The ACL, or anterior cruciate ligament, is a connective tissue in the knee. This important ligament helps with your stability and mobility. ACL tears are common in athletes who play sports that require lots of cutting and pivoting, such as soccer, basketball, rugby, and skiing. However, an ACL tear can occur at any time to anyone. Here’s what you should know about an ACL surgery and what to expect if you need ACL surgery.

What causes an ACL injury?

The most common way ACLs are torn is when the hip doesn’t rotate enough to perform a cutting or pivoting movement, coupled with a sudden reduction in speed. This puts the knee joint in the position of providing the extra twist to perform the movement while it’s stabilizing the leg.

This trauma can be a partial tear or a total tear and is often coupled with other injuries like a torn meniscus. Partial tears may present without any symptoms, whereas a total tear can prevent you from walking without aid.

Common symptoms of a partial and total ACL tear are:

  • Swelling
  • Pain
  • Popping sound during injury
  • Reduced range of motion
  • Instability in the knee
  • Catching or locking
  • Reduced capacity or inability to bear weight

ACL surgery is performed when the ACL is torn. Because the body can’t heal or re-grow a torn ACL, surgery is the only option to repair the tissue.

When do you need ACL surgery?

The goal of ACL surgery is to repair or replace your ACL. ACL surgery is typically an arthroscopic outpatient surgery lasting about an hour. If you have a partial tear, your doctor will remove the damaged tissue and may graft on new tissue depending on the size of your tear. For a total tear, your doctor will remove the damaged tissue and replace it with new tissue.

If you are receiving a tissue graft or a total ACL reconstruction, you’ll have the option to use your own tissue (autograft) or donor tissue from a cadaver (allograft).

Using your own tissue requires an additional surgery to harvest the tissue, typically from the hamstring or patellar tendon. If your doctor can’t get enough tissue from the primary site they select they’ll need to harvest additional tissue, leaving you with multiple surgical sites. Autografts slow your recovery time, and you may not be a good candidate for them. In this case, you’ll need to use donor tissue.

All donor tissue is thoroughly sterilized in high tech labs that are highly regulated and thoroughly inspected. If you opt to use cadaver tissue, your surgery will be shorter since your doctor will already have the tissue on hand prior to surgery. There also won’t be an increase in recovery time or additional surgical sites.

What Should I Know About ACL Surgery? |

Is ACL surgery always necessary?

ACL surgery may not be necessary if you have a partial tear, but should be considered if your intention is to continue playing sports. Individuals who do not lead a highly active lifestyle or have no symptoms may opt not to undergo surgery.

Always consult with your doctor to determine the best treatment plan for your lifestyle. Your doctor performs several tests to determine if your ACL is torn and needs surgery. These may include:

  • X-ray
  • Lachman’s test
  • MRI
  • Surgical exploration (if necessary)


An X-ray may be necessary to determine if there has been any bone damage.

It’s possible for an ACL tear to cause damage to the surrounding bones when it explosively tears. This is usually the first test your doctor will run.

Lachman’s test

This is a physical test your doctor will perform.

While lying down and bending your knee, your doctor will place their hands behind your calf near the back of the knee and pull your tibia forward. If your tibia slides forward your ACL is likely compromised.


An MRI (magnetic resonance imaging) test is necessary to see the connective tissues in the knee and diagnose an ACL tear. This gives your doctor a great look at the soft tissue of the knee. Check out this UCSF article for information on preparing for an MRI.

Surgical exploration (if necessary)

If your doctor can’t get the necessary information to diagnose your ACL tear by performing the above tests, they may suggest exploratory arthroscopic surgery. During this surgery, your doctor inserts a camera into the knee joint. This allows them to see any potential damage up close.

If your tear is minor and you have no or few symptoms, your doctor may recommend physical therapy to strengthen the muscles around the knee joint to better support the knee and ACL. Hip stretches can also help by providing increased mobility to the hip and reducing the stress on the knee.

For many patients, though, the best option is surgery.

What should I do before ACL surgery?

Before your surgery, it will be necessary to discontinue the use of certain medications and drugs. This is typically required two weeks prior to surgery but can be longer depending on the prescription. Your doctor may also prescribe physical therapy prior to surgery to improve mobility in the knee and increase your chances of a successful surgery.

In addition, you’ll be required to have a capable, responsible adult available to take you to and from the surgical facility. You may also require assistance for the few days immediately following surgery.

As your surgery date approaches you may receive some prescriptions from your doctor – make sure to fill them before your surgery. You’ll also be restricted from eating or drinking up to 24 hours prior to your surgery. Carefully follow all pre-op instructions provided by your doctor.

What should I expect during surgery?

The day of your surgery you’ll be checked in and outfitted with a full-leg compression sleeve on the leg that isn’t being operated on. These can be uncomfortable, but you’ll often have to wear them for up to 48 hours after surgery.

Your anesthesiologist may administer a femoral nerve block, especially if you’re having a total reconstruction. This quick procedure can be uncomfortable but it helps pain overall. It requires injecting the medication into your femoral nerve, near your groin in the affected limb.

