This is called joint popping. Because of the joint activity, between the joint surface, cartilage pads and joint surface, tendons and joint capsule, tendons and bones, tendons and tendons, rubbing each other, will make a sound. This popping sound caused by the physiologic activity of the joints is known as physiologic popping. In most people, this sound is not obvious and cannot be heard, while in some people it is more obvious and can be heard more clearly. This is due to individual differences. Only popping, not accompanied by pain and activity disorders belong to the physiological popping.

Joint popping can also be pathologic, if the knee injury or older to exclude lesions caused by, then it is best to go to the hospital to see some insurance.