Synovitis of the knee is the most extensive and complex of the human joints and forms the largest synovial cavity and forms folds to accommodate the various movements of the knee joint. Synovitis of the knee is the most common in clinical practice because the knee joint is heavily loaded, has many movements, and is most susceptible to injury. The synovial membrane is mainly located around the joint. It communicates with the joint cavity and secretes lubricating fluid to lubricate the joint. When stimulated by various pathological factors (such as osteophytes, arthritis, tuberculosis, rheumatism, etc. and traumatic trauma, bone injury, intra-articular injury, peripheral soft tissue injury, surgery, etc.) or directly stimulated by synovial injury, the synovial membrane responds to the inflammatory stimulus by secreting exudate. Strictly speaking, as long as there is exudate 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 limited function. Western medicine treatment is mainly to extract the fluid, hang anti-inflammatory bottles and use antibiotics. However, it is not possible to completely eliminate the other causes of synovitis, so the condition can recur. Synovitis is a non-infectious inflammatory disease that occurs when the synovial membrane is damaged or ruptured as a result of acute trauma or chronic strain to the knee joint, resulting in the accumulation of blood or fluid in the knee joint cavity. It can be divided into acute traumatic synovitis and chronic injury synovitis. Acute traumatic synovitis occurs in young people who love sports; chronic injury synovitis occurs in middle-aged and elderly people, obese people or people who overuse the knee joint for weight-bearing. Etiology: 1. Acute knee synovitis mostly occurs due to blows, twisting, excessive movement and 1-2 hours after surgery with swelling, pain, difficulty moving, walking limp, high local skin temperature, swollen and tense skin, and joint puncture with hemorrhagic fluid. This disease is often a comorbidity of other knee injuries and must be differentiated from fractures, dislocations, ligament and meniscus injuries. 2. Chronic knee synovitis is usually caused by acute traumatic synovitis failure, or by other chronic strains in the elderly that lead to inflammatory exudation of the synovium and produce joint effusion. It is mostly seen in middle-aged and elderly people with a history of strain or joint pain. Patients feel heavy in both legs, swollen joints, difficulty squatting, or pain going up and down stairs, which is aggravated after exertion and cold, and alleviated after rest and when warm. If the disease is prolonged, the quadriceps muscle atrophy, joint instability, and restricted movement are seen. pale yellow, clear fluid can be extracted by joint puncture. x-ray shows no obvious abnormality in the bone and joint structure of the knee joint or bone formation, and joint swelling and unfavorable movement are seen. Symptoms: 1. If the injury is acute, knee hematoma. Joint hematoma usually occurs immediately after the injury or within 1 – 2 hours afterwards. 2, chronic strain or injury knee synovitis patients complain mostly of heavy discomfort in both legs, difficulty in knee extension and flexion, but no significant impairment in any of the passive movements, pain is not intense, local redness is not hot, and functional examination of the knee joint generally has no obvious positive signs. 3. 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-intensive training, incorrect habitual movements, degeneration of the joint itself, knee joint reversion, and even improper shoe wear can cause traumatic synovial damage, synovial congestion, swelling, and synovial cell activation to produce large amounts of fluid, etc. Examination: Knee arthroscopy, X-ray, etc. Treatment: Knee arthroscopy Surgery, etc. Minimally invasive surgical treatment, fast recovery, low cost and less trauma. The disadvantage of previous surgery to remove synovial tissue is that it is very traumatic and the lesions in the synovial folds in the joint are difficult to be completely removed, which prevents early functional exercise after surgery and leads to adhesions in the knee joint. This type of surgery has a small incision (5 mm) and is less traumatic; it can be used for functional exercise on the second day after surgery and generally does not leave joint deformity; it can treat almost all synovial membrane in the joint without damaging normal tissues on the basis of accurate removal of synovial membrane, and the removal of lesions is more thorough.