Anterior Cruciate Ligament (ACL) Surgery


Sarah Lewis, PharmD

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:

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  • 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: 


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  • 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 s