If you are experiencing swelling of the synovial fluid in your knee, it is important to rest and avoid putting pressure on the joint. Applying ice to the affected area for 20 minutes, three times a day, can help reduce swelling. Elevating your leg at night can also aid in reducing swelling. It may be helpful to avoid placing a pillow under your knee while elevating your leg, as this can impede circulation. If you are in pain, you may consider taking over-the-counter anti-inflammatory medication after consulting with a healthcare professional to ensure it is safe for you to do so.