Hạn chế hoạt động đầu gối. Chườm đá lên đầu gối. Tránh hơi nóng trong vòng 48 giờ đầu tiên. Sử dụng băng nén. Mát xa đầu gối nhẹ nhàng. Giảm cơn đau bằng loại thuốc giảm đau không cần theo toa.

I'm interested in that, but I only have a few mins. Can you give me at most the first 500 characters of a detailed explanation in English about that?
Stay off your leg and do as little walking as possible.  Keep the knee elevated above your heart while lying down. Prop the knee and foot on pillows or on the arm of the couch. Use crutches if it hurts to straighten the leg or to put weight on it. If you need crutches for more than a few days, you should see a medical professional because it may be something serious enough to require more than home care. Apply ice directly on the swollen part of your knee for 10-20 minutes. Do this 3 times a day