Anterior Cruciate Ligament (ACL) Injuries Causes, Symptoms, Diagnosis, Treatment, Prevention

Anterior Cruciate Ligament (ACL) Injuries Causes, Symptoms, Diagnosis, Treatment, Prevention

What is an Anterior Cruciate Ligament (ACL) Injury?

Ligaments are tough, nonstretchable fibers that hold your bones together. The ACL connects the thighbone (the femur) to the shinbone (the tibia) and helps stabilize the knee joint. A tear to the Anterior Cruciate Ligament (ACL) is among the most common sport-related injuries. This typically happens by sudden twisting movements, slowing down from running, or landing from a jump. You may hear a popping sound at the time of injury. Your knee may give way and begin to swell and hurt.

The ACL can tear when it’s stretched beyond its normal range. This typically happens by sudden twisting movements, slowing down from running, or landing from a jump. You may hear a popping sound at the time of injury. Your knee may give way and begin to swell and hurt.

Because the ACL is not capable of healing itself (ligaments, unlike muscles, do not have their own blood supply), it can only be reconstructed (that is, replaced) surgically — it cannot simply be repaired. Less active people may choose to treat a torn ligament nonsurgically with a rehabilitation program focusing on muscle strengthening and lifestyle changes. Surgical reconstruction, however, may help many people recover full function after an ACL tear. Your doctor can discuss these different options with you and help choose what is right for you.

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What Causes an Anterior Cruciate Ligament (ACL) Injury?

Ligaments are strong bands of tissue that connect one bone to another. The ACL, one of two ligaments that cross in the middle of the knee, connects your thighbone (femur) to your shinbone (tibia) and helps stabilize your knee joint.

Most ACL injuries happen during sports and fitness activities. The ligament may tear when you slow down suddenly to change direction or pivot with your foot firmly planted, twisting or hyperextending your knee.

Landing awkwardly from a jump can also injure your ACL, as can falls during downhill skiing. A football tackle or motor vehicle accident also can cause an ACL injury. However, most ACL injuries occur without such contact.

What Sports have a High Incidence of Anterior Cruciate Ligament (ACL) Injuries?

Many sports require a functioning ACL to perform common manoeuvers such as cutting, pivoting, and sudden turns.

These high demand sports include football, rugby, netball, touch, basketball, tennis, volleyball, hockey, dance, gymnastics and many more. 

You may be able to function in your 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 injuries have be known to curtail many promising sporting careers.

What are the symptoms of an Anterior Cruciate Ligament (ACL) Injuries?

You may have heard a popping sound when your injury first occurred. After that, severe pain and severe swelling of the entire knee probably sent you right to your doctor or emergency room. Other symptoms include an inability to move your knee normally, or walk without pain or a feeling of instability. In order to diagnose you properly, your doctor will consider your symptoms, ask you about your activity leading up to the injury, and examine your knee carefully. Because half of all ACL injuries are also accompanied by injuries to the other soft tissue in the knee, your doctor will want to look at the big picture. In addition to examining your knee in specific positions and manipulating its movement, your doctor will likely want you to have X-rays (to check for fractures) or an MRI (magnetic resonance imaging).

How is an Anterior Cruciate Ligament (ACL) Injury Diagnosed?

On clinical knee examination, your physiotherapist or sports doctor will look for signs of ACL ligament instability. These special ACL tests place stress on the anterior cruciate ligament, and can detect an ACL tear or rupture.

An MRI may also be used to determine if you have an ACL tear. It will also look for signs of any associated injuries in the knee, such as bone bruising or meniscus damage, that regularly occur in combination with an ACL tear.

X-rays are of little clinical value in diagnosing an ACL tear.

How is an Anterior Cruciate Ligament (ACL) Injury treated?

Your doctor may recommend different treatment options depending on your particular symptoms and the severity of your injury. Together you will also consider how your injury is affecting your lifestyle and your participation in your favorite activities.

