Protruding shoulder bones may be caused by the following reasons: 1. It may be caused by the patient being too thin. This is often seen when the patient is severely malnourished or has anorexia or excessive weight loss. In this case, the subcutaneous fat becomes much thinner, making the bony prominence of the shoulder particularly prominent. 2. It may be due to genetic factors. Some patients have a large skeleton due to hereditary reasons, and when they are thin, the bones in their shoulders will become more prominent. 3. There may be the effect of old injuries. If there is an old fracture of the shoulder joint or a dislocation of the acromioclavicular joint or other diseases, you will see a very obvious bony protrusion in the shoulder. 4. There may be scoliosis. In some patients with scoliosis, the shoulder may be uneven on both sides, and one side of the shoulder may protrude upward or outward, and a bony protrusion may be visible on the surface.