Anterior Cruciate Ligament (ACL) Surgery

Medically Reviewed By William C. Lloyd III, MD, FACS

What is anterior cruciate ligament (ACL) surgery?

ACL surgery is the surgical reconstruction or replacement of the anterior cruciate ligament (ACL) in the knee. The thighbone (femur), shinbone (tibia), and patella (kneecap) meet to form your knee joint. Ligaments connect these bones to each other. Your ACL is one type of knee ligament. It is a band of tough, fibrous connective tissue that stabilizes your knee.

Injuries requiring reconstruction or replacement of the ACL are common, especially among athletes. ACL reconstruction surgery can help restore pain-free range of motion, stability, and function to a knee joint after ACL injury.

ACL surgery is a common but major surgery with risks and potential complications. You may have less invasive treatment options. Consider getting a second opinion about all of your treatment choices before having ACL surgery.

Types of ACL surgery

Injured or torn ACLs do not heal well by sewing the ligament back together. Instead, ACL reconstruction surgery uses a connective tissue graft to rebuild or replace your injured ACL. Both ligaments and tendons are connective tissues. Your body heals around the graft over several months. 

The types of ACL surgery procedures include:

  • Allograft reconstruction. An allograft is a piece of cadaver connective tissue, usually a tendon. Allografts come from a tissue bank. Allograft reconstructions require only one incision and cause less pain than an autograft fusion. However, there is a small risk of serious infection, including HIV and hepatitis.

  • Autograft reconstruction. An autograft is a piece of your own connective tissue. Doctors usually take an autograft from a piece of the patellar (kneecap) tendon. This is the gold standard for ACL autograft reconstruction. Your patellar tendon will heal itself and re-grow the missing portion over time. Other autograft sites are your hamstring and quadriceps tendons. These sites do not heal as reliably as your patellar tendon. An autograft requires an additional large incision, lengthens surgery time, and causes more post-operative pain than allograft reconstruction.

  • Synthetic or artificial graft reconstruction. Artificial ligament graft materials have been studied in trials but have not performed as well as human tissue grafts. Synthetic grafts are still experimental at this time.

  • Xenograft reconstruction. A xenograft is a piece of connective tissue taken from non-human animal sources. Medical scientists are currently conducting human trials of xenograft reconstructions.

Other procedures that may be performed

Your doctor may recommend one or more procedures in addition to ACL surgery:

  • Meniscectomy is the surgical repair or trimming of a torn meniscus. Your knee has two menisci. They are made of cartilage and function as shock absorbers for your knee joint.

  • Other ligament reconstructions. Your knee contains four ligaments including your ACL. Other knee ligaments may also need reconstruction depending on your injury.

  • Patellar realignment is the surgical repositioning of the kneecap.

  • Synovectomy is the surgical removal of part of an inflamed synovial membrane. Synovial membranes are tissues that line joints, including your knee.

Why is anterior cruciate ligament (ACL) surgery performed? 

ACL surgery is a major surgery that reconstructs or replaces a torn anterior cruciate ligament (ACL) in your knee. Your doctor may only consider ACL surgery for you if it suits your needs and lifestyle. 

Your doctor may recommend surgery to treat complete ACL tears for: 

  • Active adults who want to return to heavy labor or sports that require pivoting, turning, twisting, or hard sideways movements of the knee

  • Combined injuries when other knee injuries are present with an ACL tear

  • Older children or teens whose growth plates have closed. ACL surgery carries a risk of damaging the growth plate in younger children. This can lead to growth problems. Your child’s surgeon may recommend delaying or modifying ACL surgery to lower the risk of growth plate damage.

  • Symptoms of functional instability including knee pain or a knee that gives way during daily activities. This increases the risk of more knee damage.

Nonsurgical treatment may be a reasonable option when these conditions are not met. Nonsurgical treatment may be a good option for elderly people with a low activity level. Ask your doctor about all of your treatment options and consider getting a second opinion before having ACL surgery.

Who performs anterior cruciate ligament (ACL) surgery?

An orthopedic surgeon will perform your ACL surgery. An orthopedic surgeon specializes in the medical and surgical treatment of diseases of the bones and connective tissues.

How is anterior cruciate ligament (ACL) surgery performed?

Patients often need physical therapy for at least three weeks before ACL surgery. You may need to wear a knee brace during this period. The purpose of pre-operative physical therapy is to gain full range of motion in your knee before surgery. Patients who have ACL surgery while their knee is still stiff, swollen, or limited in motion tend to have trouble regaining motion after surgery.

