Knee creaking is called joint popping. Joint popping may be caused by physiological reasons such as normal popping and prolonged inactivity, or it may be caused by pathological factors such as osteoarthritis and trauma of the knee joint. 1. Physiological reasons: there is joint fluid in the normal knee joint, and there are many gas components in the joint fluid. When the joint is active, due to the increased pressure of the joint capsule, the gas is squeezed out of the joint capsule and ruptures, resulting in a popping sound, which is known as normal popping sound, and is a normal phenomenon. Prolonged inactivity will make the knee joint loose, and after re-exercise, the soft tissue and bone collide, and popping sound may also occur. 2. Pathological factors: when the knee joint develops degenerative diseases due to various reasons, it will lead to osteophytes and synovial hyperplasia, etc., which will cause abnormal impacts during activities, and popping sound may also occur, such as osteoarthritis of the knee and synovitis. When trauma causes soft tissue damage in the knee joint, it can lead to jamming of the soft tissue in the joint, and the above symptoms may also occur, such as meniscus injury, ligament injury, etc. Sometimes the cause of knee creaking symptoms can not be determined accurately, but also need to be combined with the characteristics of the medical history, other test results in order to make an accurate judgment, it is recommended to clarify the cause of the disease under the guidance of a doctor.