Anterior Cruciate Ligament ACL Reconstruction

The anterior cruciate ligament, or ACL, is one of the most important ligaments in your knee. Deep in the middle of the knee joint,  it connects the thigh bone (femur) and leg bone (tibia) together and provides critical stability to the joint.

When the ACL tears with an injury, it does not heal.  Because of its location, it does not have the same capacity to heal as other ligaments, like the medial collateral ligament, to repair itself.  As a graduate student I spent time on research projects that proved the MCL can heal but the ACL does not.  A torn ACL will give you a feeling of instability, as if the knee might come apart, with certain movements, like stepping off a curb, or trying to run.

As a result, anterior cruciate ligament ACL reconstruction is  performed to restore knee stability.  With advances in arthroscopic surgery it is performed with minimal incisions, low complication rates, and faster return to activities.  It has become one of the most common sports medicine procedures and is highly successful for most patients.

Causes of an ACL Tear

ACL tears usually occur during sports activities that involve twisting, pivoting or hyperextending your knee.  This can happen with a sudden change in running direction, for example a cutting move while playing soccer, landing a jump poorly, being struck on the outside of the knee by another player, or while slowing down quickly during a fast run.  The majority of ACL tears occur without being hit by another person or player.  Other factors may come in to play increasing your risk of an ACL tear.  Female athletes, for example, have a 5-6 time higher risk of tearing the ACL playing soccer than their male counterparts.

Symptoms of an ACL Tear

ACL Reconstruction

When the ACL tears, most feel or hear a loud ‘pop’ in the knee and typically fall.  This can be painful, but pain is not always present.  Usually within a few hours, the knee becomes quite swollen because of bleeding in the joint.  Nearly all players that have this occur during sports are not able to go back to play, although some may try and have the feeling of being unstable on the knee.

Often, with the injury, other structures in the knee are also injured, like the meniscus, possibly other ligaments such as the medial collateral ligament, and at times cartilage damage can occur.

Diagnosis of an ACL Tear

An ACL tear is diagnosed by a detailed history of how the injury happened, as well as a careful physical examination of the knee.  In medicine, the rule is that 99% of the diagnosis is found in the history and examination.  During the examination, the joint is observed and moved using specific exam tests.  The ‘Lachman’ test can be highly specific for an ACL tear.  This can be compared with the normal knee in most cases to see if there is a difference between the two sides.  The pivot shift test is another useful test to assess abnormal motion of the knee that happens with an ACL tear.

Additional testing will usually include xrays and MRI scans.  Both are important and provide information from a different perspective.  An MRI alone is not enough.  The X-ray provides detailed information about bony structures in the knee.  These can help rule out a fracture.  

ACL Reconstruction Procedure

ACL reconstructionThe anterior cruciate ligament is reconstructed during an outpatient procedure that takes between an 60 to 90 minutes.  The goal of ACL reconstruction surgery is to tighten your knee and to restore its stability. Patients receive a general anesthetic for this procedure.  A dose of antibiotics is given through the IV that is safe for you to help prevent infection.  Often a nerve block is also given to help keep you comfortable after surgery.  Different tissue grafts can be used for an ACL – we can discuss how to choose what is best elsewhere than this page
ACL Graft Choices
Ask Dr. Hacker: Should I have ACL reconstruction surgery
ACL reconstructions: Why do they fail ?
If needed, a tendon or ligament graft is first harvested from your knee and then prepared for use.  The surgery is done using advanced arthroscopic techniques and is minimally invasive.  Three very small incisions are made around the knee.  A small camera attached to a long narrow tube allows me to see inside the joint and first assess everything that was injured to determine how to repair the joint.  Each structure in the knee is assessed and a plan is made for repair if needed.  This is all done through these three small incisions.  Once everything else in the knee is repaired, two small tunnels are created in the bone of the femur and tibia.  The tissue graft used for the ACL is then drawn up into the knee through these tunnels and secured in place.  Placement of these tunnels is critical to success of the procedure.  Time is taken to ensure proper placement.  All the incisions are then closed and dressings are placed to help minimize infection.

Rehabilitation after anterior cruciate ligament reconstruction

Physical therapy is essential after surgery. This usually begins within 1 to 2 days. The goal for the first six weeks after surgery is to reduce swelling, restore your comfort, and slowly get your flexibility back. There are home exercises to perform every day. Most patients attend physical therapy sessions twice a week. After six weeks, we typically begin light strengthening. Crutches and bracing is often used up until this point. As strength slowly increases, your activity level will also be allowed to slowly increase. By three months out, the strength program is in full swing. I would typically not let patients run until at least 4 to 5 months out. Return to sport is guided by a few things. It is not just a time factor. Not only does full-motion need to be restored, but you need to have your normal strength back, as well as your normal endurance and normal agility. Each of these takes time. In some cases I’ve seen this happen at six months. For some patients, this takes a full year. You’ve invested in your knee and you wanted to go well. It is worth spending the time making sure your rehab is complete before returning to activities he love.

Medications after anterior cruciate ligament reconstruction

MedicationsTypically, there are three medications after surgery. First, I have my patients take aspirin daily for the first 10 to 14 days to help prevent blood clots. This is a risk with any surgical procedure, and can result in serious complications such as pulmonary embolus. We do everything we can to prevent this. Next, most patients take some form of an anti-inflammatory. This can be ibuprofen 800 mg three times a day. This will help with swelling, pain, and inflammation. Finally, the last medication is a narcotic. This is only if necessary and for as short a time as possible. We will talk about all this at your preoperative visit to be sure it is clear.

Complications of anterior cruciate ligament reconstruction

Our goal, of course, is to minimize complication risk.  Risks may include numbness, infection, blood clots, nerve damage, graft failure, knee stiffness and pain among others.  Making a decision for surgery is serious and we take it seriously along side you.  Ask questions and be sure it is right for you before choosing to go forward !