The different sizes of the clavicle may be related to the following reasons: 1. There may be some congenital hereditary factors, such as some patients have a family history or some birth injuries in the process of childbirth, which may cause bilateral clavicle asymmetry. 2. It may be caused by some old injuries of the clavicle. If there is some old fracture of the clavicle on one side, which leads to shortening and impaction of the fracture end. After its recovery, there may be bilateral clavicle asymmetry. 3, may be caused by scoliosis side. In the process of scoliosis, it may cause deformity of the thorax and upper limb bones, namely the clavicle and scapula, and then cause bilateral asymmetry. 4. It may be caused by long-term lateral lying or poor sitting posture to one side. These two conditions may cause the clavicle on one side to become shorter and more curved, and then make the bilateral asymmetry.