Synovitis, a multifaceted disease, develops mainly in the knee joint. It can cause temporary or long-term partial loss of labor force, which is harmful to both the patient and society. Synovitis is classified as infectious synovitis, osteoarthritic synovitis, tuberculous synovitis, and traumatic synovitis, depending on the primary cause. At present, although there are many effective treatments, many patients are still not cured. Especially some young and middle-aged patients have to bear many social and family responsibilities, while suffering from pain for a long time. This is undoubtedly a problem that urgently needs to be solved by our medical professionals. The knee is the joint with the most synovial membranes, the largest articular surface and the most complex structure. Because the synovial membrane of the knee is extensive and located in the superficial part of the limb, it has more chances to suffer from injury and infection. Such as meniscal injury, synovial injury, cruciate or collateral ligament injury, intra-articular injury and dislocation, knee osteoarthritis secondary to chronic synovitis of the knee and joint free bodies. Another cause is infection, of which synovial tuberculosis is common. Generally speaking, the synovial membrane is rich in blood vessels, has good blood circulation and is resistant to bacteria, but in the case of infection with tuberculosis bacteria, the disease progresses more slowly and its symptoms manifest sometimes, this is one of the chronic synovitis of the knee joint. Synovitis is an aseptic inflammation caused by poor microcirculation, the main symptom is fluid accumulation, patients often feel restricted movement, pain in the joints when going up and down stairs, afraid to make efforts, afraid to squat, stiffness in the joints when standing up for a long time, hollow feet, most serious cases of joint swelling, fluid accumulation, deformation and even lower limb paralysis. The synovial membrane is a layer of membranous tissue that surrounds the joints. It is not only a layer of tissue that protects the joints, but also produces joint fluid, which provides “lubricating fluid” for joint activities. The production and absorption of joint fluid is a “dynamic equilibrium”. When the reabsorption of joint fluid is impaired, the dynamic equilibrium between the production and absorption of joint fluid is broken, and the production of joint fluid is greater than the reabsorption, then “joint effusion” occurs. The main symptoms of synovitis are as follows: 1. Mild synovitis: joint pain is the main cause, joint swelling is not obvious or accompanied by mild swelling, walking creaking sound, joint pain or discomfort when walking up and down stairs or exerting force. 2, moderate synovitis: joint swelling, pain is not obvious, squatting or bending with discomfort, individual patients appear muscle atrophy, swelling after excessive exercise. The symptoms are lighter in the morning and worsen in the evening. 3, severe synovitis: joint swelling, pain is more obvious, and accompanied by effusion, bone spurs, free bone. 4, osteophytes: joint pain, swelling is obvious, going up and down stairs is more powerful, stiffness and inflexibility, creaking and popping sound when moving. 5. Patellar chondromalacia: the joints are sore and weak when walking, the legs are weak when running and cannot be extended and flexed. The pain increases when going downstairs and disappears when resting. 6, meniscal damage: the leg is easy to don’t have strength when walking. Occasionally, the leg suddenly can not walk, feel like there is something to stop the leg, you have to rest a little to return to normal. In general, people who love sports or special occupations have a higher chance of injury. After a long period of time, the disease will be accompanied by atrophy and deformation of the calf muscles. There is also a special group of people, synovitis symptoms appear in the ankle joint, hip joint (hip bone); symptoms are different from other joints; but the pathology is basically the same.