There are many reasons for the clinical form of knee hydrops, most of which are related to the injury of synovium. Synovial injury leads to increased secretion of synovial cells, increased effusion secretion and joint cavity effusion. The common causes include rheumatoid arthritis, tuberculosis, bacterial infection, etc. In short, there are many reasons for joint cavity effusion and incremental swelling, including acute suppurative arthritis, chronic bursitis, traumatic bursitis, and proliferative arthritis. First of all, you should stay in bed and rest, and plaster brake if necessary. Cooperate with physical therapy and massage, and take anti-inflammatory and analgesic drugs orally. The above health science knowledge is for reference only.