(HealthDay News) -- Unstable kneecap occurs when the kneecap slides off the groove at the end of the thighbone.
The American Academy of Orthopaedic Surgeons says typical symptoms include:
- Buckling of the knee and inability to support body weight.
- Kneecap is located off to one side.
- Knee tends to catch when moved.
- Pain at the front of the knee that worsens when you're active.
- Stiffness or swelling in the knee, or pain when sitting.
- Knee makes a cracking or creaking sound when you move.