Brace yourself.

While you and your doctor determine the extent of your injury and the appropriate course of action, you may be given a knee brace for support and stability. The brace will also help minimize the risk of aggravating the injury. During this time, your doctor may prescribe or recommend the use of anti-inflammatory medications (like aspirin or ibuprofen) and cool packs applied to the knee to reduce inflammation and pain.

Get the right moves

A conservative course of action may serve you well if your doctor determines that you have only a partial ACL tear, your knee is stable during routine activities, and you completely refrain from participation in any high-risk sports and activities. In this case, your doctor may recommend several specific strengthening exercises to perform on your own throughout the day. In addition, your doctor may require you commit to a full course of physical therapy. During physical therapy sessions, a trained therapist will work closely with you to help reduce your pain, increase your motion, and improve your thigh and calf strength. As you progress, you will also be taught how to more safely engage in your favorite sport or activity, if appropriate.

Understand your surgical options

Unlike muscles, ligaments don’t have their own blood supply and cannot heal themselves. If you are still experiencing pain after all other conservative measures have been taken, your doctor may suggest surgery to repair the tear, help relieve your pain and help restore your mobility. Surgical procedures to repair a torn ACL are aimed at restoring the stability and full function of your knee. Most ACL repairs involve surgical reconstruction, during which the ACL is replaced by another tendon from your own body (autograft).

Today’s techniques, matched with newer instruments, may allow your doctor to reconstruct your ACL during arthroscopic surgery (using a fiberoptic scope through a small incision). To secure your repair, your doctor will use pins or screws, such as Stryker’s Biosteon Bio-Composite Interference Screws and Cross-Pin System. Be sure to talk with your doctor about the best treatment option for you.

Commit to feeling better

After surgery, you will likely be able to go home the same day. You may have to wear a splint or brace for a period of time while you heal. Most people use crutches for the first few weeks. Full recovery from ACL repair may take up to a year. Rehabilitative physical therapy will require six to nine months. Complete rehabilitation often depends on your commitment to following your doctor’s recovery recommendations. It is critical that you don’t return to full activity too soon. Your doctor will help you determine how soon after surgery you can safely begin participating in routine, and then more demanding, activities.

Anterior Cruciate Ligament (ACL) Injuries in Children

ACL reconstruction surgery is the standard treatment for young, active people who sustain an ACL tear. But what happens when you’re young and your bones are still growing?

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

Your knee surgeon is the best person to discuss whether ACL reconstruction is advisable or not. 

Anterior Cruciate Ligament (ACL) Surgery

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

You may have heard of a Lars Procedure, which is a new ACL reconstruction procedure. In some, but certainly not all, ACL ruptures a stub of the old ligament can be used as a part of the repair procedure, which can hasten your recovery time. Your surgeon will know whether a Lars procedure is an option for you or not. There are higher re-rupture risks involved.

Risks of ACL surgery include:

  • infection, 
  • persistent instability and pain, 
  • knee 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.

Prevention for Anterior Cruciate Ligament (ACL) Injuries

Improve your conditioning. Training programs that have been shown to be effective in helping to reduce the risk of ACL injuries typically include strengthening and stability exercises, aerobic conditioning, plyometric exercises, "jump training," and risk-awareness training. Exercises that improve balance also can help when done in conjunction with other training exercises.

Strengthen your hamstrings. Women athletes in particular should make sure to strengthen their hamstring muscles as well as their quadriceps.

Use proper techniques. If your sport involves jumping, learn how to land safely. Studies have shown that if your knee collapses inward when you land from a jump, you are more likely to sustain an ACL injury. Technique training along with strengthening of some of the hip muscles can help to reduce this risk.

Check your gear. In downhill skiing, make sure your ski bindings are adjusted correctly by a trained professional so that your skis will release appropriately when you fall.

Wearing a knee brace has not been found to be helpful in preventing ACL injuries.