After a knee replacement you might experience mild to general pain and swelling for as long as 3 to 6 months after knee replacement surgery. The overall healing process can take up 6 to 12 months. According to the American Academy of Orthopaedic Surgeons, many people experience moderate to severe swelling in the first few days or weeks after surgery and mild to moderate swelling for 3 to 6 months after surgery. You can reduce swelling by doing the postoperative exercises provided by your physiotherapist. Elevating your leg on a pillow in bed for several hours each afternoon and using compression stockings will also help.