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ACL Tears and Reconstruction

One of the most common, major injuries to the knee is a tear to the anterior cruciate ligament (ACL), one of four ligaments in the knee. These ligaments work together to stabilize the knee during activities.

The ACL can be injured by sudden stops or changes in direction or from landing incorrectly from a jump. Athletes who participate in twisting and pivoting sports like soccer, football, and basketball are more likely to injure their anterior cruciate ligaments.

Diagnosing an ACLTear
Nonsurgical Treatment for ACL Injuries
Surgical Reconstruction of the ACL
Surgical Choices for ACL Reconstruction: Autograft vs. Allograft
The Surgical Procedure
After Surgery

Diagnosing an ACLTear

An ACL tear usually occurs from a sudden event often accompanied by a "pop" sound. The knee will swell for a few hours, and it may be uncomfortable to walk. The knee can also feel unstable. A physician can confirm the tear with a physical examination and a magnetic resonance image (MRI) scan. When the ACL is completely torn, it cannot repair itself and thus the ligament function is lost. After a few months, the ligament tissue will break down and be absorbed by the body.

Nonsurgical Treatment for ACL Injuries

A small percentage of people will do well after an isolated ACL tear without surgical reconstruction. These individuals tend to be older and less active. They are not involved with activities or sports that involve pivoting or "cutting." Knee braces can help prevent instability episodes by "hobbling" the knee and assisting with sensory feedback. However, most active people will continue to have instability even with the most expensive custom knee brace.

Before deciding to pursue nonsurgical treatment in a knee that is ACL deficient, it is important to make sure that there is no other damage to the meniscal cartilage pads or other ligaments. An MRI scan can determine with excellent accuracy whether additional damage is present. If there is significant damage to the menisci, surgery is usually recommended. If knee surgery is scheduled for other problems, then most people decide to reconstruct the ACL at the same time.

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Surgical Reconstruction of the ACL

Most people with a torn ACL will experience instability, a feeling that the knee gives way or feels loose. This instability commonly results in a reduction in activities, especially sports. More importantly, the instability will usually lead to additional damage to the knee if left untreated.

Meniscal cartilage pad tears, articular surface cartilage injuries and additional ligament damage are common following untreated ACL tears. Some studies have shown that during the five years following an untreated ACL tear that 80 percent of individuals will have suffered additional damage because of instability. This damage often results in arthritis, a wearing out of the articular cartilage surfaces, which results in pain, stiffness and deformity. Most people with a torn ACL are unwilling to give up their activities and have a strong desire to prevent further damage to the knee. Therefore, most people elect to reconstruct the ACL.

The surgery to reconstruct the ACL involves taking a piece of tendonous tissue to replace the ACL. Tendons and ligaments share similar tissue composed primarily of collagen protein. The underlying concept behind the reconstructive surgery is that a tendon is surgically placed into the knee exactly into the position where the torn ACL was located. The tendon is fixed to the bone with biodegradable screws. Approximately 95 percent of the time, the body will then reestablish the blood supply to the tendon and over the weeks following the surgery this blood supply will bring new fibroblast cells that will repopulate the tendon bringing it back to life. As a result, the "new living ACL" is seemingly just as good as the original and should last a lifetime. Follow-up studies, which show maintenance of stability and active lifestyles for many years after ACL reconstruction, support this theory.

Surgical Choices for ACL Reconstruction: Autograft vs. Allograft

After deciding to undergo surgical reconstruction of the ACL, you and your surgeon must decide from where the reconstruction tissue will come. When the tissue comes from the same patient, it is called an autograft. When the tissue is taken from a different human donor, it is called an allograft. Tendons, such as the patellar tendon and hamstring tendon, can be used for autografts. The Achilles tendon, patellar tendon and hamstring tendon can be taken and used for allografts.

The Surgical Procedure

ACL reconstruction is performed using arthroscopy. Two to four skin incisions, or "portals," are placed in different areas in the front of the knee, dependent on tissue used. Through one of these portals the arthroscope - a small video camera the size of a pencil - is placed into the knee. With the magnification of the arthroscope, the physician can visualize any damage that has occurred. Through the other portals instruments are placed into the joint to remove, smooth or repair the tissues. All additional damage is corrected.

Water is infused through the arthroscope throughout the procedure and the tissues around the knee will absorb some of this water. The physician does not use a tourniquet device as there is no significant risk of bleeding. The ACL graft is placed into the knee through the small portals and placed into bone tunnels. The ACL graft will then be fixed with the latest biodegradable screws. These screws are MRI compatible and do not show up on X-rays. The small incisions are closed with absorbable sutures and skin tape, so that there are no stitches to remove. An ice machine is often recommended after surgery. Most people go home a few hours after surgery. You will need to use crutches and a brace, and your surgeon will most likely prescribe CPM (continuous passive motion) machine for home, which is used four to six hours a day to assist with motion.

After surgery, water mixed with small amounts of blood will often leak out of the portals and look like blood on the bandages. The drainage on the bandages is mostly water, which is normal.

Surgery is not without risks. Common risks include, but are not limited to, possible nerve injury, infection, bleeding, allergic reaction, and very rarely, death.

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After ACL Surgery

When it is time to leave the hospital or surgery center, you will need someone to drive you home, as well as to be with you during the first 12 to 24 hours after the procedure. It is important to do only what is necessary once you are home. You can use the restroom, get something to eat or answer the phone, but otherwise you should try to lie down with the leg elevated above the heart as much as possible. Take pain pills and anti-inflammatory medications immediately and regularly to help control pain. It is usually better to start taking the pain pills before the pain comes, so as not get "behind" the pain. Resume taking all medications, which you normally take.

You will likely be advised to start the CPM machine once you get settled at home. The range of motion is typically preset at zero to 40 degrees, and you will need to stay within this range. If you increase the motion too fast you may experience more pain the next day when the local anesthetic wears off. Also, if you chose to use an ice machine, continue for 24 to 48 hours.
Recovering from ACL Reconstruction

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This information provided by Dr. Warren King, M.D., director of the Sports Medicine Fellowship Program at Sutter Health’s Palo Alto Medical Foundation.