Surgical approaches to ACL surgery

ACL surgery is performed in a hospital or outpatient surgery setting. It is a minimally invasive or arthroscopic surgery. Your surgeon will insert special instruments and an arthroscope through small incisions in your knee. An arthroscope is a thin, lighted instrument with a small camera. The camera transmits pictures of the inside of your body to a video screen viewed by your surgeon during the surgery.

Minimally invasive surgery generally involves a faster recovery and less pain than open surgery. This is because it uses smaller incisions and causes less damage to tissues and organs.  The arthroscope allows your surgeon to thread surgical tools around structures instead of cutting through or displacing them as in open surgery. 

Using an autograft for ACL reconstruction involves making a large incision over the autograft tendon. Because of this, autografts lengthen surgery time and tend to cause more post-operative pain.

Your surgeon will also advise you on which procedure is best for you and how long you need to stay in the hospital based on your diagnosis, age, medical history, general health, and possibly your personal preference. Learn about the different ACL surgery procedures and ask why your surgeon will use a particular procedure for you.

Types of anesthesia that may be used

Your surgeon will perform ACL surgery using either general anesthesia or regional anesthesia, depending on the specific procedure. 

  • General anesthesia is a combination of intravenous (IV) medications and gases that put you in a deep sleep. You are unaware of the surgery and do not feel any pain. You may also have a peripheral nerve block infusion in addition to general anesthesia. A peripheral nerve block infusion is an injection or continuous drip of liquid anesthetic. The anesthetic flows through a tiny tube inserted near your surgical site. It controls pain during and after surgery.

  • Regional anesthesia is also known as a nerve block.  It involves injecting an anesthetic around certain nerves to numb a large area of the body. You will likely have sedation with regional anesthesia to keep you relaxed and comfortable.

What to expect the day of your ACL surgery

The day of your surgery, you can expect to:

  • Talk with a preoperative nurse. The nurse will perform an exam and ensure that all needed tests are in order. The nurse can also answer questions and will make sure you understand and sign the surgical consent form.

  • Remove all clothing and jewelry and dress in a hospital gown. It is a good idea to leave all jewelry and valuables at home or with a family member. Your care team will give you blankets for modesty and warmth.

  • Talk with the anesthesiologist or nurse anesthetist about your medical history and anesthesia 

  • A surgical team member will start an IV.

  • The anesthesiologist or nurse anesthetist will start your anesthesia. 

  • A tube will be placed in your windpipe to protect and control breathing during general anesthesia. You will not feel or remember this or the surgery as they happen.

  • The surgical team will monitor your vital signs and other critical body functions. This occurs throughout the surgery and your recovery until you are alert, breathing effectively, and your vital signs are stable.

What are the risks and potential complications of anterior cruciate ligament (ACL) surgery?  

As with all surgeries, ACL surgery involves risks and potential complications. Complications may become serious and life threatening in some cases. Complications can occur during surgery or recovery.  

General risks of surgery 

The general risks of surgery include: 

  • Anesthesia reaction, such as an allergic reaction and problems with breathing

  • Bleeding, which can lead to shock

  • Blood clot, in particular a deep vein thrombosis (DVT). A DVT in one of your legs can block blood flow or travel to your lungs causing a pulmonary embolism.

  • Infection 

Potential complications of ACL surgery

Complications of ACL surgery include: 

  • Failure of the graft to heal
  • Growth plate injury in children
  • HIV or hepatitis infection (with allograft reconstructions)
  • Knee instability or pain
  • Kneecap pain, especially with patellar tendon autografts
  • Nerve, muscle, or blood vessel damage
  • Patellar tendon weakness and rupture after harvesting for an autograft
  • Stiffness and loss of range of motion
  • Weakness or numbness in your leg or foot

Reducing your risk of complications

You can reduce the risk of certain complications by following your treatment plan and:

  • Following activity, dietary and lifestyle restrictions and recommendations before surgery and during recovery

  • Informing your doctor or anesthesiologist if you are nursing or if there is any possibility of pregnancy

  • Notifying your doctor immediately of any concerns, such as bleeding, fever, increase in pain, or wound redness, swelling or drainage

  • Taking your medications exactly as directed 

  • Telling all members of your care team if you have any allergies

How do I prepare for my anterior cruciate ligament (ACL) surgery? 

The steps you take before surgery can improve your comfort and outcome. You can prepare for ACL surgery by:

  • Answering all questions about your medical history and medications. This includes prescriptions, over-the-counter drugs, herbal treatments, and vitamins. It is a good idea to carry a current list of your medical conditions, medications, and allergies at all times.

