What causes clicking of the knees in your 12 year old son?

Clicking in the knees of a 12-year-old can be caused by several factors, including growth-related changes, ligament laxity, or the movement of tendons and ligaments over bony structures. It may also occur due to minor issues such as air bubbles in the joint fluid or normal variations in joint mechanics. While it's often harmless, if the clicking is accompanied by pain, swelling, or instability, it’s advisable to consult a healthcare professional for further evaluation.