Many outpatients are nervous when they hear “you have synovitis” and think they have a serious disease. As the name implies, synovitis is an inflammation of the synovial membrane of the joint, so to understand what synovitis is, we need to first understand the anatomy of the joint. We all know that a joint is a complex structure made up of bone, cartilage, synovium, muscles, ligaments, and tendons, with narrow internal spaces that we call joint cavities. The synovial membrane is the lining of the joint cavity, just like the wallpaper in a room, which not only maintains the integrity of the joint and cushions the joint from all directions of impact, but also continuously secretes synovial fluid, which exists on the surface of the bone and cartilage and plays an important role in lubricating the joint and reducing friction during movement. Among the many joints in the human body, the knee joint has the most complex structure, the largest intra-articular space, and the most abundant synovial tissue, and because the knee joint is almost the most frequently used joint in daily activities, the synovial membrane of the knee joint has the greatest chance of being damaged, which explains why synovitis is most often seen in the knee joint. This explains why synovitis is most often seen in the knee joint. When the body over-exercises or when the knee joint is sprained or injured, the synovial tissue becomes congested and edematous, and a large amount of fluid is secreted, causing a build-up of joint fluid and increasing pressure in the joint cavity. Due to the inflammatory factors in the joint fluid, the knee joint is often painful and swollen, and the patient is unable to bend or take steps. These are the signs of the acute phase of synovitis. In the eyes of experienced clinicians, synovitis is both common and curable. The secret to treating synovitis in our department is six words – rest, anti-inflammation, and decongestion. Damage to the synovial membrane is the starting point of the disease, so once synovitis is diagnosed, the first thing to do is to give the joint some rest to prevent the synovial membrane from being bruised again and the inflammation from worsening; synovial inflammation is the course of the disease, so anti-inflammatory drugs should be used as early as possible and taken regularly to stop the synovial membrane from continuing to secrete inflammatory fluid to reduce the symptoms of pain and swelling. Joint swelling is a manifestation of the disease, so drugs that promote the absorption of joint fluid should be used, along with physical therapy to accelerate blood circulation around the joints and reduce swelling as early as possible. Early, standardized and reasonable drug treatment is the key to the treatment of synovitis. The natural course of synovitis is usually about 1-2 months. After regular treatment, the symptoms will be gradually relieved and the effusion will slowly disappear. Patients need to be patient, take their medication regularly and protect their joints in their daily life. If treatment is delayed, medication is inappropriate, or rest is inadequate, synovitis may persist for months or even longer, and long-term synovial inflammation can accelerate the aging of synovium and cartilage and increase the risk of infection within the joint cavity. The Yellow Emperor’s Classic of Internal Medicine says: “The doctor does not treat the disease to cure the disease, and does not treat the chaos to cure the chaos. We hope that you will protect your joints in your normal activities and go to a major hospital for regular treatment as soon as possible once joint problems occur.