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ACL Reconstruction

The anterior cruciate ligament, or ACL, plays a vital role in the movement of athletes. An injury to this ligament can result in pain and immobility, and your doctor may recommend reconstruction surgery as a treatment option. 

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Without proper care, a tear in your ACL (anterior cruciate ligament) can be a debilitating injury, especially for athletes and people who live an active lifestyle. When the tear is severe, you may need ACL reconstruction surgery to restore function and stability to the knee.

What is ACL reconstruction surgery?

ACL reconstruction is used to treat complete tears of the anterior cruciate ligament, one of several pieces of connective tissue that stabilize your knee. If you tear the ACL completely, it can't repair itself. When that happens, a surgeon can take connective tissue from elsewhere in your body and graft it to your knee to perform the function of your torn ACL. In some cases, you may choose to receive a graft from a tissue donor rather than from your own body.

ACL repair vs reconstruction

Not every torn ACL requires reconstruction. An ACL repair sews the existing ACL tissue back together, whereas an ACL reconstructive surgery uses a tissue graft to replace the torn ACL.

When a repair is possible, some doctors believe it leads to a faster recovery. However, older techniques for ACL repair have high failure rates, and modern repair techniques don’t yet have much data on long-term outcomes. For now, ACL reconstruction is still the standard of care in most cases.

Who is a candidate for ACL reconstruction surgery?

ACL reconstruction can be an appropriate treatment for active patients who have a completely torn ACL, especially younger patients who play sports that place high demands on the knee. Older patients whose lives don't include sports that require rapid pivoting, like basketball, soccer, and tennis, may be able to get by without surgery, even living relatively comfortably with a completely torn ACL.

ACL reconstruction surgery is especially important for young athletes who perform sports involving rapid direction changes, such as cutting and pivoting movements. Without an intact ACL, these athletes are at higher risk of other knee injuries, including a torn meniscus.

However, people with partial tears, especially young patients, don't always need surgery. A partial tear to an ACL may heal on its own.

A Mass General Brigham sports medicine specialist can assess the degree of your ACL tear using physical tests, such as the Lachmann test and the pivot shift test, which evaluate your knee's stability. Based on the results of the tests and other factors like age, medical history, and lifestyle, your care team will determine whether to treat your ACL injury surgically.

Other considerations about eligibility

Patients who are candidates for ACL reconstructive surgery need to wait about a month after the injury before having the procedure. This gives time for the swelling to go down and the knee to regain mobility. Undergoing surgery too early can cause scarring in the knee that may limit range of motion after the operation.

On the other hand, you shouldn't wait too long to see a doctor, who will help you determine a surgical or nonsurgical treatment plan. Waiting too long can cause other (potentially permanent) injuries due to instability in the knee and may increase your risk of needing a second surgery, called a revision, to repair the graft.

How does ACL reconstruction surgery work?

Modern ACL reconstruction surgery is a minimally invasive procedure using arthroscopic techniques. Your surgeon will make a few small incisions around your knee area and a larger one where they harvest the tissue graft. The surgeon will insert small instruments and a camera into these openings to perform the surgery with minimal trauma to your body.

During the surgery, the surgeon will cut away the remains of your damaged ACL. Then, they'll collect a piece of connective tissue from elsewhere in your body, most commonly the hamstring, patellar (kneecap) tendon, or the quadriceps tendon. They'll drill two small tunnels where the ACL should attach, insert the ends of the graft tissue into the holes, and secure the tendon to the bone using screws, buttons, or other hardware. The ACL reconstruction fixture hardware is typically permanent without a need for future removal.

ACL reconstruction surgery cost

For many people, cost is a serious concern when getting medical care, especially surgery. The average cost of ACL reconstructive surgery in the U.S. is around $10,000, though prices vary considerably. Fortunately, many insurance plans—including Medicare and Medicaid—cover ACL surgery when it's medically necessary.

Preparing for ACL reconstruction surgery

The knee is a delicate joint, and ACL reconstruction is a major surgery that places a lot of demands on your body in recovery. You'll need to follow some guidelines in the period before you have ACL reconstructive surgery to achieve the best results.

As you get ready for surgery, you should:

  • Practice using crutches: ACL surgery is typically an outpatient procedure, which means you'll go home the same day you have the operation. However, you won't be able to walk normally for a while after the operation, so you should get used to crutches ahead of time.
  • Ask your doctor about medicines: Talk with your healthcare provider about any medications you take. You may need to temporarily stop medications that can affect the surgery and recovery period, such as blood thinners. 
  • Find out what anesthesia you'll receive: ACL surgery is usually performed under general anesthesia, but some facilities use other methods. The type of anesthesia and the timing of your operation will affect when you need to stop eating before your surgery.
  • Bring comfortable clothes: Your knee will be stiff and swollen after the procedure, so it's helpful to bring comfortable, loose-fitting clothes.
  • Get your knee in shape: ACL surgery can have severe complications if your knee is still inflamed when you have the operation. Treating it with ice, anti-inflammatory drugs, and physical therapy exercises can help you reduce inflammation before the operation.

Pre-ACL reconstruction exercises

Along with rest, ice, and anti-inflammatories, performing "pre-hab" physical therapy exercises can help you achieve the best possible outcomes from your surgery. You'll be prescribed a physical therapy regimen to prepare your knee for the operation, which can lead to better results. The program will focus on restoring function to the muscles that support the knee, regaining range of motion, and reducing swelling in the knee.

What happens during ACL reconstruction surgery?