  • Getting preoperative testing as directed. Testing will vary depending on your age, health, and specific procedure. Pre-operative testing may include a chest X-ray and other imaging tests, ECG (electrocardiography), blood tests, and other tests as needed.

  • Losing excess weight before the surgery through a healthy diet and exercise plan

  • Not eating or drinking before surgery as directed. Your surgery may be cancelled if you eat or drink too close to the start of the procedure because you can choke on stomach contents during general anesthesia or sedation.

  • Stopping smoking as soon as possible. Even quitting for a just a few days can be beneficial and help the healing process.

  • Taking or stopping medications exactly as directed. This may include not taking aspirin, ibuprofen (Advil, Motrin), and blood thinners.

Questions to ask your doctor

Facing surgery can be stressful. It is common for patients to forget some of their questions during a doctor’s office visit. You may also think of other questions after your appointment. Contact your doctor with concerns and questions before surgery and between appointments.

It is also a good idea to bring a list of questions to your pre-operative appointments. Questions can include:

  • Why do I need ACL surgery? Are there any other options for treating my condition?

  • What type of ACL surgery procedure will I need?

  • How long will the procedure take? When can I go home?

  • What restrictions will I have after the surgery? When can return to work, sports, and other activities?

  • What assistance will I need at home?

  • How should I take my medications? 

  • How will you treat my pain?

  • How much physical therapy will I need after surgery?

  • Will I need a brace after surgery? If so, when and how long should I wear it?

  • When should follow-up with you?

  • How should I contact you? Ask for numbers to call during and after regular hours.

What can I expect after my anterior cruciate ligament (ACL) surgery?

Knowing what to expect can help make your road to recovery after ACL surgery as smooth as possible. 

How long will it take to recover?

You will stay briefly in the recovery room after surgery until you are alert, breathing effectively, and your vital signs are stable. You will probably go home the same day of surgery. 

You may have a sore throat if a tube was placed in your windpipe during surgery. This is usually temporary, but tell your care team if you are uncomfortable. 

Recovery after surgery is a gradual process. You will wear a knee brace and use crutches for several weeks after your surgery. Your doctor will also refer you to an exercise rehabilitation program or physical therapy to help you recover. This includes exercises to restore range of motion and build knee strength. 

Graft healing can take many weeks. Recovery time varies depending on the specific procedure, type of anesthesia, your general health, age, and other factors.  Full recovery takes at least four to six months, but may take as long as a year. It generally takes at least six months before you can return to sports.

Will I feel pain?

Pain control is important for healing and a smooth recovery. There will be discomfort after your surgery. Your doctor will treat your pain so you are comfortable and can get the rest you need. Call your doctor if your pain gets worse or changes in any way because it may be a sign of a complication.

When should I call my doctor?

It is important to keep your follow-up appointments after ACL surgery. Contact your doctor for questions and concerns between appointments. Call your doctor right away or seek immediate medical care if you have:

  • Bleeding

  • Breathing problems, such as shortness of breath, difficulty breathing, labored breathing, or wheezing

  • Calf pain, or swelling of the calf, ankle or foot

  • Change in alertness, such as passing out, unresponsiveness, or confusion

  • Fever. A low-grade fever (lower than 101 degrees Fahrenheit) is common for a couple of days after surgery and not necessarily a sign of a surgical infection. Follow your doctor's specific instructions about when to call for a fever.

  • Inability to urinate, pass gas, or have a bowel movement

  • Numbness or tingling in the affected extremity 

  • Pain that is not controlled by your pain medication or pain that gets worse or changes

  • Unexpected drainage, pus, redness or swelling of your incision or knee joint

How might ACL surgery affect my everyday life?

ACL surgery may cure your condition or significantly reduce your symptoms so you can lead an active, normal life. Successful ACL surgery restores knee strength and stability. Some people feel more comfortable returning to work or sports after recovery with the security of a knee brace for extra support.

Was this helpful?
  1. ACL Graft Choices. Ortho Associates Centers for Orthopaedics.
  2. ACL Injury: Does It Require Surgery? American Academy of Orthopaedic Surgeons.
  3. Anterior Cruciate Ligament Injuries. American Academy of Orthopaedic Surgeons.
  4. Knee Problems. National Institute of Arthritis and Musculoskeletal and Skin Diseases.
  5. Pile, JC. Evaluating postoperative fever: A focused approach. Cleveland Clinic Journal of Medicine. 2006;73 (Suppl 1):S62.
Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Nov 13
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