When you experience a blow to the knee, there are several different injures that can occur—sometimes all at once. These can include a torn meniscus, a torn anterior cruciate ligament (ACL)…or a dislocated kneecap.

See What Is a Dislocated Kneecap?

The kneecap—also known as the patella—sits snugly on the front of the knee in a groove on the femur (thigh) bone. It’s held in place by ligaments and tendons.

The kneecap, or patella, sits in a groove in femur. Read Guide to Knee Joint Anatomy

But a traumatic blow to the knee can force the kneecap out of place. This is more likely to happen to women, those who are tall, or athletes who play a contact sport such as soccer, football, or lacrosse.

See Causes and Risk Factors for Dislocated Kneecaps

So how do you know if a knee injury involved a dislocated kneecap? It may have if these occur after a traumatic blow to the knee:

  • Your kneecap is out of place on the knee or even outside the knee, on the side of the leg
  • Your kneecap is painful to the touch
  • You can’t straighten your leg
  • Your leg is unstable or gives way
  • Your kneecap is tender, swollen, or bruised
  • You have sharp pain on the front of your knee when standing

Read a complete list of dislocated kneecap symptoms

Sometimes a knee that is dislocated while it’s flexed will move back into place on its own as the leg is straightened. Then it can be treated with the standard RICE protocol to ease pain and inflammation. A brace or cast may also be helpful to immobilize the kneecap while it heals.

See Treatment of Dislocated Kneecaps

If the kneecap remains out of place, the doctor may try to manually move it back. If it’s a severe dislocation and/or nearby soft tissues like tendons or ligaments have also been damaged and need repair, surgery is also an option.

See Surgery for Dislocated Kneecaps

Learn more:

What to Do When an Acute Patellar Injury Is Suspected

Symptoms of an Acute Patellar Injury