Shoulder creaking may be caused by several reasons: First, it may be caused by inflammation inside the shoulder joint, such as frozen shoulder, which may result in a series of sterile inflammatory exudates inside the shoulder joint, leading to significant pain, noise, and limited movement of the shoulder joint. Second, it may be caused by degeneration of the shoulder joint, such as osteoarthritis or other degeneration of the shoulder joint, which may cause the patient to have a strange sound when moving the shoulder. Third, it may be caused by injury to the shoulder joint, such as trauma to the tendons, joint capsule, bone and other structures inside the shoulder joint, which may cause abnormal movement of the shoulder and lead to abnormal noise.