Can your chin get rusty? Yes, it does. Many people usually encounter this situation in daily life: suddenly open your mouth wide, the jaw is like rust, can no longer be closed, once closed, the joint in front of the ear pain; or eating, talking, yawning, as long as the jaw moves, the joint in front of the ear will be like rust, a click sound, making people very uncomfortable. In fact, the crux of the problem lies in the “joint in front of the ear”. This joint is called the temporomandibular joint. The so-called “rusty” jaw is actually the TMJ “rusty”. The TMJ is a sliding joint and the synovial fluid is its important lubricant. When the synovial fluid decreases or disappears, the joint will become “rusty”. Therefore, the injection of hyaluronic acid gel or medical chitosan into the TMJ as a “lubricant” is one of the current treatments for TMJ disorders. Every time she opens her mouth, she makes a “clicking” sound. 28-year-old Hong has been married for 4 years and has been troubled by her “jaw disease”. Every time she opened her mouth, whether to eat or talk, the joints in front of her ears would make a “clicking” sound, and sometimes even painful, which not only made her embarrassed, but also painful. He came to our hospital and was diagnosed with Temporomandibular joint disorder (TMD). Now, Hong is receiving “conservative comprehensive” treatment: (1) injection of sodium hyaluronate gel into the TMJ cavity; (2) physiotherapy with infrared, laser and ultrasonic irradiation; (3) manual repositioning of the TMJ; and (4) wearing an occlusion plate. TMD (Tempromandibularjoint disorders) is a general term for a group of clinical disorders that involve the masticatory muscles or TMJ with some common symptoms (such as popping, pain, and mouth opening restriction), including pterygoid extrinsic muscle hyperactivity or spasm, masticatory muscle group spasm, anterior displacement of joint disc, arthritic disease and osteoarthrosis. All TMJ disorders will be clinically characterized by three major features: abnormal jaw movements, joint popping murmurs, and pain. The pain is mostly in or around the joint area of the temporomandibular joint, which is in front of the ear, and tends to increase when the patient opens his or her mouth or bites. “Some patients also have non-specific symptoms such as tinnitus, headache, abnormal sensation, dizziness, and are accompanied by pain in various muscles and sometimes have difficulty swallowing food.” Injection therapy: intra-articular cavity injection of lubricating medication Treatment of TMJ disorder syndrome is currently available as conservative treatment or surgical treatment. In general, conservative treatment is mainly adopted, i.e., treatment through manual repositioning and intra-articular injection of lubricating drugs such as sodium hyaluronate gel, etc. If necessary, temporomandibular joint occlusal plates can be worn to eliminate temporomandibular abnormalities, relieve muscle tension, stabilize and improve the position of the jaw, and reduce the compression of the condyle on the joint disc. Symptoms usually disappear completely with about two months of treatment. “Intra-articular injection of hyaluronic acid or gibberellic acid into the patient’s joint cavity not only restores the viscoelasticity and physiological effects of the patient’s synovial fluid and improves the mobility of the patient’s joints, but also effectively relieves pain in the patient’s joint area.” In addition, in the case of TMJ, joint cavity lavage must be performed and then injected with sodium hyaluronate gel or giblet sugar, along with oral anti-inflammatory medication for anti-inflammatory treatment. If the symptoms are still not relieved, surgical treatment is required. Surgical treatment includes arthroscopic surgery and open surgery. Currently, temporomandibular arthroscopy is usually done. This is a minimally invasive surgery, which has the characteristics of small incision, less surgical reaction, and can avoid facial nerve damage compared with traditional open surgery, and has better surgical results. Hyaluronate (HA) is one of the main components of joint fluid, and is a polymeric homopolysaccharide with a content of 1.45-3.12 g/L in synovial fluid, with an average of 2.3 g/L. Its physiological role in the joint is mainly lubrication, which not only reduces resistance to joint movement, but also protects joint cartilage and synovial membrane; secondly, it is a molecular sieve, which provides nutrients to cartilage and other tissues, and also serves as a nutrient for the joint. and other tissues to provide nutrients, but also become a natural barrier to bacteria, toxins and immune complexes; at the same time HA has a regulatory role in cell development, can enhance the dynamics of fibroblasts, increase cell surface foaming and wrinkling, but also inhibit the biosynthesis of cartilage proteoglycans in chondrocytes. When osteoarthrosis occurs in the temporomandibular joint, the concentration of HA in the synovial fluid is significantly reduced, resulting in the failure of the synovial fluid to perform its normal physiological functions. The function of sodium hyaluronate gel has been clinically proven that HA can protect the cartilage or enable the damaged cartilage to be repaired, as well as improve the pain, swelling and fluid accumulation in the joint area of patients. Chitosan is a new biomaterial for the prevention of tissue adhesions, with good biological properties, non-toxic, non-irritating, non-antigenic, histocompatible, and can be degraded and absorbed in the body. Some studies have shown that chitosan also has the effects of protecting joint cartilage, inhibiting fibroblast growth and hemostasis. The slow degradation and absorption of chitosan in the joint cavity and the long maintenance of the supra-articular cavity dilatation effect may be one of the reasons for the significant therapeutic effect.