This is a tear of a large tendon in the front of your knee. We call it the "patellar tendon." It connects the bottom of the kneecap to the top of the shinbone. It helps you straighten your leg. You can have a tear that doesn't go all the way through the tendon, or you can tear the tendon completely. A complete tear is a disabling injury.
You can tear your patellar tendon if the front of your knee is hit very hard. That can happen during a fall. You can also tear this tendon with forceful jumping. Your tendon is more likely to tear if it's already weak because of chronic disease, medications or a previous injury.
A patellar tendon tear is a painful injury. It can make it hard for you to straighten your leg, and hard for you to walk. You may have bruising and cramping. With a complete tear, you may feel a popping sensation. Your kneecap may slide up above your knee.
Treatment depends on how badly you've torn the tendon. A small tear may heal if you wear a brace to keep your knee from moving and if you have physical therapy. A complete tear can be repaired with surgery. Your healthcare provider can create a plan that's right for you.