The synovial membrane of the knee is the most extensive and complex of the human joints and forms the largest synovial cavity and forms fissures to accommodate the various movements of the knee joint. Because the knee joint is heavily loaded and subject to many movements, it is most likely to be damaged, so synovitis of the knee is most common in clinical practice. The synovial membrane is mainly located around the joint. It communicates with the joint cavity and secretes lubricating fluid to lubricate the joint. The synovial membrane is stimulated by various pathogenic factors (such as osteophytes, arthritis, tuberculosis, rheumatism, etc.) or directly stimulated by traumatic trauma, bone injury, intra-articular injury, peripheral soft tissue injury, surgery, etc. The synovial membrane responds to the inflammatory stimulus by secreting exudate. Strictly speaking, as long as there is exudate accumulation in the joint, it proves the existence of synovial inflammation, whose main manifestations are joint congestion and swelling, pain, increased exudate, joint effusion, difficulty in moving and squatting, and functional limitation. Synovitis etiology When the knee joint is directly hit by violence, long-term weight-bearing chronic strain, indirect knee sprains, injuries during surgery, strenuous sports activities or super-intensive 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 cell activity to produce a large amount of fluid, which contains plasma, leukocytes, and phagocytes. It contains plasma, leukocytes, phagocytes and so on. Normal synovial fluid is alkaline fluid, but due to the increase of exudation after injury, the synovial fluid becomes acidic due to the accumulation of acidic products in the joint, which leads to the precipitation of fibrin. If the accumulated fluid is not cleared in time, the synovial membrane will have a long-term inflammatory stimulus response, which will lead to the gradual thickening of the synovial membrane and fibrous mechanization, causing adhesions and affecting the normal activities of the joint. The fluid extracted by arthrocentesis is mostly yellow and clear, or pink with blood and negative 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. How is synovitis treated? The first step is to avoid sports that cause trauma or strain, and to reduce weight bearing and flexion/extension activities in the knee. Exercising the quadriceps is an important and effective therapeutic measure. Straight leg elevation promotes blood circulation and facilitates absorption of joint effusion. Mild synovitis generally does not require bed rest and can be walked for short distances. If the amount of effusion is high, proper rest should be taken, the affected limb should be elevated, and functional knee exercises should be done in bed. Medication: Western medicine generally takes fluid extraction, local injections, compression bandages, and antibiotics to control the condition. If the inflammation is not completely eliminated, the fluid will be pumped more and more, and the condition will gradually become chronic, with synovial hypertrophy, fibrous calcification, joint adhesions, and limited function. In recent years, our center has used amber cream for external application, assisted by nine needles, taking Yi kidney soft capsule treatment, and achieved 99% complete treatment effect, serious patients can eliminate edema within 10 days, 1-2 treatment course completely cured.