There are many reasons for the rattling sound at the joints of arm movement, which may be related to physiological popping, degenerative osteoarthritis, shoulder joint instability and other factors. 1. Physiological popping sound: may be a long time in a fixed static state, suddenly stretching or curved joints, will issue a crisp sound, is a normal physiological phenomenon, generally no other discomfort. 2. Degenerative osteoarthritis: When degenerative osteoarthritis occurs in the arm joints, the articular cartilage becomes rough because of wear and tear, and it will emit a rattling sound when the joints are in motion, accompanied by joint pain and symptoms such as restricted activities. 3. Shoulder instability: if the shoulder joint is congenital instability or habitual dislocation, the ligaments around the joint are loose, which can lead to rattling sound when the arm moves and accompanied by symptoms of shoulder pain. Rattling sound at the joint of arm movement can also be seen in other reasons, it is recommended that patients seek medical advice in time, follow the doctor’s instructions for relevant examinations, with the help of the doctor to clarify the cause, and targeted treatment or therapy.