The shoulder joint is the largest and most flexible joint in the body in terms of range of motion. The shoulder joint has very little bony restriction and relies heavily on the surrounding glenoid labrum, joint capsule, ligaments, tendons and the powerful numerous muscles to maintain the stability of the shoulder joint. I. Recurrent dislocation of the shoulder joint? 1. Causes: The vast majority of recurrent dislocations of the shoulder joint are caused after trauma. After the first dislocation, the glenoid labrum and/or capsular ligaments that maintain the stability of the shoulder joint are torn away. After the joint is repositioned, however, the avulsed glenoid labrum ligament tissue is difficult to restore to its original position, so the shoulder joint lacks a stable structure in front of it. Thereafter, each time the joint is moved to a certain angle, usually in an abducted external rotation position (similar to a throwing motion), a dislocation occurs, resulting in a recurrent dislocation of the shoulder joint. 2. Associated risk factors: It is currently believed that whether a shoulder dislocation becomes a recurrent dislocation is closely related to the age of the patient at which the dislocation first occurred. Age less than 20 years is a high risk factor. The risk of forming a recurrent dislocation is also high if the joint glenoid defect is relatively large or if the humeral head bone defect (Hill-Sachs) is severe after the injury. 3. Treatment: A dislocation of the shoulder joint that occurs more than once is known as a recurrent dislocation. Current studies have shown that the only possible cure is through surgical treatment. A small number of patients can limit their shoulder joint range of motion and stop moving after reaching a certain angle to avoid dislocation, but the level of motion is significantly reduced. 4.Surgical treatment methods: There are many treatment methods, which need to be evaluated according to the degree of injury and the patient’s activity level. Commonly used is minimally invasive arthroscopic treatment to re-suture the torn tissue for fixation. This requires a preoperative CT 3D reconstruction and MRI to fully assess the extent of glenoid labral and bony tissue damage. It should be noted that any treatment method carries the risk of recurrence. 5. Timing of surgical treatment: In case of recurrent dislocation, early treatment is recommended because the degree and extent of intra-articular damage may increase with the increase in the number of dislocations, which may affect the healing process. II. Glenoid labrum injury The main role of the glenoid labrum is to increase the stability of the shoulder joint, and the glenoid labrum is one of the common sites of intra-articular injury in the shoulder joint. After trauma, it can cause injury with corresponding symptoms such as pain, popping, interlocking, and shoulder instability. 1. Common sites of glenoid labrum injury: (1) Anterior inferior glenoid labrum injury: Commonly seen in recurrent dislocation of the shoulder joint, causing shoulder dislocation and instability. (2) SLAP (superior labrum anterior and posterior, SLAP): It is an avulsion above the glenoid labrum from anterior to posterior, involving the long head tendon attachment of the biceps. Mostly seen in throwing athletes. (3) Kim injury: refers to the posterior and posterior lower glenoid labrum injury. (2) Glenoid labrum injury presentation and diagnosis: Most patients with glenoid labrum injury are associated with pain, usually during shoulder motion, and can also present with symptoms such as strangulation, popping and instability. Diagnosis depends on history, symptoms and physical examination, and is more difficult compared to rotator cuff injury. Traditional X-rays, ultrasound, CT, MRI, etc. are difficult to diagnose glenoid labral injuries. MRI plus arthrography has improved the diagnostic rate. Treatment of glenoid labrum injury: Non-steroidal anti-inflammatory and analgesic drugs and rest can be used to reduce the symptoms of the shoulder joint, and rehabilitative training methods can be developed according to the location of the glenoid labrum injury. If these methods are not effective, shoulder arthroscopy should be considered. Shoulder arthroscopy remains the most effective method to clearly diagnose glenoid labrum injury, and depending on the intraoperative situation, cleanup or repair surgery is performed at the same time.