Fluid density in the joint cavity is considered to be joint effusion, which is related to trauma and intra-articular inflammation, etc. The main treatments include braking and resting, medication and closure treatment. 1. Braking and resting: If there is a small amount of joint fluid in the joint cavity and the clinical symptoms are not obvious, it is recommended to take less walking and weight-bearing activities, and take more rest. If the joint fluid is caused by trauma, ice packs can be applied in the early period within 72 hours, and hot packs can be applied in the recovery period, and the fluid can gradually be absorbed by itself. 2. Drug therapy: you can choose antipyretic and analgesic drugs such as ibuprofen, aspirin, etc., or short-term oral glucocorticoid drugs such as dexamethasone, methylprednisolone, etc. to ease the pain, and if it is an infectious arthritis, you should choose antibiotics such as cephalexin, oxfloxacin and so on. 3. Closure therapy: for patients with particularly large amounts of fluid in the joints, joint puncture and fluid extraction can also be carried out, but also through the injection of drugs into the joint cavity, such as trimethoprim, prednisolone, sodium vitrate, etc. for closure therapy to improve the symptoms of joint pain. Fluid density shadow can be seen in the joint cavity should communicate with the doctor in time, cooperate with the doctor to carry out standardized treatment, and mainly rest. All of the above medications should be used under the guidance of a doctor, avoid self-medication.