Many patients have the question, “Why did my shoulder dislocate? Will it dislocate again in the future?” . Most of these patients we encounter in the clinic are in their twenties or thirties, and some are in their forties. In some cases, the shoulder dislocation occurred after trauma or strenuous exercise, and in some cases, the shoulder dislocated in their sleep. All of these patients face the same problem – a recurrence of shoulder dislocation. Why does this happen? The shoulder joint is a very special joint in the human body. The shoulder joint in the narrow sense refers to the glenohumeral joint, which consists of the humeral head and the scapular glenoid and is the joint with the largest range of motion in the human body. Since the diameter of the humeral head is much larger than the scapular glenoid and the scapular glenoid fossa is very shallow, the glenohumeral joint formed by the humeral head and scapular glenoid is like a seal with a ball on top of its nose, with a small nose (small scapular glenoid area) and a large ball (large humeral head). On the one hand, this joint structure gives the shoulder joint great mobility, allowing it to perform many complex functions; on the other hand, it also makes the shoulder joint very unstable and prone to dislocation when the surrounding structures are relaxed or traumatically injured. The mechanisms that maintain the stability of the shoulder joint are very complex, but simply put, its stability is maintained by both static and dynamic stabilization structures. The static stabilizing structures are mainly composed of the glenoid labrum, glenohumeral ligament complex and joint capsule; the dynamic stabilizing structures are mainly composed of the muscles surrounding the shoulder joint, such as the rotator cuff. When the shoulder joint moves, these structures precisely maintain the humeral head in the scapular glenoid fossa under neurological regulation, which both perform the function of the shoulder joint and do not cause shoulder instability. When trauma and other factors disrupt these shoulder joint stability structures, dislocation of the shoulder joint may occur. Most shoulder dislocations are anteriorly oriented, and their recurrence rate is closely related to the patient’s age and occupation. Studies have reported that the recurrence rate of shoulder dislocation is as high as 90% in patients under 20 years of age, while the recurrence rate is much lower in patients over 40 years of age, at 10%, but patients in this age group are prone to rotator cuff injury. The reasons for this are that younger patients need more violence to dislocate the shoulder joint, which is more destructive to the shoulder joint and leads to serious damage to the stable structure of the shoulder joint, which may be one of the reasons; in addition, younger patients love sports, which increases the chance of shoulder dislocation; finally, some special groups, such as gymnasts, swimmers, tennis players, etc., have a special need for shoulder joint activities, and the ligament structure of the joint becomes more lax to adapt to their functional needs. Finally, in some special groups, such as gymnasts, swimmers, tennis players, etc., the ligamentous structure of the joint becomes more relaxed to meet their functional needs, and the high-intensity sports put the shoulder joint in a more unstable state, which leads to recurrence of shoulder dislocation.