If you can, straighten out your knee. If it is stuck and painful to move, stabilize (splint) the knee and get medical attention.
Your health care provider will examine your knee. This may confirm that the kneecap is dislocated.
A knee x-ray and, sometimes, MRIs should be done to make sure that the dislocation did not cause a broken bone or cartilage damage. If tests show that you have no damage, your knee will be placed into an immobilizer or cast to prevent you from moving it. you will need to wear this for several weeks (usually about 3 weeks).
After this time, physical therapy can help build back your muscle strength and improve the knee's range of motion.
If there is damage to the bone and cartilage, or if the kneecap continues to be unstable, you may need surgery to stabilize the kneecap. This may be done using arthroscopic or open surgery.