If you have a torn anterior cruciate ligament (ACL) and reconstruction has been recommended, it is natural to wonder what actually happens during the operation. ACL reconstruction is a procedure in which the damaged ligament is replaced with a tendon graft to restore stability to the knee.
The surgery is usually performed using arthroscopic techniques, which involve a small camera and specialized instruments inserted through small incisions around the knee. The surgeon first examines the joint, addresses any associated injuries when necessary, and then positions and secures the new graft where the ACL normally functions.
What Happens Before ACL Reconstruction?
Before surgery, your orthopedic specialist evaluates the knee to confirm the extent of the ACL injury and identify any other problems that may need attention during the operation. This assessment may include:
- A physical examination of knee stability and movement
- MRI or other imaging to assess the ACL and associated structures
- Evaluation of the meniscus, cartilage, and other knee ligaments
- Assessment of swelling and range of motion
- Discussion of your activity level, work, sports, and recovery goals
*AI-generated image - for illustration only. Clinical accuracy is not guaranteed.
In some cases, rehabilitation begins before surgery to reduce swelling and improve knee movement and muscle control. The exact preparation depends on the condition of your knee and the planned procedure.
Step-by-Step: How ACL Reconstruction Is Performed
1. Anesthesia Is Administered
ACL reconstruction is performed under anesthesia so that you remain comfortable during the operation. General anesthesia or regional anesthesia may be used depending on your health, the surgical plan, and the anesthesiologist's assessment. Your vital signs are monitored throughout the procedure.
2. The Surgeon Examines the Knee With an Arthroscope
Most ACL reconstructions are performed arthroscopically. The surgeon makes small incisions around the knee and inserts an arthroscope, a thin instrument with a small camera.
The camera provides a magnified view of the inside of the joint on a monitor. This allows the surgeon to assess the ACL and inspect other structures, including the menisci and articular cartilage.
*AI-generated image - for illustration only. Clinical accuracy is not guaranteed.
3. Associated Knee Injuries Are Treated When Necessary
An ACL tear can occur along with other injuries inside the knee. A torn meniscus, for example, may be present at the same time. If an associated injury requires treatment, it may be addressed during the same operation.
Depending on the injury, this could involve repairing a meniscus or treating damaged tissue. Not every associated injury requires surgery, so the additional procedures performed are individualized.
4. The Tendon Graft Is Prepared
The replacement ACL is made from a tendon graft. When the patient's own tendon is used, it is called an autograft. Common autograft sources include:
- Patellar tendon
- Hamstring tendons
- Quadriceps tendon
5. The Torn ACL Area Is Prepared
The surgeon prepares the area where the damaged ACL was located. Unstable or damaged tissue that interferes with reconstruction may be removed, while suitable tissue may be preserved when appropriate. The aim is to create a suitable environment for positioning the new graft while protecting the surrounding structures.
6. Bone Tunnels Are Created
Small tunnels are carefully created in the thighbone (femur) and shinbone (tibia). These tunnels correspond to the areas where the ACL normally attaches to the bones.
The position of these tunnels is an important part of the operation. Accurate placement allows the graft to function in a way that more closely reproduces the stabilizing role of the original ACL.
7. The Graft Is Passed Into Position
The prepared tendon graft is passed through the bone tunnels and positioned inside the knee. The surgeon checks its position, length, and tension to ensure that it can provide appropriate stability while allowing the knee to move through its intended range.
8. The Graft Is Fixed in Place
Once the graft is correctly positioned, it is secured to the femur and tibia using fixation devices. The specific fixation method depends on the graft and surgical technique.
The surgeon then checks the knee's movement and stability to make sure the reconstructed ligament is functioning appropriately.
9. The Incisions Are Closed
After the reconstruction and any additional procedures are completed, the arthroscopic instruments are removed and the small incisions are closed.
A dressing is placed over the surgical sites. Depending on the procedure and postoperative plan, a knee brace may also be used.
How Long Does ACL Reconstruction Surgery Take?
The operation itself commonly takes around one to two hours, although the exact duration varies. Surgery may take longer when additional procedures are required, such as treatment of a meniscus injury or another ligament problem.
The total time spent at the hospital or surgical facility is longer than the operating time because it includes preparation before surgery and monitoring during recovery from anesthesia.
What Happens Immediately After Surgery?
*AI-generated image - for illustration only. Clinical accuracy is not guaranteed.
After the operation, you are moved to a recovery area where your condition is monitored as the effects of anesthesia wear off.
Many ACL reconstruction procedures can be performed as day-care surgery, allowing suitable patients to return home the same day. Whether this is appropriate depends on your overall health, pain control, mobility, and whether additional procedures were performed.
You may initially need crutches, and your orthopedic team will provide instructions about weight-bearing, exercises, wound care, medication, and follow-up.
Why Does Rehabilitation Start After Surgery?
ACL reconstruction creates a new ligament, but the knee still needs time and rehabilitation to regain normal function. Early rehabilitation generally focuses on controlling swelling, restoring knee movement, activating the muscles around the knee, and gradually improving strength.
As recovery progresses, rehabilitation may include balance exercises, coordination training, functional movements, and sport-specific exercises when appropriate.
*AI-generated image - for illustration only. Clinical accuracy is not guaranteed.
Return to demanding physical activity should depend on functional recovery, strength, stability, and movement quality rather than simply the amount of time that has passed since surgery.
What Can Affect the Surgical Plan?
Although the basic principles of ACL reconstruction are similar, the exact procedure is not identical for every patient. The surgical plan may be influenced by:
- The type and extent of ACL tear
- The presence of meniscus or cartilage injuries
- Other damaged knee ligaments
- Age and skeletal maturity
- Activity and sports requirements
- Previous knee surgery
- The selected graft
- The surgeon's assessment of the knee
This is why two people undergoing ACL reconstruction may have slightly different surgical and rehabilitation plans.
What Are the Possible Risks of ACL Reconstruction?
Like any surgery, ACL reconstruction carries potential risks. These may include infection, bleeding, blood clots, knee stiffness, persistent pain, numbness around the incision, problems at the graft-harvest site, graft failure, or continued instability.
There can also be risks related to additional procedures performed during the same operation. Your individual risk depends on factors such as your overall health, the nature of the knee injury, graft choice, surgical technique, and rehabilitation.
The Bottom Line
ACL reconstruction involves replacing a damaged ACL with a tendon graft and positioning that graft so it can restore stability to the knee. The procedure generally involves arthroscopic examination of the joint, treatment of associated injuries when necessary, preparation of the graft, creation of bone tunnels, graft placement and fixation, and closure of the small incisions.
The operation is only one part of treatment. A structured rehabilitation program is essential for restoring knee movement, strength, coordination, and functional stability.
The exact surgical technique, graft choice, additional procedures, and rehabilitation plan are individualized according to the patient's injury, physical requirements, and overall treatment goals.
*AI-generated image - for illustration only. Clinical accuracy is not guaranteed.
