The patient’s shoulder is wide on one side and narrow on the other side for the following common reasons: First, shoulder trauma: such as shoulder fracture can lead to local fracture deformity. If timely repositioning and fixation is not performed, after the deformity heals, it will make that side of the shoulder joint significantly wider. Taking X-rays can reveal the extent of the lesion and early surgical treatment can prevent the occurrence of symptoms, or if local bony deformity healing has occurred, surgical treatment is required. Secondly, periarthritis of the shoulder joint: it will affect the range of motion of the shoulder joint, causing the patient to have limited movement of the shoulder joint. Long-term inability to move normally will lead to secondary atrophy of the muscles around the shoulder joint on that side, resulting in narrowing of the shoulder. Therefore, one side of the shoulder must be diagnosed early and treated early in order to get quick relief of clinical symptoms and avoid serious dysfunction and shape changes.