Surgery Overview

Surgery for
anterior cruciate ligament (ACL) injuries involves
reconstructing or repairing the ACL.

  • ACL reconstruction surgery uses a
    graft to replace the ligament. The most common grafts
    are autografts using part of your own body, such as the tendon of the kneecap
    (patellar tendon)
    or one of the hamstring tendons.
    Sometimes the quadriceps tendon from above the kneecap is used. Another choice is allograft tissue, which is taken from a deceased donor.
  • Repair surgery
    typically is used only in the case of an avulsion fracture (a separation of the
    ligament and a piece of the bone from the rest of the bone). In this case, the
    bone fragment connected to the ACL is reattached to the bone.

ACL surgery is usually done by making small incisions in the knee
and inserting instruments for surgery through these incisions (arthroscopic surgery). In some cases, it is done by cutting a large incision
in the knee (open surgery).

ACL surgeries are done by
orthopedic surgeons.

In reconstruction
of a partial or complete tear of the ACL, the best time for surgery is not
known. Surgery immediately after the injury has been associated with increased
fibrous tissue leading to loss of motion (arthrofibrosis) after
surgery.footnote 1 Some experts believe that surgery should be
delayed until the swelling goes down, you have regained range of motion in your
knee, and you can strongly contract (flex) the muscles in the front of
your thigh (quadriceps).footnote 1 Many experts recommend
starting exercises to increase range of motion and regain strength shortly
after the injury.

In adults, age is not a factor in surgery,
although your overall health may be. Surgery may not be the best treatment for
people with medical conditions that make surgery a greater risk. These people
may choose nonsurgical treatments and may try to change their activity levels to
protect their knees from further injury.

Arthroscopic surgery

Many orthopedic surgeons use
arthroscopic surgery rather than open surgery for ACL injuries because:

  • It is easy to see and work on the knee
  • It uses smaller incisions than open
  • It can be done at the same time as diagnostic arthroscopy
    (using arthroscopy to find out about the injury or damage to the knee).
  • It may have fewer risks than open surgery.

Arthroscopic surgery is done under
regional (such as spinal) anesthesia or
general anesthesia.

What happens

During arthroscopic
ACL reconstruction, the surgeon makes several small incisions-usually two or
three-around the knee. Sterile saline (salt) solution is pumped into
the knee through one incision to expand it and to wash blood from the area.
This allows the doctor to see the knee structures more clearly.

The surgeon inserts an arthroscope into one of the other incisions. A
camera at the end of the arthroscope transmits pictures from inside the knee to
a TV monitor in the operating room.

Surgical drills are inserted
through other small incisions. The surgeon drills small holes into the upper
and lower leg bones where these bones come close together at the knee joint.
The holes form tunnels through which the graft will be anchored.

If you are using your own tissue, the surgeon will make another incision in the knee and take the graft (replacement tissue).

The graft is pulled through the tunnels
that were drilled in the upper and lower leg bones. The surgeon secures the
graft with hardware such as screws or staples and will close the incisions with stitches or
tape. The knee is bandaged, and you are taken to the recovery room for 2 to 3

During ACL surgery, the surgeon may repair other injured
parts of the knee as well, such as
menisci, other knee ligaments,
cartilage, or broken bones.

What To Expect After Surgery

Arthroscopic surgery is often done on
an outpatient basis, which means that you do not spend a night in the hospital.
Other surgery may require staying in the hospital for a couple of days.

You will feel tired for several days. Your knee will be swollen, and you may have numbness around the cut (incision) on your knee. Your ankle and shin may be bruised or swollen. You can put ice on the area to reduce swelling. Most of this will go away in a few days, and you should soon start seeing improvement in your knee.

care for your incision while it heals, you need to keep it clean and dry and
watch for signs of infection.

Physical rehabilitation after ACL
surgery may take several months to a year. The length of time until you can
return to normal activities or sports is different for every person. It takes most people at least 6 months to return to activity after surgery.footnote 2

Why It Is Done

The goal of ACL surgery is to restore
normal or almost normal stability in the knee and the level of function you had
before the knee injury, limit loss of function in the knee, and prevent injury
or degeneration to other knee structures.

Not all ACL tears
require surgery. You and your doctor will decide whether rehabilitation (rehab) only or
surgery plus rehab is right for you.

You may choose to
have surgery if you:

  • Have completely torn your ACL or have a partial
    tear and your knee is very unstable.
  • Have gone through a
    rehab program and your knee is still unstable.
  • Are very
    active in sports or have a job that requires knee strength and stability (such
    as construction work), and you want your knee to be as strong and stable as it
    was before your injury.
  • Are willing to complete a long and
    rigorous rehab program.
  • Have
    chronic ACL deficiency, which is when your knee is unstable and affecting your quality
    of life.
  • Have injured other parts of your knee, such as the
    cartilage or
    meniscus, or other
    knee ligaments or

You may choose not to have surgery
if you:

  • Have a minor tear in your ACL (a tear that can
    heal with rest and rehab).
  • Are not very active in sports
    and your work does not require a stable knee.
  • Are willing to stop
    doing activities that require a stable knee or stop doing them at the same
    level of intensity. You may choose to substitute other activities that don’t
    require a stable knee, such as cycling or swimming.
  • Can complete a
    rehab program that stabilizes your knee and strengthens your leg
    muscles to reduce the chances that you will injure your knee again and are
    willing to live with a small amount of knee instability.
  • Do not
    feel motivated to complete the long and rigorous rehab program
    necessary after surgery.
  • You have medical problems that make surgery too risky.

