An ACL tear in an injury to the anterior cruciate ligament (ACL) inside your knee joint. It usually happens during sports that involve sudden stops and changes in direction, like basketball, soccer, football, tennis, volleyball, and skiing. Women are more likely to have an ACL tear than men.

A tear can be partial or complete. ACL tears often happen along with other injuries, like MCL tears.

Many people hear or feel a “pop” in their knee when an ACL injury occurs. Other symptoms include:

• Swelling that usually gets worse for hours after the injury.
• Pain, especially when you try to put weight on the injured leg.

If the tear is mild, you might only notice that the knee feels unstable.

Treatment depends on how bad the ACL tear is and how active you are. Young athletes usually need surgery to safely return to sports. Older, less active people usually don’t need surgery.

Treatments include:

• Crutches and, sometimes, a knee brace, to stop you from putting weight on your leg and keep the knee stable while it heals.
• Physical therapy, as a treatment or after surgery, to restore function to your knee and strengthen and stabilize the leg muscles that support it.
• Surgery, usually arthroscopic, to replace or rebuild the torn ligament. The surgeon replaces the torn ACL with a piece of tendon from another part of your knee or leg. Sometimes, a tendon from a donor is used.
• Arthroscopic surgery is a minimally-invasive surgery. Done through a few small incisions, this helps you heal faster and with less pain.
• Occasionally, the surgeon can stitch the ACL tear back together instead of replacing it.