Synovitis fluid in the knee is mainly treated as follows: 1. Conservative treatment: Braking, pressure bandaging, baking, heat application and even iontophoresis are used to help absorption, while activities should be reduced, especially weight bearing on the affected knee. Oral non-steroidal pain medications can also be taken to relieve symptoms and provide some anti-inflammatory effect. 2. Puncture examination: If the above does not provide relief, internal knee puncture can be performed to determine the nature of synovitis by extracting the fluid after puncture and doing the corresponding pathological tests. If the inflammation is bacterial, i.e., purulent, then the bacteria will be targeted. If the inflammation is aseptic, continue to apply pressure bandages to prevent exudation. Strict aseptic operation must be performed throughout the process to ensure that no infection occurs after the puncture. 3. Detailed examination: If the symptoms still cannot be relieved, it is necessary to consider going to the hospital for detailed examination, such as magnetic resonance examination, to observe the cause of the effusion, and also to induce the effusion from the knee joint before systemic treatment.