How Well It Works

A few people who
have ACL surgery still have knee pain and instability and may need another
surgery (revision ACL reconstruction). Revision ACL
reconstruction is generally not as successful as the initial ACL


ACL reconstruction surgery is generally safe.
Complications that may arise from surgery or during rehabilitation (rehab) and recovery

  • Problems related to the surgery itself. These
    are uncommon but may include:

    • Numbness in the surgical scar
    • Infection in the surgical incisions.
    • Damage to
      structures, nerves, or blood vessels around and in the knee.
    • Blood
      clots in the leg.
    • The usual risks of anesthesia.
  • Problems with the graft tendon (loosening,
    stretching, reinjury, or scar tissue). The screws that attach the graft to the
    leg bones may cause problems and require removal.
  • Limited range of
    motion, usually at the extremes. For example, you may not be able to completely
    straighten or bend your leg as far as the other leg. This is uncommon, and
    sometimes another surgery or manipulation under anesthesia can help. Rehab attempts to restore a range of motion between 0 degrees (straight) and 130
    degrees (bent or flexion). It’s important to be able to get your knee straight so you can walk normally.
  • Grating of the
    kneecap (crepitus) as it moves against the lower end of the thighbone (femur),
    which may develop in people who did not have it before surgery. This may be
    painful and may limit your athletic performance. In rare cases, the kneecap may
    be fractured while the graft is being taken during surgery or from a fall onto
    the knee soon after surgery.
  • Pain, when kneeling, at the site where
    the tendon graft was taken from the patellar tendon or at the site on the lower
    leg bone (tibia) where a hamstring or patellar tendon graft is
  • Repeat injury to the graft (just like the original
    ligament). Repeat surgery is more complicated and less successful than the
    first surgery.

What To Think About

In an avulsion fracture, repair
surgery is always done as soon as possible.

Current research on the
surgical treatment of ACL injuries includes different techniques and places to
attach grafts; different ways of securing the graft; different types of grafts, such as
tendon, muscle, or fascial grafts from your body (autograft); and grafts from a
donor (allograft). When choosing a graft, you and your doctor may consider the following:

  • Each type of graft and procedure has its own risks and benefits. Talk with your doctor about the type of graft and procedure that will be best for you.
  • The success of surgery may be more dependent on
    the surgeon’s skill and preference than the type of graft used.

Complete the surgery information form (PDF) (What is a PDF document?) to help you prepare for this surgery.



  1. Honkamp NJ, et al. (2010). Anterior cruciate ligament injuries in adults. In JC DeLee et al., eds., Delee and Drez’s Orthopaedic Sports Medicine: Principles and Practice, 3rd ed., vol. 2, pp. 1644-1676. Philadelphia: Saunders Elsevier.
  2. Micheo W, et al. (2015). Anterior cruciate
    ligament tear. In WR Frontera et al., eds., Essentials of Physical Medicine and Rehabilitation, 3rd ed., pp. 324-330. Philadelphia: Saunders.

Other Works Consulted

  • American Academy of Orthopaedic Surgeons (2014). Management of Anterior Cruciate Ligament Injuries: Evidence-Based Clinical Practice Guideline. Rosemont, IL: American Academy of Orthopaedic Surgeons. Accessed June 12, 2015.
  • McMahon PJ, et al. (2014). Sports medicine. In HB Skinner, PJ McMahon, eds., Current Diagnosis and Treatment in Orthopedics, 5th ed., pp. 88-155. New York: McGraw-Hill.


ByHealthwise Staff
Primary Medical Reviewer William H. Blahd, Jr., MD, FACEP – Emergency Medicine
Adam Husney, MD – Family Medicine
E. Gregory Thompson, MD – Internal Medicine
Kathleen Romito, MD – Family Medicine
Specialist Medical Reviewer Freddie H. Fu, MD – Orthopedic Surgery

Current as ofMarch 21, 2017

Honkamp NJ, et al. (2010). Anterior cruciate ligament injuries in adults. In JC DeLee et al., eds., Delee and Drez’s Orthopaedic Sports Medicine: Principles and Practice, 3rd ed., vol. 2, pp. 1644-1676. Philadelphia: Saunders Elsevier.
Micheo W, et al. (2015). Anterior cruciate
ligament tear. In WR Frontera et al., eds., Essentials of Physical Medicine and Rehabilitation, 3rd ed., pp. 324-330. Philadelphia: Saunders.