(HealthDay News) -- Your thighbone has a v-shaped notch that accommodates your kneecap. If the groove is too narrow or shallow, the knee cap can become unstable and dislocate.

The American Academy of Orthopaedic Surgeons says symptoms of an unstable kneecap include:

  • A buckling knee joint that can't support your weight.
  • A kneecap that seems to slide to the side during movement.
  • Pain in the front of your knee that worsens when you're moving.
  • Stiffness, swelling or pain when you sit down.
  • Cracking or creaking noises in your knee while you move.