Sports Medicine - Knee


Anterior Cruciate Ligament Reconstruction

 

Anterior Cruciate Ligament Injuries of the Knee

What is the ACL?

The Anterior Cruciate Ligament (ACL) is a ligament that connects the tibia to the femur. It serves to prevent the tibia (leg) from moving forward relative to the femur (thigh). The ACL is in the center of the knee - it crosses the PCL - hence the name - "cruciate". It is the primary stabilizer of the knee for lateral mobility and athletic activities.

How does someone injure the ACL?

It is frequently injured in contact sports (such as football) and pivoting sports (such as soccer and skiing) - although there are many scenarios for injury to this ligament. Usually the patient complains of a sudden injury to the knee and may feel a “pop” at the time of the accident. Often, there is a significant amount of swelling within the knee.

What happens after the ACL injury?

It depends on the severity of the injury and whether there are any other associated injuries, such as a medial collateral ligament tear or a meniscal tear. Often the swelling resolves after 7 to 10 days. Some patients will be able to function without any problems after they get over the initial injury, especially if they had only a partial tear. The majority, however, will notice "instability" - the feeling that their lower leg is shifting forward on their thigh bone. For some, this will be a minor nuisance; for others, it will be a significant disability.

How can an ACL tear be treated?

The first step is to reestablish knee motion. Because of the swelling (caused by blood in the knee), the knee will be difficult to extend (make straight) for several days to weeks. It is important to get the motion back as quickly as possible (after resting for a few days) to prevent a permanent loss of motion ("contracture"). Once this is accomplished, the decision needs to be made whether surgery is necessary. If surgery is not necessary, then strengthening excercises, particularly of the hamstrings are prescribed. This is followed by proprioceptive exercises designed to help you regain control of your knee's position while walking. Often, a brace will be prescribed to provide stability.

Who needs surgery?

This is a very complicated question and generally can only be answered by discussion with your orthopedic surgeon. There are a few guidelines, however. Typically, the decision to reconstruct the ACL is based on the following:

1. Patient's age and activity level.
2. Associated injuries, such as a meniscal tear, medial collateral ligament injury, or significant cartilage injury.
3. Response to rehabilitation.
4. Amount of instability and magnitude of the patient's symptoms.

Generally speaking, a young high school football player who injures his ACL and wants to continue to compete at the same level or higher (eg. college play) will require a reconstruction. Another player may decide that he doesn't want to play football ever again and is happy decreasing his functional activities, such as surfing the internet and swimming, this person may not require an ACL reconstruction. A 35 year old skiier who has injured her ACL and medial meniscus, and wants to continue to ski recreationally, should probably have her ligament reconstructed. As you can see, the permutations are endless - the decision needs to be made on a patient-by-patient basis with a surgeon who knows you and your lifestyle demands.

What is an ACL reconstruction?

The ACL is replaced by another piece of tissue to function in a similar fashion as the original ACL. The goal of this surgery is to have this tissue eventually grow back into place, in the same position as the old ACL, so that it can function in a similar fashion.

Why can't you just repair the ACL?

Usually, when the ACL tears completely, its two ends are completely separated within the joint. In addition, the blood supply to the ligament is permanently disrupted. Without an artery to feed it, the ligament cannot heal. Finally, when the knee moves, it tends to pull the two ligament ends apart. If you were to put the patient in a cast to try to prevent this from happening, the knee ends up very stiff. In the past, many surgeons had tried to repair the ACL, but the results after this type of surgery were not very good.

Why can't I have my reconstruction right away?

If you and your physician have already made the decision to reconstruct the ligament, it is important to wait a few weeks after the injury to regain the motion in your knee. Failure to do so could mean that you might have a stiff knee after surgery.

What kind of ACL reconstructions are there?

There are many variations on the same theme, but basically the different types of reconstructions depend on the type of tissue ("graft") used to replace the ACL.

The most common is the bone-patellar tendon-bone ("BTB") graft. The patellar tendon is the tendon that connects your kneecap (patella) to your leg (tibia). The central 1/3rd of this ligament of the injured knee, as well as rectangles of bone on both ends are used in this graft. The bone grafts are typically fixed on both ends (femur, tibia) with screws. The advantage of this graft is that it is very strong because the bone rectangles help it to heal into place quickly. Most NFL physicians use this graft for this reason. However, there may be symptoms at the donor site that can cause discomfort or difficulty kneeling.

The Hamstring tendons are another form of ACL replacement graft. One or two of the hamstring tendons in the back of the knee (medial - on the inside of the knee) are used in this graft. Don't worry - you have more than enough hamstrings without these two. The advantage of this graft is that it does not require taking any bony blocks out of your patella or tibia, hence there is a lower occurence of pain under the kneecap (although not a zero occurrence). It is also thicker in cross-section than the patellar tendon graft - therefore the actual graft substance is stronger. However, its weak spot is in its attachment to the bone - it is usually attached by a button (right outside of the bone - and/or screws on the femur, and by screws in the tibia. Return to full sports with these grafts is around 6 months.

