Fracture and dislocation of sternoclavicular joint and medial clavicular bone are rare, accounting for 1.2~4% of shoulder joint injuries, while dislocations of sternoclavicular joint only account for 1% of total dislocations [1, 2]. Anterior dislocation of the sternoclavicular joint is significantly more than posterior dislocation, with a ratio of 20:1. The literature on posterior dislocation is mostly reported on individual cases, which is prone to misdiagnosis and missed diagnosis [3]. The sternoclavicular joint is the only joint connecting the upper limb to the trunk. It consists of the medial end of the clavicle, the clavicular trace of the sternal manubrium and the adjacent surface of the first costal cartilage .The complete ossification of the medial clavicular ossification center occurs at the age of 18–20 years and is not complete until the age of 23–25 years [4]. Due to the special anatomical characteristics, the injury of sternoclavicular joint in adolescents is often accompanied by medial clavicular fracture and posterior dislocation of sternoclavicular joint. The sternoclavicular joint is the most unstable joint in the whole body [4]. The articular surface of the medial end of the clavicle is inclined, 50% of the articular surface is in contact with the articular surface of the sternum, and there is a cartilage disc between the two articular surfaces. Despite this instability, sternoclavicular joint is rarely dislocated, and its stability is mainly protected by anterior and posterior sternoclavicular ligaments, costoclavicular ligaments, and interclavicular ligaments [4, 5]. Posterior dislocation of sternoclavicular joint often occurs in motor vehicle accidents, indirect violence is rare. Direct force acts on the anterior medial clavicle, pushing the clavicle behind the sternum into the mediastinum. Forward shoulder compression and rotation can lead to posterior dislocation of ipsilateral sternoclavicular joint [6]. If the violence is increased, it may cause dislocation of ipsoclavicular joint, which is prone to clinical misdiagnosis and missed diagnosis [7].