During surgery, your doctor will make three incisions in the knee to insert the camera and tools and flush the joint with fluid. They’ll then cut away the damaged tissue, or the whole ACL if you’re having a total reconstruction. Your doctor will repair any additional damage found during surgery.

For a partial tear that requires grafting, your doctor will graft the tissue onto your ACL before closing your site and dressing the wounds.

When undergoing a total reconstruction, your doctor will first make attachment sites for the new tissue by drilling one hole into your tibia and one hole into your femur. Your doctor will attach the tissue by inserting the ends into the drill sites and securing it with screws. They may also use different screws in each site to ensure a tight fit. Your doctor will then close and dress the wounds.

The following video gives a 3D overview of what occurs during surgery.

Post-op care

After your surgery is complete you’ll spend some time recovering in the facility as you wake from anesthesia. A post-op nurse monitors you and manages your pain.

If you’ve had an ACL reconstruction you may be in a significant amount of pain, so be sure to tell your nurse.

The adult responsible for you will receive instructions from your doctor that includes:

  • Post-op care instructions
  • A packet with images from the surgery
  • Prescriptions for your medication

These prescriptions should be filled as soon as possible.

What are the risks of ACL surgery?

While ACL surgery is a fairly commonplace procedure, it still is surgery with its own risks. Common risks of an ACL surgery can include:

  • Infection
  • External scarring
  • Internal scar tissue
  • Blood clots
  • Side effects from anesthesia
  • Post-operative pulmonary edema
  • Pneumonia
  • Tissue rejection
  • Future surgeries
  • Chronic pain
  • Lifestyle changes
  • Depression
  • Muscle loss


To reduce the risk of infection, keep the surgical site clean and follow all care instructions from your doctor.

External scarring

Because ACL surgery requires cutting into your knee, external scarring is unavoidable. Scars are typically small for arthroscopic surgery, but much larger for open knee surgery.

Internal scar tissue

There’s no way to predict exactly how the inside of your knee will heal once your doctor closes you up. It’s possible to develop lumps of internal scar tissue that can:

  • Inhibit mobility
  • Cause additional knee pain
  • May require future surgeries to remove

Additional surgeries are not uncommon after an ACL reconstruction, even if you’re working with the best doctor.

Blood clots

Blood clots are more common in low limb surgeries. To reduce your risks, your doctor will restrict the use of certain medications that thin your blood and require that you wear compression leggings following surgery.

Blood clots are a serious complication and can be deadly. Always follow all your doctor’s care instructions to reduce your risk.

Side effects from anesthesia

Some individuals experience side effects form anesthesia, like nausea or total body aches. If you’ve had side effects from anesthesia in the past, discuss these with your doctor prior to surgery.

Post-operative pulmonary edema

Post-operative pulmonary edema is a condition where fluid builds up in your lungs following surgery, making it difficult to breath. It is most common in patients with pre-existing heart conditions.

Tissue rejection

If you’re receiving a graft or a total ACL reconstruction and have opted to use cadaver tissue instead of your own, there’s a small chance that your body could reject the tissue. This could lead to infection and additional surgeries.


Some individuals develop pneumonia following ACL surgery due to a combination of reduced physical activity and reduced lung capacity from anesthesia.

To prevent pneumonia, it’s important you perform all breathing exercises prescribed by your doctor. If you believe you have developed pneumonia, visit your doctor immediately.

Future surgeries

It’s possible you may need additional surgeries to remove scar tissue that has built up following the initial surgery. In addition, individuals who have had ACL surgeries are more likely to tear the ligament again, possibly requiring another surgery.

Chronic pain

Some individuals develop chronic pain following ACL surgery, including pain when performing certain actions like walking or squatting, and general pain when not moving. Discuss all chronic pain with your doctor and physical therapist to develop the best treatment approach.

Lifestyle changes

Depending on your circumstances, you may have to make some lifestyle changes following ACL surgery, including limiting or reducing certain physical activities. While these limitations are often temporary, if you opt to not have ACL surgery they will likely be permanent to prevent further injury.


Limitations on typical normal activities like sports or even walking without aid can cause distance from social groups or enjoyment that can lead to depression.

Muscle loss

Restrictions on weight bearing on your injured leg prior to and after surgery can lead to muscle loss from inactivity. Muscle loss can further restrict your lifestyle after surgery and takes a lot of effort to rebuild.

How long does it take to recover from ACL surgery?

Recovery periods vary from patient to patient. If there are no other conditions restricting your mobility, you will attend physical therapy as soon as the day after surgery. Physical therapy can last up to a year, but most patients complete physical therapy within four to six months. Most are able to discontinue the use of crutches or other walking aids within six to eight weeks after ACL surgery.

It’s important to work with your doctor and physical therapist to develop a recovery plan that works best for your needs. If you are returning to sports or other strenuous activities, your recovery period may be longer and more intense.

If you are experiencing chronic knee pain, believe you may have a torn ACL, or are experiencing continued pain that extends outside the normal recovery period provided by your physician, a pain specialist may be able to help. You can find a pain doctor in your area by clicking the button below or looking for one in your area by using the tips here:

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