Shoulder rattling when shaking the arm, i.e., shoulder joint activity with popping sound, which is the sound of shoulder joint capsule, ligament, articular surface friction, etc. It may be a normal physiological state, or it may be pathologic, such as periarthritis, cervical-shoulder degeneration, trauma, etc. The causes can be divided into physiological and pathological. The reason why the shoulder rattles back and forth when shaking the arm can be divided into physiological and pathological, which are analyzed as follows: Physiological: the rattling of the shoulder bones is due to the shoulder joint activity, the gas in the joint cavity is squeezed and produced, if there is no other discomfort symptoms, it is a normal physiological rattling. In most people, this sound is very small and not easy to notice. Keep a posture for a long time, joint activity is less, more likely to appear popping. Pathological: If the shoulder pops back and forth when shaking the arm and is accompanied by pain and other uncomfortable symptoms, it can be considered to be caused by pathological reasons. 1. Shoulder joint ligaments and joint capsule of patients with frozen shoulder will have adhesion, leading to narrowing of joint space and abnormal friction of internal cartilage, thus causing shoulder bone ringing. 2. Degeneration of the neck and shoulder joints with osteophytes or bursa sclerosis, resulting in cartilage friction causing rattling, commonly seen in middle-aged and elderly patients. 3. Shoulder joint cartilage damage due to trauma, the formation of free body, when moving the joint rattling. When the shoulder rattles back and forth when shaking the arm and is accompanied by pain and other discomforts, it is recommended that the patient consult a doctor in time for a clear diagnosis so as to avoid delaying the condition.