I. Knee synovitis Knee synovitis is a group of syndromes caused mainly by knee sprains and a variety of intra-articular injuries. 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 more resistant to bacteria, but in the case of infection with tuberculosis bacteria, the disease progresses more slowly and its symptomatic performance is sometimes good and sometimes bad, this is one of the chronic synovitis of the knee joint. Clinical manifestations and diagnosis 1. Chronic strain or injury knee synovitis Acute knee synovitis can become chronic if not treated properly, and is clinically seen in elderly people, those who are wet, or patients with internal knee, external knee or other knee deformities, or those with osteophytes of the knee. Patients complain of heavy discomfort in both legs, difficulty in knee extension and flexion, but there is no obvious obstacle to passive movement, pain is not intense, local redness is not hot, and functional examination of the knee joint generally has no obvious positive signs. The common phenomenon is: in the knee ligament on both sides of the knee eye bulge, full, palpation with the hand, the place is soft, or even cystic feeling, joint fluid if more than 10 ml is positive floating patella test. 2. Acute injury, knee hematoma Joint hematoma usually occurs immediately after the injury or within 1 – 2 hours afterwards, with extensive petechial hematomas on the knee and lower leg. There is tension in the skin or swollen area on palpation and a positive floating risk test. There are often systemic symptoms, such as fever due to stasis and more localized heat. The disease is often a comorbidity of other injuries. Careful clinical examination is needed to prevent missed diagnosis. 3, long-term weight-bearing chronic strain and other When the knee joint is directly hit by violence, long-term weight-bearing chronic strain, indirect knee sprain, injury during surgery, strenuous sports activities or super-intensity training, incorrect habitual movements, degeneration of the joint itself, knee joint reversion, and even improper shoe wear can cause traumatic synovial injury, synovial congestion, swelling, and synovial cells are active to produce a large amount of fluid, which contains plasma, white blood cells, phagocytes and so on. The synovial fluid is mostly yellow, clear, or pink with blood, and negative for bacterial culture. x-ray examination of synovitis bone is not abnormal, or there are degenerative changes, or there are intra-articular free bodies and bone spurs at the edge of the bone joint. Most knee synovitis, which is complicated by the various knee injuries mentioned above, etc., can also develop alone or secondary to knee osteoarthritis, the latter mostly in the elderly. In young adults, there is a history of acute knee trauma, and mild edema, pain, limited motion, and claudication of the knee begin to occur after the injury. Synovial reactive effusion usually appears 6-8 hours after the injury, and the knee joint is obviously swollen, warm and afraid to move. Examination reveals limited knee flexion and extension, difficulty squatting with pain, and there may be limited pressure pain points around the joint with a positive floating patella test. Chronic injury to the synovium, which may not have a clear history of trauma, is characterized by tenderness and limitation of knee movement, persistent swelling, and fear of squatting. The swelling is persistent and prevents squatting. It increases with increased activity and decreases with rest. In patients with prolonged disease, hypertrophy of the knee capsule may be detected. For those who have a lot of fluid in the knee joint or those who have repeated fluid accumulation, joint fluid examination can be done, which can reflect the nature and severity of synovitis. Therefore, arthrocentesis and synovial fluid examination have important reference values for the diagnosis and differential diagnosis of synovitis of the knee. Arthroscopy is an emerging method of examination and surgery in recent years. The application of arthroscopy for synovectomy and joint debridement has the advantages of small incision, less trauma, basically does not affect the functional activities of the joint, fast functional recovery, and can remove the synovial membrane during the procedure for pathological examination to further clarify the real cause of synovitis.