Knee bending sound may be some physiological phenomenon, may also be the manifestation of certain diseases, such as meniscus injury, osteophytes, etc., should be timely consultation to find out the cause of the disease. 1. Physiological factors: due to joint activities caused by tendons sliding over the surface of bone tissue popping, but also some patients are due to the friction of the articular cartilage and meniscus, generally belong to the normal physiological phenomenon. 2. Pathological factors (1) Meniscus injury: such as meniscus tear, resulting in misalignment of the popping sound, this popping sound will have the feeling of joint strangulation, when walking, suddenly the leg is stuck, can not move, need to be in place to release the activities to continue to walk, and sometimes there is the feeling of playing soft legs. (2) osteophytes: knee long bone spurs, bending joints will sound, consider may be long-term standing or a posture caused by too long, will lead to muscle pulling, long-term will form bone spurs. Knee bending will pop may also be caused by other factors such as patellar subluxation, etc. It is recommended to consult a doctor in time to clarify the cause of the disease and give targeted treatment.