Waterlogged knee should be treated according to the cause. Common causes include too much exercise, gouty arthritis, infectious arthritis, etc. The treatments taken include puncture treatment, medication, and so on. 1. Excessive exercise: long-term repetitive movements of the knee joint can cause acute attacks of knee arthritis, synovial congestion, edema, oozing, pain, accompanied by fluid accumulation. Knee joint puncture is feasible to extract fluid and blood, inject sodium hyaluronate to protect articular cartilage. 2. Gouty arthritis: during acute attack, there will be redness and swelling of knee joint, severe pain, limitation of joint movement and fluid accumulation. In addition to puncture to extract fluid, colchicine tablets and diclofenac sodium extended-release tablets should be taken orally. 3. Infectious arthritis: caused by bacterial invasion of tissues, occurring after systemic infection, manifested as knee pain, redness, swelling, fever, fluid retention. Bacterial culture and drug sensitivity test can be carried out, effective antibiotics can be used to control the infection, and surgical drainage can be carried out to remove abscess and necrotic synovial membrane completely in serious cases. There may be other causes of knee effusion, and it is recommended to go to the hospital in time. The above medication should be administered under the supervision of a doctor.