There are many reasons for mouth opening restriction, most of them are due to “irreducible displacement” of the articular disc, which is the most common problem for patients, and they often have significant mouth opening restriction, mouth deviation, facial pain, and changes in facial shape. Most of the patients in the clinic come to the clinic at this stage. Many of these patients have a history of joint popping, but at that moment when the joint does not open the mouth, it also occurs when the mouth is stuck, does not open to the maximum, and has painful opening. The term “irreducible displacement”, like “reducible displacement”, describes the relationship between the position of the articular disc during mouth opening and closing, that is, the articular disc is displaced to the front of the condyle of the mandible, which impedes the movement of the joint during mouth opening, commonly known as “stuck”. Because there are ligaments behind the articular disc to restrict its excessive movement, the original normal up and down position relationship between the articular disc and the condylar process now becomes anterior-posterior relationship. The forward-moving articular disc restriction blocks the normal magnitude of forward sliding of the condylar process, and the opening of the mouth is restricted, and if you want to open it more, the condylar process wants to push the articular disc farther, which causes a great mechanical stress loaded on the ligaments behind the articular disc and causes pain. This is the main cause of restricted opening and pain. But “irreducible displacement” does not necessarily mean restricted opening and pain! Many people have a displacement of the articular disc, and the body slowly adjusts to it, so that the posterior ligaments of the articular disc lengthen adaptively, and thus do not prevent the condylar process from sliding to the front when opening the mouth, so the mouth opens normally, and there is no ligament irritation or pain, and there is no discomfort at all. This is very common, and a high percentage of normal people actually have a displaced disc. Many patients who present with limited opening and pain on one side and have an MRI that reveals the other side is also displaced, but never feel any discomfort, confirm this. Having introduced the concept of “irreducible displacement”, let’s move on to the treatment of patients with “irreducible displacement”. Rehabilitation is not just about physiotherapy and machines, but most of the rehabilitation departments in the region treat this disease by doing physiotherapy with machines. In China, our department provides comprehensive rehabilitation treatment for patients with all types of TMJ disorders, and we design individualized treatment plans for different patients and conditions. For patients with “irreversible displacement”, there is still a very high chance of “manual repositioning” within the early two months, which means that there is a hope for a complete restoration of the normal joint disc position, so the earlier the treatment, the better the results. Because the displacement is too long, the joint capsule and other soft tissues have already adhered to the contracture, there is almost no chance to reset, but can also restore normal function. Even if the patient is treated in our department at an early stage, it is not always possible to reset the joint, and not every patient who is “reset” can eventually maintain the normal position of the joint disc. In clinical practice, we do not pursue the “reset” of the patient, it is best to “reset” (shorter treatment time, immediate relief of opening restriction and pain), for patients who cannot be repositioned manually, the treatment of the rehabilitation department is to help the patient’s joint adapt to the new position, eliminate For patients who cannot be repositioned by manipulation, the treatment of the rehabilitation department is to help the patient’s joint adapt to the new position, eliminate the pain, restore the degree of opening and function, and help the patient improve the symptoms. Therefore, we should not blindly pursue repositioning, but should understand the treatment rationally, and should not simply think that “manual repositioning is very simple and applicable to everyone” and “only joint disc repositioning is really good”. The rehabilitation treatment is not only limited to the temporomandibular joint, there are many factors that contribute to the pathogenesis of this disease, including incorrect posture and psychological state, and the rehabilitation department tries its best to help patients correct and regulate them. Patients in the rehabilitation department should have the lowest recurrence rate because the treatment is done from the source of the disease. Many patients also have cervical spine problems, which is even one of the factors for the onset of the disease, and the rehabilitation department also deals with them together.