The function of the shoulder joint is directly related to our quality of life, and problems are most likely to directly affect our daily life, such as mild soreness and pain, gradual stiffness and restriction, and tiredness in wear; serious repeated dislocation, popping and interlocking, and afraid to exercise; even sleepless nights, weakness and severe pain, and mental anxiety. With the aging of the population, the number of people with shoulder pain is increasing. ”If the dry axis does not move, the avenue is cool; if the kun axis does not move, all things perish; if the shoulder axis does not move, there is no humanity.” As we all know, the shoulder joint is the most flexible joint in the human body, with several dimensions to reach 180°. Therefore, this “axis” of the shoulder joint is unique to human beings, and even if we no longer use it to leap through the forest, we still have to use it to carry the force. Age and trauma are the two main enemies of the shoulder joint. First of all, by age, the shoulder joint is most prone to dislocation in the late teens and early twenties, and habitual dislocation (called recurrent dislocation in technical terms) occurs in the vast majority of cases at this age. There have been breakthroughs in the diagnosis and treatment of this disease, and timely and regular treatment (most of which can be minimally invasive) can achieve excellent results. Shoulder pain in the 30s and 40s after strenuous exercise, usually glenoid labral injury, impingement, etc., can also be diagnosed and treated early. When you reach the age of 50, especially women with endocrine disorders such as diabetes, you are most likely to get “fifty shoulder”, which is called “primary frozen shoulder” or “frozen shoulder” in professional terminology, or “frozen shoulder” in common people. “(All other shoulder pain is not frozen shoulder). The disease is characterized by progressive shoulder pain with activity limitation without any trauma or other causes. Shoulder pain in the 60s and 70s is usually caused by rotator cuff injury, which is a tendon tear of the 4 core muscle groups of the shoulder joint due to aging, degeneration and ischemia. Next is trauma. Trauma in young age can cause joint dislocation, glenoid labrum injury, acute rotator cuff injury, etc., which can affect the function and quality of life of the shoulder joint if not treated in time. However, because of the degeneration and fragility of the rotator cuff tissue, dislocation can easily cause rotator cuff tears. In addition to rotator cuff tissue lesions, osteoporosis is usually combined, and shoulder fractures are common after a fall, while simple fractures can be better repositioned and fixed. The following cases are very difficult to manage and are a “nightmare” for every patient and a “hard bone” for every orthopedic surgeon: 4-part fracture of the proximal humerus (crushed and separated proximal humerus) in elderly patients; combined with Comminuted proximal humerus fractures with significant rotator cuff injury; rotator cuff tears with arthrosis; large rotator cuff tears with pseudoparesis; irreparable rotator cuff tears; failed primary shoulder replacements; failed internal fixation of proximal humerus fractures; old fixed shoulder dislocations; tumors of the proximal humerus; etc. As doctors who specialize in the shoulder joint, we have the courage and confidence to face all kinds of complex shoulder joint disorders and overcome each hurdle. Reverse shoulder joint replacement (also called reverse shoulder joint, reverse shoulder, reverse ball shoulder joint, etc.) has become the “grand finale” for shoulder surgeons with the continuous improvement of prosthesis design and shoulder surgery techniques. This type of prosthesis has the “head on top, glenoid on the bottom” in the opposite direction of our real shoulder joint. By this design, the center of rotation of the joint is shifted downward and inward, the concave joint surface is supported and the convex joint surface is weight bearing, allowing the deltoid muscle to directly drive the shoulder joint. The application of this prosthesis can help us to overcome the above mentioned problems and bring a blessing to the above mentioned patients who are suffering, and make the patient’s delicate shoulder joint “Jin Shaft”. Here is our case: The patient is a 74-year-old female with a 4-part fracture of the proximal humerus with dislocation, rotator cuff injury and osteoporosis. The humeral head and neck were completely fractured and separated, and the large tuberosity was as thin as an eggshell, which could not be effectively fixed by internal fixation; the large and small tuberosities were separated, exposed, and then the power lines were threaded around the bone in the upper and middle parts of the subscapularis tendon and the infraspinatus tendon, respectively, for repositioning and tying the prosthesis after installation (this part is time-consuming and must be carefully done), and the height of the distal prosthesis installation needed to be predetermined; the glenoid was exposed, the glenoid lip and the long head tendon stump were removed, and the joint surface was tilted vertically and slightly downward. Grinding of the articular surface; vertical installation of the glenoid not base, 3-4 screws fixed, all pointing to the rostral process; anti-ball head trial mold and proximal shank trial mold, determine the ball size (generally 38), shank height and glenoid surface liner thickness; finally is the bone cement installation of the distal shank, pay attention to the posterior tilt angle 0-20 degrees; finally determine the liner height again, installation of the official prosthesis, anti-shoulder joint should be tight rather than loose, the joint tendon has a certain tension as well as The more difficult to reposition is the reference.