There may be the following reasons that can cause symptoms of protrusion of the bones above one side of a girl’s breast: 1. If the protrusion is located relatively close to the top of a woman’s breast, and this location is closer to the middle, it is likely that the symptoms of local protrusion are caused by the deformation of the rib cartilage. The rib cartilage itself is fibrocartilage, which has a certain degree of elasticity and a strong ability to change its shape. Once the rib cartilage on one side is subjected to a prolonged and repeated state of unilateral limb force, it can be deformed due to repeated forces, making the rib cartilage appear as if one side of the bone is protruding. In this case, there are no other accompanying symptoms, such as pain, redness, swelling, etc.; 2. If the protrusion is more upward and close to the location of the clavicle in the neck, it is likely to be a lesion of the sternoclavicular joint, which causes local protrusion. The sternoclavicular joint is a joint that can move, and habitual posture, habitual movements or limb exertion habits can stimulate the sternoclavicular joint and lead to joint swelling. If the swelling is prolonged, localized pain will occur.