ACL Tear

What is an ACL Tear?

The Anterior Cruciate Ligament Reconstructive surgery is the medical term for ACL repair which occurs when the ligament ruptures or an ACL Tear. The ACL one of the most commonly injured ligaments of the knee. More often than not, the injury occurs from playing sports or a traumatic incident like a fall.

In the United States, every year on average there are over 200,000 ACL injuries. Of that, almost half are ruptures where the ligament fully separates from the bone. Which in almost every case, requires surgery and is a common injury for athletes, where approximately 70% of ACL injuries are related to no contact (pivoting, twisting, landing incorrectly from a jump, etc.) while only about 30% are related to direct contact (player to player contact).[1]

A basic understanding of the knee anatomy is needed to assist in understanding how an ACL injury occurs. Your knee is made up of bones, cartilage, muscles, tendons, and ligaments. There are three primary bones that make up your knee which includes the femur (thighbone), tibia (shin bone) and patella (knee cap).

Your knee has two main cartilages called meniscus. Located on the inside of the knee is the medial meniscus. Located on the outer side of the knee is the lateral meniscus. Both are meant to provide cushion and protection of the joint space.

There are a few main muscle groups around the knee, and they include the quadriceps (thigh muscle), hamstrings (muscles in the back of the upper leg), and your calf muscles. At the end of each muscle, there are tendons which help attach the muscle to the bone. Muscles around the knee allow for your knee to bend, extend, and slightly rotator or twist. They also control hip and ankle movements at the same time.

Ligaments are made up of tough tissue that attaches bone to bone and is meant to stabilize your joint. That means ligaments prevent unwanted, or extra, movement within or around the joint. Your knee has four main ligaments to help stabilize it.

The primary ligament, which is also the most vulnerable to injury, is the anterior (front) cruciate ligament (ACL). You have two ligaments that prevent extra sideways or gliding movements, and they are the medical (inside knee) collateral ligament (MCL) and the lateral (outside) collateral ligament (LCL).

The posterior (behind the knee) cruciate ligament (PCL) is the least likely of the ligaments to be injured. It is the strongest knee ligament, but it can be injured. Most commonly an injury to the PCL occurs because of trauma. The main job of the PCL is to prevent the tibia from moving backward too far.

All ligaments are subject to injury. When an injury does occur to a ligament, healing time can be slow as there is little blood supply to the tissue.

What causes an ACL tear?

Not only is an ACL injury common, but more than 50% of ACL injuries are in combination with other structural damage to the knee.[2] Usually, it is one of the other ligaments (MCL, LCL, or PCL) that tears and/or one of the menisci (medial or lateral).

So, why is the ACL so susceptible to injury? First off, the ACL has a big job to do. It stabilizes the femur and tibia bones. It also helps control knee movements such as twisting or rotation. ACL injuries typically occur when you are decelerating (slowing down forward movement) with a planted foot and your knee is twisting or pivoting. Jumping up and improperly landing is also a common cause for ACL tears.

ACL tears occur more often in women than in men. Also, the medical profession is reporting an increasing trend of more young (teenage) female athletes who suffer from an ACL tear than ever seen before.

More research needs to be done on exactly why women, especially young female athletes, are more prone to this injury. Some early research shows teenage females are more susceptible because of hormonal changes which impact laxity of the ligaments. In addition to laxity, there is some supporting evidence that young women have poorer alignment of the pelvis and femur which may cause undue stress of the ACL and other knee structures.

Not all ACL injuries are tears. Sometimes the ligament is overstretched, but still intact with the bone, which is a sprain. The concern with a sprained ligament is its susceptibility to future injury. With poor blood supply and due to the fibrous structure of the ligament, it may have a long-term impact by weakening it. Therefore, it may have difficulty stabilizing the joint as it did pre-injury.

An ACL injury may lead to osteoarthritis in the future. The reason is if the ligament can’t stabilize the joint as fully intended, that means there may be unwanted wear and tear of the joint which eventually breaks down the cartilage. Early and proper treatment of an ACL injury is critical to long-term health and function of the knee.

Symptoms of an ACL Tear

Symptoms will vary depending on the damage to the ACL. With a low-grade sprain, it may be painful, and some swelling may be present. You may feel tenderness in the front of the knee, but for the most part, you can walk and move your knee despite the pain.

