Understanding ACL Injury

Ligaments are tough, non stretchable fibers that hold your bones together. A tear to the anterior cruciate ligament (ACL) of your knee joint is among the most common sport-related injuries. The ACL connects the thighbone (the femur) to the shinbone (the tibia) and acts to prevent your thigh bone from moving too far forward over the knee joint. This ligament also helps stabilize the shinbone from rotating out of the knee joint.

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.

After ACL reconstruction, performing rehabilitative exercises may gradually return full flexibility and stability to your knee. Building strength in your thigh and calf muscles to support the reconstructed knee is a primary goal of rehabilitation. You may also need to use a knee brace for a short time, and it is important not to return to full activity too soon to prevent re injury.

What is the ACL and how can it be injured?

Ligaments are tough, non-stretchable fibers that hold your bones together. The ACL, or anterior cruciate ligament, is one of four primary ligaments that connect the femur (thigh bone) to the tibia (shin bone) at the knee. The ACL’s position — running diagonally through the center of the knee — enables the ligament to provide stability to the knee, limiting side-to-side rotation and preventing the tibia from moving ahead of the femur. Along with ligaments, the knee also contains a cushion of articular cartilage that caps the ends of each leg bone, as well as additional shock-absorbing cartilage, called the meniscus, between them.

Injury to the ACL is one of the most common knee ligament injuries. Even though most ACL injuries occur during a sports activity, ACL injuries aren’t just caused by being tackled while playing football. Injury results when the ACL is stretched beyond its limit. You may have injured your ACL by pivoting quickly, landing poorly from a jump or by hyperextending your knee.

What are the symptoms of an ACL injury?

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 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 fiber-optic 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.