A person should elevate a swollen knee, states WebMD. Elevation is the final step in a technique for treating knees called "RICE," which stands for rest, ice, compress and elevate.
UpToDate suggests employing the "ice and elevation" aspect of RICE for 15 to 20 minutes as frequently as every two to four hours, especially after physical activity. The knee should be elevated above the level of the heart. WebMD suggests making an appointment with a doctor if pain in the knee persists after two weeks of the RICE treatment. UpToDate recommends non-prescription pain medication if needed and sessions of gentle, gradual stretching up to four times daily.