Kneecap dislocation occurs when the kneecap is moved away from the position it is supposed to be in. The kneecap is held over the patellofemoral groove by tendons and ligaments, and if the knee is hit, usually by falling or banging into something, it can be knocked out of place. This can cause further injury by creating sprains, strains and tears to the ligaments.
As with any other type of knee injury, a kneecap dislocation comes with a great deal of pain. There is usually swelling around the knee, and in many cases there will also be bruising. The leg may feel unstable, like it is going to give out when weight is put on it. The knee can also look distorted because the kneecap is not where it should be. Anyone with these symptoms should seek immediate medical attention so the condition does not end up worsening over time. Long-term complications can arise if the injury is not properly treated, although sometimes, the kneecap will move back into place on its own. In the case that it does, it is still important to see your doctor and make sure that there is no permanent damage to the knee.