ACL injury: Should I have knee surgery?

Get the facts
Compare your options
What matters most to you?
Where are you leaning now?
What else do you need to make your decision?

1. Get the Facts

Your options

Have ACL surgery followed by a physical rehabilitation (rehab) program.
Try rest, exercise, and physical rehab.

This Decision Point is not meant for children or teens. Their bones have not stopped growing, so there are other things to think about. This Decision Point is also not for people who have had ACL surgery or are having revision surgery.

Key points to remember

Surgery may be done for most healthy adults of any age who want to keep up activities that require a strong, stable knee.
Surgery with physical rehabilitation is your best chance to have a stable knee and an active lifestyle without more pain, injury, or loss of strength and movement in your knee. But this also depends on how badly your ACL was damaged. You might think about surgery if:
- Your ACL is completely torn or partially torn and unstable.
- You are very active in sports or have a job that requires knee strength and stability (such as construction work).
- You have long-lasting (chronic) ACL deficiency that affects your quality of life.
- You have hurt other parts of your knee, such as the cartilage, meniscus, other knee ligaments, or tendons, or you have broken bones within the knee joint.
- You are willing to complete a long rehab program.
If you're willing to do several months of rehab first, you might want to try it before having surgery.
If you wait too long to fix a torn ACL and you start to get chronic ACL deficiency, the surgeon may not be able to fix all of your joint damage. You may still have pain and swelling. It's important to have surgery before your unstable knee causes other joint problems.
If you are thinking about surgery for anterior cruciate ligament (ACL) injuries, you may want to talk to more than one orthopedic surgeon about your knee injury. You may get different ideas from other doctors about how surgery could be done. Choose the surgeon with whom you feel the most comfortable and who has a good reputation in your community.

FAQs

What are the anterior cruciate ligament (ACL) and an ACL injury?

The anterior cruciate ligament (ACL) is one of four knee ligaments that connect the upper leg bone (femur) with the large lower leg bone (tibia). The ACL keeps your knee stable by:

Keeping your lower leg bone from sliding forward or turning when the leg is straight.
Preventing your knee from being stretched or straightened beyond its normal limits.
Supporting the knee ligaments that keep your knee from bending sideways.

See a picture of the knee and the ACL .

An ACL injury is a tear in one of the knee ligaments. It can be:

A small or medium tear of the ligament (partial tear).
A complete tear of the ligament (rupture).
A separation of the ligament from the upper or lower leg bone (avulsion).
A separation of the ligament and part of the bone from the rest of the bone (avulsion fracture).

When any of these things happen, the lower leg bone may slide forward on the upper bone. This may feel like your knee is giving out. An ACL tear may also hurt other bones or joints inside the knee.

What are the risks of an ACL injury?

The risks of an ACL injury depend on:

How bad the injury was.
Whether other parts of your knee also were injured.
Whether you stop or limit activities that require a stable knee.
Whether you complete a rehab program.

If nothing is done, the ACL injury may turn into chronic ACL deficiency. Your knee may become more and more unstable and may give out more often. The abnormal sliding within the knee also can hurt cartilage. It can trap and damage the menisci in the knee and can also lead to early osteoarthritis.

If you can live with a loose knee and avoid doing things that make your knee unstable, you may not get osteoarthritis.
If you keep doing things that make your knee give way and become painful and swollen, you risk future joint problems and disability.

If you wait too long to fix a torn ACL and you start to get chronic ACL deficiency, the surgeon may not be able to fix all of your joint damage. You may still have pain and swelling even after surgery. It's important to have surgery before your unstable knee leads to other joint problems.

How successful is ACL surgery?

About 60 out of 100 people who have ACL surgery return to the full level of activity they had before their injury, and 40 do not.¹ Of those 40 people who don't return to their full level of activity, most have reduced pain and good knee function.² A few people—less than 10 out of 100 who have ACL surgery—will still have knee pain and instability.³

What are the risks of surgery and rehabilitation?

ACL surgery has few risks. Risks and problems that can occur during rehab and recovery include:

Loss of motion in the knee joint.
Grating (or grinding) of the kneecap.
Pain and swelling during daily activities or sports.

2. Compare Options

	Have ACL surgery	Try rest, exercise, and rehabilitation
What is usually involved?	You will have spinal or general anesthesia. Depending on the type of ACL surgery you have, you may go home the same day or spend a few days in the hospital. You will do physical rehabilitation for several months to a year. Your rehab will continue until your knee is stable and strong. You should be able to return to normal activities or sports in 4 to 6 months.⁴	You rest and reduce activity. Your doctor may suggest that you use crutches or a splint. You use ice for swelling. You wrap your knee with an elastic bandage and keep it propped up on a pillow when you sit or lie down. You take anti-inflammatory medicines for pain. You do physical rehabilitation until your knee is stable.
What are the benefits?	Surgery with rehabilitation offers the best chance for making your knee stable again. About 60 out of 100 people who have ACL surgery return to the full level of activity they had before their injury, and 40 do not.¹ Of those 40 people, most have good knee function and reduced pain.²	Rest and rehab may be enough to heal your injury or at least make it stable enough so that you can do some activities. If you decide to have surgery later, you will be in better condition for it because of your rehab program. You avoid the risks of surgery.
What are the risks and side effects?	A few people—less than 10 out of 100 who have ACL surgery—will still have knee pain and instability.³ All surgery has risks, including bleeding, infection, and nerve damage. Your age and your health also affect your risk. Other risks of surgery or problems that occur after surgery include: Loss of motion to the knee joint. Grating (grinding) of the kneecap. Pain and swelling during daily activities or sports.	You won't be able to keep doing activities that caused your injury. You may not regain full use of your knee. If you wait too long to fix a torn ACL and you start to get chronic ACL deficiency, the surgeon may not be able to fix all of your joint damage.

