There are two main reasons for this condition: First, due to degeneration of the articular cartilage of the shoulder joint, there is osteophytes as well as calcification. When you lift your arm, there will be a popping sound due to the relatively large squeeze and friction between the humeral head of the shoulder joint and the joint pelvis. Because of the local inflammatory lesion, the inflammation will be stimulated when lifting the arm, and there will be obvious pain. Second, because there are muscle and soft tissue attachment points in the humeral tuberosity or other bony structures, if these attachment points are strained, strained, or cold, repeatedly a sterile inflammatory lesion will be formed locally, and after a long time, the soft tissue will become a hard fibrous hyperplasia, and after a long time, it will lead to local calcification and osteophytes, and when the activity is carried out, because the soft tissue elasticity The inflammatory lesions will be stimulated by the painful sensation as well, because the soft tissue elasticity decreases, the toughness decreases and becomes more fragile, and the bony structure will be plucked when moving.