All Health Topics

Patella dislocation

Published July 2, 2016
• Reviewed by Matthew J. Bollier MD, FAOA
on Oct. 1, 2019

What is a patella dislocation?

The patella (also commonly known as the kneecap) is the bone that covers the front of your knee joint. When your knee is fully straightened and the muscles around it are relaxed, your kneecap can slide a little from side to side. A dislocated kneecap moves farther than normal, usually toward the outside of the knee.

Patella dislocation symptoms

Symptoms of kneecap dislocation:

  • Pain and swelling in your knee
  • Your knee appears to be deformed
  • Your knee cannot be straightened as far as normal
  • Your kneecap slides farther from side to side than usual

If your kneecap gets dislocated frequently, you may not feel as much pain after the first few times it happens. You should still have the knee examined by a doctor, because kneecap dislocation causes damage to the knee joint, even when it doesn’t hurt.

Patella dislocation causes and risk factors

Playing a sport that requires you to change directions quickly, like tennis or basketball, can put you at risk for a kneecap dislocation. Causes include:

  • A sudden change in direction while your leg is planted
  • A direct hit to your knee by the ground or by another person

Patella dislocation treatment options

If your kneecap is dislocated but there is no other damage to your knee joint, you may not need surgery. Your doctor may instead recommend putting your knee in a cast to keep it from moving while it heals.

If there is other damage to the bone or cartilage in the knee, your doctor may choose to treat your dislocated kneecap with surgery.