knee is normal again, but the problems with instability may persist.


Surgery for an ACL Tear

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Learn about surgery for an ACL tear. Thierry Dosogne / Getty Images

The usual surgery for an ACL tear is called an ACL reconstruction. A repair of the ligament is rarely a possibility, and thus the ligament is reconstructed using another tendon or ligament to substitute for the torn ligament.

The are several options for how to perform ACL surgery. The most significant choice is the type of graft used to reconstruct the torn ACL. There are also variations in the procedure, such as the new 'double-bundle' ACL reconstruction.

Risks of ACL surgery include infection, persistent instability and pain, stiffness, and difficulty returning to your previous level of activity. The good news is that better than 90% of patients have no complications with ACL surgery.


Post-Surgical Rehab

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Physical therapy is a critical part of ACL recovery. DNY59 / Getty Images

Rehab is one of the most important, yet too often neglected, aspect of ACL reconstruction surgery. Rehab following ACL surgery focuses on restoring motion and strength, and improving the stability of the joint to prevent future injuries.

While general guidelines exist for ACL rehab, it is critically important that each individual progress through their rehab as their knee allows. Progressing too quickly or too slowly can be detrimental to overall results from surgery, therefore it is important to ensure your therapist and physician are guiding your rehab.


Braces for ACL Tears

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Brace use is controversial after ACL tears. Alexander Klemm / Getty Images

Many patients are given a knee brace after ACL reconstruction surgery. How necessary are the knee braces used after ACL reconstruction? What if I didn't get a knee brace after ACL reconstruction, should I be wearing a knee brace?


Sports & ACL Tears

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Sports injuries commonly involve the ACL. Thomas Barwick / Getty Images

Athletes often have particular difficulty once they have sustained an ACL injury. Many sports require a functioning ACL to perform common maneuvers such as cutting, pivoting, and sudden turns. These high demand sports include football, soccer, basketball, and others. Patients may be able to function in their normal daily activities without a normal ACL, but these high-demand sports may prove difficult. Therefore, athletes are often faced with the decision to undergo surgery in order to return to their previous level of competition.

ACL tears are often seen in high profile athletes. Recent athletes who have sustained ACL tears include football player Tom Brady, golfer Tiger Woods, and soccer player Frankie Hejduk.


ACL Tears in Kids

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Children can injure their ACL too. Hero Images / Getty Images

ACL reconstruction surgery is the standard treatment for young, active people who sustain an ACL tear. But what happens when that person is a child? Should ACL surgery be delayed until the child is older, or should ACL reconstruction be performed before skeletal maturity?

The concern of performing ACL surgery in children is that there is a risk of causing a growth disturbance in growing children. Growth plate problems as a result of ACL surgery could potentially lead to early growth plate closure or alignment deformities. However, recent research is showing that the risk of growth plate problems is much less then the risk of permanent knee damage if the ACL is not fixed.


ACL Tears in Women

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Women are at higher risk of injuring their ACL. Corey Jenkins / Getty Images
Female athletes are especially prone to ACL tears. Research has shown up to an 8-fold increase in the number of ACL tears in female athletes compared to their male counterparts. The reason for the increased risk has been debated for decades, but the focus of recent research has been on difference in neuromuscular control of the extremity. This means that men and women have differences in the position of their knee during critical sports movements such as landing, cutting and pivoting. Other theories have looked at differences in anatomy and hormone levels as possible factors in the different rate of ACL tears.


Prevent ACL Tears

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Specific activities may help prevent ACL injuries. Alexander Klemm / Getty Images

Preventing ACL tears has been the focus of recent research, especially the prevention of ACL tears in female athletes. Numerous theories have been proposed to explain why people may tear their ACL, and how they can be prevented. Current investigations have focused on neuromuscular training to prevent ACL tears.


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