ACL Tears: Symptoms and Treatment Recommendations

What Tearing This Knee Ligament Feels Like—and How to Heal

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 a popping sound and their knee giving out from under them. Many patients who sustain an ACL tear opt to have surgical treatment for this injury.

What Is the ACL?

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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 and it's located under the kneecap.

How a Tear Occurs

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An ACL tear is most often a sports-related injury. ACL tears can also occur during rough play, motor vehicle collisions, falls, and work-related injuries.

About 80 percent of sports-related ACL tears are "non-contact" injuries. This means that the injury happens without the contact of another athlete, such as a tackle in football.

Usually, ACL tears occur when pivoting or landing from a jump. The knee gives out from under the athlete when the ACL is torn.

Signs & Symptoms

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The diagnosis of an ACL tear is made by several methods.

First, a doctor notes the symptoms and asks the patient questions. 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 they may have felt as though their knee began to give out from under them. ACL tears generally cause knee swelling and pain. 

Upon examination, your doctor can look for signs of instability of the knee. Special tests place stress on the ACL and can detect a torn ligament.

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

Is Surgery Necessary?

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ACL tears do not necessarily require surgery. There are several important factors to consider before undergoing ACL surgery. First of all, do you regularly perform activities that normally require a functional ACL? Secondly, do you experience knee instability? If you don't play any sports that require an ACL, and if 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.

Reconstructive Surgery

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The usual surgery for an ACL tear is called an ACL reconstruction. A repair of the ligament is rarely a possibility, so the ligament is reconstructed using another tendon or ligament as a substitute for the torn ligament.
The are several ways to perform ACL surgery. The most significant choice that a surgeon makes is the type of graft that's 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 more than 90 percent of patients have no complications with ACL surgery.

Post-Surgical Rehab

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Post-surgical rehab is one of the most important (yet too often neglected) aspects of healing. 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 critical that each individual progress through rehab at his or her own pace—as the knee allows. Progressing too quickly or too slowly can be detrimental to the overall results from surgery, so it's important to ensure that your therapist and your physician are guiding your rehab.

Braces: Worth It?

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Many patients are given a knee brace after ACL reconstruction surgery. One common one is called a hinged Bledsoe brace. The brace is designed to limit range of motion, help stabilize your knee, and allow the ACL to heal the way that it should.

How necessary and helpful are these braces? Not all doctors agree on this. Braces have been the norm, but some recent research is starting to call their effectiveness into question. 

For example, one small 2013 study looked at people who wore a brace after ACL surgery versus people who didn't and found that there was no difference in ligament integrity four years after surgery. In fact, patients who didn't wear a post-surgical brace experienced less pain while playing sports or doing physical labor and had fewer injuries four years later. 

The bottom line: Talk to your doctor because every ACL tear and every surgery is different.

Sports & ACL Tears

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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, and basketball, among others.

Patients may be able to function in their normal daily activities without a normal ACL, but these high-demand sports may prove to be difficult. Therefore, athletes often choose 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.

Kids & Surgery

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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 lower than the risk of permanent knee damage if the ACL is not fixed.

ACL Tears in Women

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Female athletes are especially prone to ACL tears. Research has shown up to an eight-fold increase in the number of ACL tears in female athletes, compared with their male counterparts.

The reason for the increased risk has been debated for decades, but the focus of recent research has been on the 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 rates of ACL tears.


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Preventing ACL tears has been the focus of recent research, especially preventing them among 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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