Why does patellar dislocation cause kneecap pain?

A dislocation can stretch the capsule and ligaments that help guide the kneecap. The joint lining may become irritated, and swelling can build up inside or around the knee. Pain is often felt at the front of the knee and may increase when bending, straightening, or putting weight through the leg. A small area of cartilage or bone can also be injured during the movement, so an examination is needed even if the kneecap returns to place on its own.

Stop the activity and keep the leg in a comfortable position. Avoid trying to force the kneecap back or repeatedly testing the movement. A cold pack wrapped in cloth may ease discomfort for short periods. Arrange prompt medical assessment; a clinician may check alignment, swelling, stability, and movement, then recommend support, exercises, or imaging depending on the findings. Use only pain relief that is suitable for you and follow its label or a clinician’s advice.

Seek urgent care if the knee looks out of place, cannot be moved, becomes rapidly swollen, or the foot feels numb, cold, or unusually pale. Immediate assessment is also needed after a forceful injury when you cannot stand or take a few steps. These signs can point to a continuing displacement, fracture, or problem affecting nerves or blood flow.

Ask whether the kneecap is stable, whether cartilage or bone may have been injured, and which movements should be limited. You can also ask when to begin rehabilitation, whether a brace is appropriate, and which symptoms should prompt another review.