If a partial or full tear occurs, you may experience sharp and intense pain at the front of the knee. Commonly people will report hearing a “pop” at the knee. With a tear, you may be unable to walk. In some cases, you can walk, but the knee may give out as which is due to the ligament’s inability to stabilize the joint. In addition to swelling and pain, you may find no matter how hard you try; you won’t have a full range of motion of the knee.

How is knee diagnosed?

If you believe your ACL is injured or torn, you are advised to seek immediate medical attention. It may be your athletic trainer, physical therapist, or physician that is first onsite to help. Until completing a full assessment, it is best to stabilizing the joint.

A physical exam of the knee by your physician or physical therapist can determine if your ACL is sprained or rupture. Often, despite the physical exam, imaging is also done in conjunction to ensure there are no other structures damaged. Typically, an MRI (magnetic resonance imaging) is ordered to assess all internal structures including bones, muscles, tendons, ligaments, and cartilage.

Treatment of an ACL Tear

You do not always need surgery with an ACL injury. If you suspect you have injured your ACL, seeking medical attention from either your physician or physical therapist is recommended. Remember, as a consumer of health care, you have a choice in your health care provider.

In most states, you can be seen by a PT first, without a physician’s order. To determine if your state has direct access, please visit the American Physical Therapy Association’s website Physical Therapy Direct Access By State.

With a low-grade sprain, within the first 24-48 hours applying the RICE rule is best. Rest the injured knee and avoid any activities that irritate it. Ice the knee down for 15-20mins several times a day to help manage any swelling or inflammation. Gentle compression and elevation will also help minimize any fluid from settling in the area.

You may need surgery with more serious damage to the knee. In some cases where surgery is not needed, starting physical therapy soon after this injury is recommended. Your physical therapist will work with you on decreasing inflammation, managing your pain, for a period may immobilize the joint and teach you how to walk on crutches to avoid weight bearing. In due time, when inappropriate the heal phase, your PT will begin gentle range of motion and strengthening exercises.

More often than not, you need surgery for an ACL tear. The surgery, known as reconstructive because the surgeon takes donor tissue and grafts it to the ACL. First, your surgeon will remove the damaged ACL tissue. He or she will then graft onto the good tissue your tendon tissue most often taken from your patellar or hamstring tendon. If there is any other damage within or around the knee, your surgeon will also surgically repair it.

Full recovery from ACL reconstruction surgery is a standard 8-12 month. Immediately after surgery, you can expect to be using crutches. Depending on the amount of damage and repair, your physician will determine how much, if any, weight bearing you will have on that leg.

You will start physical therapy soon after surgery. Your PT will help train you on the proper use of crutches as well as to safely transition from non-or partial weight bearing to full weight bearing. In addition to teaching how to be mobile safely, your PT will also work to manage your swelling and pain symptoms, which most often done with icing and gentle compression. Immediately after surgery, your surgeon will want to minimize movement of the knee so that the tissue can start to heal, which may require bracing.

During therapy, your PT will be gentle and make safe movements with your knee, which is done to avoid stiffness and weakness. Most often your physician and PT will not want you moving your leg by yourself, but instead under a medical professional’s supervision.

Approximately 4-6 weeks post-operative, gentle strengthening will begin. During this phase, more weight bearing will be allowed. The main focus will be to start rebuilding your quadriceps and hamstring muscles strength. You will more than likely still have a limitation in your knee range of motion.

With more time passing allowing you to heal, for the next two to six months your PT will advance your strengthening exercises and will introduce balance exercises, which is a critical part of recovery to retrain your muscles, tendons, and ligaments to stabilize the knee. Each person’s injury and healing process vary, so guidance from your PT and physician indicate when you can return to functional activities and sports.

Next Steps

If you have experienced an ACL injury, make sure you get immediate care from a local physician. Once properly diagnosed, your physician will establish an appropriate plan. PT is highly recommended with an ACL injurty, both pre-operatively as well as post-operatively.

You have a choice in your deciding which PT you would like to receive therapy from. To get started with a highly qualified PT today, visit Find A Clinic. This link will help you find a local PT that has top national rankings for treating the knee.

[1] http://www.moveforwardpt.com/SymptomsConditionsDetail.aspx?cid=d8e73ca8-71f4-48a7-92f8-675bca38232c

[2] http://orthoinfo.aaos.org/topic.cfm?topic=a00297

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