Finally, there are allografts. These tissues (various ligaments/tendons) are taken from a cadaver donor. They are rigorously tested for viruses including HIV and Hepatitis (using social history of the donor, antibody testing, and testing for actual viral DNA) - the risk of transmission is less than one in a million with these current testing techniques. The advantage of these grafts is that initial recovery is a lot faster because we do not have to use any of your native tissue and you have less pain after the reconstruction. However, the graft may take longer to completely integrate in your body because it is foreign tissue. Eventually your body replaces it with your own tissue. With an allograft, you can return to work much sooner because we have not had to harvest any of your own tissue (eg. patellar tendon or hamstring) and it is therefore much less painful. However, we may delay your return to aggressive sports longer than the other two grafts to allow the tissue to integrate - 6-8 months, or so. Longterm results with these grafts have been very good.

How does one decide which graft to use?

The most important factor in this decision is the experience of your surgeon with a particular graft type. Some surgeons prefer one type of graft over another, or have a significant experience with only one graft type. At Parkview Musculoskeletal Institute, Drs. Price and Dr. Burra have extensive experience with all common ACL graft types and will tailor the decision based on your special needs, including:

1. Whether or not you had pain under your kneecap before your injury.
2. Your activity level, age, and size.
3. Your need to return to work or sports as soon as possible.
4. The results of he latest clinical trial.
5. Your preference.

What can I expect at surgery?

The surgery is usually performed on an outpatient basis at the hospital and patients may stay overnight for pain management. The procedure usually takes about 2 - 3 hours. You will experience a moderate amount of pain for a few days, and some pain for a couple weeks (every person is different). Cryotherapy (cold therapy) can help to reduct your pain significantly. If you work in a job that you can do mostly sitting-down, you should be able to return to work within a week or so. Patients often use protective braces and will be on crutches fro approximately 4 weeks.

What are the risks of ACL surgery?

Risks include: swelling, loss of motion, residual pain under the kneecap, recurrent instability, and infection. Swelling and loss of motion can occur in around 5% of patients - in most cases these can be treated without further surgery. Sometimes, if the loss of motion is significant, we may have to go back in and remove some of the scar tissue in the knee. Pain under the patella (kneecap), also known as "anterior knee pain" or "chondromalacia patella" is a common problem with any type of ACL reconstruction. It happens most commonly in bone-patellar tendon-bone grafts (15-35%), least in allografts (around 10%), and somewhere in-between for hamstrings (10-15%). Recurrent instability can occur for various reasons; sometimes a new injury tears the reconstructed ACL and sometimes there is a problem with your healing of the ACL tissue and it never heals as tightly as necessary. Physicians a tParkview Musculoskeletal Institute utilize the latest techniques to decrease the probability of this happening - currently less than 3-5% of our patients ever have this problem. Deep infection is fortunately very rare (<1%), but serious - it will require a second surgery to clean out the infected tissue and treatment with antibiotics.

What does the post-operative rehabilitation entail?

First you will need to regain motion, then regain strength. Gradually we get you back into activities such as walking, jogging, swimming, and biking. Finally, you will start doing specific exercises depending on the sport in which you usually participate. This whole process takes about 6 months and depends on your effort, the type of graft you had, and the activities to which you want to return. All of this is performed in conjunction with a physical therapist who follows a specific plan prescribed by us.

What are the controversies in the post-operative period?

Sports surgeons love to argue about certain things, and ACL reconstructions are at the top of the list. Current controversies include:

1. Bracing. Some surgeons believe in bracing, others do not. Personally, we customize the decision regarding a brace to each patient. All patients receive a brace after surgery; some will wear custom “sports braces” when the return to high-demand activities. Not all insurances will pay for a sports brace - you need to check with yours. If your insurance does not cover it, they can be somewhat expensive.
2. Weight-bearing. Some surgeons let you put as much weight as possible on your leg after surgery, others prefer to limit you and ask you to use crutches for a period of time. This also depends on whether you had a meniscal or other additional ligament repair.
3. "Accelerated rehabilitation". This rehabilitation protocol attempts to get you back to sports earlier than 6 months post-op. Some surgeons have reported excellent results with this protocol, others have reported some problems with this technique. As this is still under debate, you should not try to pick your surgeon based on which rehabilitation protocol they use or whether they promise to get you back to sports at 6 months versus 4 months, for example.

Physicians usually differ in their opinions on these topics. Most importantly, you want your doctor to be familiar with all these issues and have good reasons why they pick one over the other.