ACL Surgery: What to Expect

ACL injuries are common among people who play sports. The ACL (anterior cruciate ligament) is a band of tissue within the knee. It gets damaged when it stretches or tears. This can happen if you turn sharply or move suddenly while you’re running or jumping.

When your ACL is healthy, it helps to hold together the bones of your knee. It also helps to keep your knee stable. If it gets damaged, you may have trouble putting pressure on your knee, walking, or playing sports.

If you strain or slightly tear your ACL, it may heal over time with your doctor’s help and physical therapy. But if it’s completely torn, you may need to have it replaced -- especially if you’re young and active or an athlete who wants to keep playing sports. If you’re older or less active, your doctor might recommend treatments that don’t require surgery.

What Happens During the Operation?

Your doctor will remove the torn ligament from your knee and replace it with new tissue. The goal is to get your knee stable again and give it the full range of motion it had before you got hurt.

Doctors typically use arthroscopic surgery on your ACL. This means they insert tiny tools and a camera through small cuts around your knee. There’s less scarring of the skin with this method than with open-knee surgery.

How Does It Work?

Once your doctor removes your torn ACL, he puts a tendon in its place. (Tendons connect muscle to bone.) He may take a tendon from elsewhere in your body (like your knee, hamstring, or thigh) during surgery. Or he may use one from a deceased donor. Both types work well. When the tendon is placed within your knee, it’s known as a graft.

Your doctor will place the graft at the right spot, and he’ll drill two holes, called “tunnels.” He’ll drill one in the bone above your knee and another in the bone below it. Then, he’ll place screws in the tunnels and anchor the graft in place. It serves as a sort of bridge that a new ligament will grow on as you heal. It can take many months for a new ACL to grow in fully.


After surgery, your doctor will have you stay off your leg, rest your knee, and wear a brace to protect the joint.

Doctors are involved in ongoing research to see if a new type of ACL surgery is better than the standard care. It’s called Bridge-Enhanced ACL Repair (BEAR).

Unlike standard ACL surgery, BEAR helps the torn ACL heal itself so it doesn’t need to be replaced. Doctors insert a special tiny sponge into your knee between the torn ends of the ACL. They then inject the sponge with your own blood and stitch the loose, torn ends of the ACL into the sponge that contains the blood. It becomes a support for the ACL. Over time, the torn ends heal and become new, healthy ACL tissue.

What Can I Expect After Surgery?

The procedure takes about an hour. You’ll receive general anesthesia so you won’t feel or remember the surgery. Most people are able to go home the same day.

You’ll probably have to use crutches to keep the pressure off your knee. Before you leave the hospital, you’ll learn how to change the dressing on your wound. You may be told to keep your knee raised on pillows, put ice on it, and wrap it in an ace bandage to keep it compressed.

As your ACL begins to heal, your doctor should send you for physical therapy. That’ll help to strengthen the muscles and ligaments. After that you should be back to doing to the things you like to do within a few months.

WebMD Medical Reference Reviewed by Tyler Wheeler, MD on December 18, 2018



American Academy of Orthopaedic Surgeons: “ACL injury: Does it require surgery?” “Anterior Cruciate Ligament (ACL) Injuries.”

Mayo Clinic: “ACL Injury Overview,” “ACL Reconstruction: What You Can Expect.”

Emory Healthcare: “ACL Reconstruction.”

Boston Children’s Hospital: “Bridge-enhanced ACL Repair Clinical Trial Overview.”

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