Knee generally refers to the knee joint, knee popping patients, clinically seen, the cause of physiological factors and pathological factors, pathological factors are divided into meniscus lesions, senile osteoarthritic degeneration, lateral instability of the knee, synovial lesions of the knee and other reasons. 1. Physiological factors: usually there are no symptoms of localized pain, and the sound of knee joint popping is relatively crisp. Knee pain episodes will not be particularly frequent, mostly occurring in young adults, young adults, the joint capsule of the knee joint is relatively loose, and activities caused by negative pressure. 2. Pathological factors (1). Meniscus lesions: due to meniscus injury, congenital discoid meniscus patients, often flexion of the joint, the knee joint will occur larger popping sound. (2). Age-related osteoarthritic degeneration: due to the damage of the cartilage surface in old age, patients sometimes experience a significant popping sound when the joint is squatted. (3). Lateral knee instability: the patient may have a distinct popping sound on the lateral side of the knee joint during the process of the knee joint going from a flexed state, to a straightened state. (4). Lesions of the synovial membrane of the knee joint: synovial inflammation of the knee joint caused by a variety of reasons may also have a ringing sound above the knee joint. If the symptoms continue to be unrelieved, you should go to the hospital in time, and standardize the treatment under the guidance of the doctor.