Personal stories

Are you interested in what others decided to do? Many people have faced this decision. These personal stories may help you decide.

If you need more information, see the topic Anterior Cruciate Ligament (ACL) Injuries.

Personal stories about having surgery for an ACL injury

These stories are based on information gathered from health professionals and consumers. They may be helpful as you make important health decisions.

"My knee is only a little unstable after my ACL injury. My doctor said the decision to have surgery is really up to me. I am going to do some intensive rehab for a few weeks and see how my knee progresses. If I can avoid surgery, I'd like to do that. "

— Don, age 42

" I'm not a competitive athlete, but I am very active and I enjoy running, hiking, and bicycling. My doctor said that my ACL tear wasn't too bad, but I am definitely going to have surgery. I think surgery is my best chance of being able to continue to do all the things I did before I hurt my knee. "

— Susan, age 38

" I'm not a very active person, and so it isn't too important to me that my knee be stable. It only has a small amount of instability right now, so I am not going to have surgery. I feel like the risks of the surgery are more than the risks of not having it, at least for someone like me. "

— Carmen, age 53

" I need a stable knee to do my job well, and I'd also like to avoid getting osteoarthritis early if I can. I'm going to have the reconstruction surgery, even though I know the rehab is long. It's the best chance I have of getting a strong, stable knee. "

— Peter, age 45

3. Your Feelings

Your personal feelings are just as important as the medical facts. Think about what matters most to you in this decision, and show how you feel about the following statements.

Reasons to choose ACL surgery

Reasons to choose rest, exercise, and physical rehabilitation

I need a healthy knee for work.

My work does not depend on my having a healthy knee.

More important

Equally important

More important

I'm active and involved in sports, so I need a healthy knee.

I'm not that active or involved in sports.

More important

Equally important

More important

I accept the risks of surgery.

I don't want to have surgery for any reason.

More important

Equally important

More important

I can commit to a long rehabilitation program after surgery.

I don't know if I can commit to a long rehab program after surgery.

More important

Equally important

More important

My other important reasons:

More important

Equally important

More important

4. Your Decision

Now that you've thought about the facts and your feelings, you may have a general idea of where you stand on this decision. Show which way you are leaning right now.

ACL surgery

Rest, exercise, and physical rehab

Leaning toward

Undecided

Leaning toward

5. Quiz Yourself

Check the facts.

1. Do rest, exercise, and rehabilitation offer you the best chance for a stable knee?

Yes
No
I'm not sure

You are right. Surgery with physical rehabilitation offers the best chance to have a stable knee and an active lifestyle.

2. If you're not sure about surgery, is it okay to try physical rehab first?

Yes
No
I'm not sure

You are right. If you're willing to do several months of rehab first, you might want to try it before surgery.

3. Can you cause other problems by waiting too long to have surgery?

Yes
No
I'm not sure

You are right. If you wait too long to fix a torn ACL and you start to get chronic ACL deficiency, the surgeon may not be able to fix all of your joint damage.

Decide what's next.

1. Do you understand the options available to you?

2. Are you clear about which benefits and side effects matter to you?

3. Do you have enough support and advice from others to make a choice?

Certainty.

1. How sure do you feel right now about your decision?

Not sure at all

Somewhat sure

Very sure

2. Check what you need to do before you make this decision.

Nothing. I'm ready to take action.
I want to discuss the options with others.
I want to learn more about my options.

3. Use the following space to list questions, concerns, and next steps.

References

Citations

Biau DJ, et al. (2007). ACL reconstruction: A meta-analysis of functional scores. Clinical Orthopaedics and Related Research, 458: 180–187.
Fu FH, et al. (2000). Current trends in anterior cruciate ligament reconstruction. American Journal of Sports Medicine, 28(1): 123–130.
Noyes FJ, Barber-Westin SD (2001). Revision anterior cruciate ligament reconstruction: Report of 11-year experience and results in 114 consecutive patients. AAOS Instructional Course Lectures, 50: 451–461.
McMahon PJ, Kaplan LD (2006). Anterior cruciate ligament injuries section of Sports medicine. In HB Skinner, ed., Current Diagnosis and Treatment in Orthopedics, 4th ed., pp. 180–183. New York: McGraw-Hill.