When there is a protruding bone in the shoulder, it may be a normal bony prominence, or it may be a symptom caused by a space-occupying disease, acromioclavicular joint pathology, etc. 1. Normal bony prominences. Normal bony prominences, such as the acromion, scapular ridge, and acromioclavicular joint, may become more pronounced when one is thin or when one is doing a particular position or movement. 2. Caused by localized occupying disease. For example, if there are bony prominences in both shoulders and both sides are asymmetrical, it may be caused by localized bone tumors. 3. It may also be caused by bilateral acromioclavicular joint lesions. If there is a subluxation or inflammation of the acromioclavicular joints on both sides, it may cause an obvious bony protrusion, which may be mistaken for a new bone growing here. If the cause of the protruding bone in the shoulder is unknown, the patient should go to the orthopedic department of the hospital in a timely manner, and at the same time improve the necessary auxiliary examinations to clarify the cause of the disease and give targeted treatment to avoid delaying the disease.