On the day of your operation, you'll come to the hospital with a friend or family member who can take you home afterward. Bring a comfortable change of clothes, crutches, a leg brace, and proof of insurance. You'll need to come to the hospital on an empty stomach—your care team will give you specific directions on when to stop eating and drinking.

You'll receive anesthesia, and the surgeon will perform the operation. Afterward, you'll wake up and be kept for observation for a short time.

How long does ACL reconstruction take?

ACL reconstruction surgery typically takes about two and a half hours. 

What to expect after ACL reconstruction surgery

Most people are sent home the same day as their procedure. If you have problems with anesthesia, you may stay overnight for observation. When it's time to go, you'll be able to walk with crutches and a leg brace, but you'll need someone to accompany you.

You may experience pain in the first few days after your surgery, though your doctor will also prescribe pain medication. Some people experience discomfort due to the screws that hold the reconstructed ACL in place.

Scarring after your ACL reconstructive surgery should be minimal, with just thin scars developing at the incision sites. In rare cases, you may experience a thicker scar. Too much internal scarring can cause functional problems, but effective pre-hab can reduce the amount of scarring inside the knee and support good knee function after the operation.

Recovery from ACL reconstruction

Returning to your activities, especially sports, can take up to a year after ACL reconstructive surgery, depending on your age, health, medical history, lifestyle, and other factors.

You should spend the first week after your surgery resting. You'll ice your knee, take any medications the doctor prescribes, and you may begin doing some physical therapy exercises to regain range of motion and reduce swelling. Eating enough and focusing on a balanced diet will help your body begin the recovery process.

While the first week of recovery is mostly about rest, you'll gradually take on more activity:

  • Your body recovers from the operation during the first few weeks. You’ll focus on anti-inflammatory therapies like ice and continue with gentle physical therapy exercises.
  • During weeks 4-6, your body will reshape the new ligament to ensure it does its job. This is the most critical phase of recovery.
  • After the first two months or so, you'll start walking without an assistance device. You may also return to some light activities.
  • Six months after the operation, you should be able to return to more intense athletic activities, such as jumping and running.
  • At a year from the surgery, you should be back at your pre-injury training level, even for sports that involve fast cutting and pivoting, though you should always be careful to avoid re-injuring your knee.

You'll wear a leg or knee brace after your ACL reconstruction surgery and perform daily physical therapy. A physical therapist will guide you on home exercises on the days you don't see the therapist.

  • Beginning: At first, you may see the physical therapist two or three times a week. In this period, you’ll regain control of your leg muscles and focus on reducing swelling and regaining basic strength and mobility. You'll gradually transition out of using your crutches over about four to six weeks.

  • Middle: The second phase of physical therapy focuses on regaining your full pre-operative strength and mobility. You may ride a stationary bike, run on a treadmill, or do other activities that strengthen the leg. During this period, you'll transition from a post-surgery leg brace into an athletic brace. This period lasts about two months.

  • End: Once you've regained your strength and range of motion, you'll gradually start returning to full activity under the supervision of your doctor and physical therapist. You may still wear a brace for a while as you return to sports that challenge the knee. The final phase lasts from four to eight months, depending on the patient and their lifestyle.

It can be frustrating to stay still for so long and perform simple exercises each day, especially for athletes. But it's important to follow your physical therapy program.

Don't take on new physical activities before your surgeon and physical therapist say you're ready. It takes time for your body to incorporate your new ACL. Returning to full activity too early can damage the new ACL.

The length of a full recovery depends on the type of graft your surgeon used and your health, medical history, and previous activity level. Most people can resume normal daily activities after several months, but a full recovery can take a year or more, especially for athletes, who require more from their knees than non-athletes.

Athletes' physical therapy program will help them gradually return to their previous training and fitness level. However, a full return to sports training can take anywhere from 6-12 months—or longer in some cases depending on your sport. A return to sports involving fast cutting and pivoting takes about a year following ACL reconstruction surgery.

Recovery times are longer for athletes who play high-risk sports like soccer, basketball, or football than for those who participate in lower-risk sports like rowing or cycling. Your surgeon and physical therapist will let you know when you can safely resume your activities in full.

Izzy’s Story: Returning from a Torn ACL

A torn ACL derailed Izzy Graziano’s final season of high school soccer. Learn how Elizabeth Matzkin, MD, and the Mass General Brigham Sports Medicine team paved the way for her return to competing.

Read Izzy's story
An athlete sits up halfway on a medical examination table during physical therapy as a doctor, who is seated, checks her left knee

FAQs about ACL reconstruction

Even though ACL reconstruction is usually performed as a minimally invasive arthroscopic procedure, it's considered a major surgery because of how complex and demanding it is on your body.

It depends on the pace of your healing and recovery process.

Most people can walk with crutches and a leg brace within a few days of the operation. As you perform physical therapy, your knee will gradually become stronger and more stable. You'll phase out the crutches, usually over six to eight weeks, as your knee recovers and your new ACL integrates into your body.

Patients may return to daily activities and work without restrictions after about six months. Returning to higher-level training, sports, and competition may take up to a year or more.

There's no way to provide a definitive answer—every patient is unique. However, assuming the surgery doesn't have complications and the patient is committed to their physical therapy program, most people can make a full return to their previous activities. Surgery restores full function in over 80% of cases. Even with full function, your knee may be more prone to pain and swelling after the surgery.

Unfortunately, knee osteoarthritis is common in people who have received ACL reconstruction surgery after an ACL tear. This may be because of slight changes to biomechanics after the surgery, though the cause isn't completely understood.

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