ACL Tear

The ACL, up close

The ACL (anterior cruciate ligament) is a tough band in the middle of your knee. It connects your thigh bone to your shin bone and stops your shin from sliding forward and twisting.

What a tear means

An ACL tear is when that band stretches too far and rips, partly or all the way through. Without it, the knee can feel loose and give way when you cut or pivot.

Myth or fact?

• A torn ACL usually heals back together on its own, like a scraped knee. Myth. The ACL has a poor blood supply, so it has a hard time healing inside the knee. That's why a torn ACL is usually rebuilt, not sewn back together.

Most happen without contact

About 7 out of 10 ACL tears happen with no one touching you. The usual moments: planting and cutting, stopping suddenly, or landing from a jump with the knee caving in.

The signs

Many athletes hear a pop. The knee usually swells within a day, and it can feel loose or give way. Some kids still have little pain and can walk on it, so get it checked.

Cutting and jumping sports

Soccer, football, basketball, gymnastics, lacrosse, and skiing see lots of ACL tears, because they're full of cuts, stops, and landings.

Other things that raise the risk

Weak hips and hamstrings, landing with stiff, straight knees, and having torn an ACL before all raise the chance of a tear.

Myth or fact?

• Female athletes are two to eight times more likely to tear their ACL than male athletes in the same sports. Fact. Differences in landing form, strength, and body shape all play a part. Prevention training helps a lot.
• Once you've torn your ACL and recovered, your chance of another ACL injury is the same as everyone else's. Myth. Young athletes who come back from an ACL tear have a higher chance of another one. Prevention training should continue.

Prevention programs work

Injury prevention warm-ups mix running, strength, jumping, and balance. Research shows this kind of training can lower ACL injury risk by as much as 72%, especially in teen girls.

Practice the safe landing

Land softly, bend your hips and knees, and keep your knees over your toes. Coaches use these exact tips in knee injury prevention programs.

Myth or fact?

• Prevention programs work best when you do them all season, not just once in a while. Fact. The benefit comes from doing them at least 2 to 3 times a week from preseason through the whole season, and again every year.

Getting checked

A doctor tests how stable the knee is and often orders an MRI scan to see the ACL. In growing kids, doctors use special methods that protect the growth plates.

Surgery and rehab

Many young athletes have surgery to rebuild the ACL. Then comes rehab: months of exercises to get back motion, strength, balance, and confidence.

Myth or fact?

• Being away from your sport after an ACL tear can make some athletes feel sad or down. Fact. Time away from your team can be hard. It's okay to talk about how you feel with a parent, coach, or athletic trainer.