Knee popping occurs when the knee joint moves, which is usually indicative of popping knee. Popping knee is usually directly related to the meniscus, and can be seen in both meniscus deformity and meniscus injury. Most of the knee popping caused by meniscus deformity is seen in discoid meniscus, which often leads to obvious popping of the knee during activities. For discoid meniscus, if the popping is very obvious and affects the patient’s activities, most of the knee popping can be considered to be corrected by surgery. Chronic strain of the meniscus or damage to the meniscus may cause the knee to pop when the knee is moved, often because the knee touches the damaged meniscus when doing a particular task. Knee popping can also be seen in physiological popping, mostly seen in middle-aged and old people, because with the age of muscle, ligament laxity, often in the activities of the knee joint when the joint capsule laxity and triggered by the joint popping, most of the popping is a kind of physiological popping, does not represent any pathological significance.