I Need A Knee Replacement,and My Question Is Im In

I need a knee replacement,and my question is Im in severe pain at times and sometimes its tolerable,but when its really bad,my knee down to my toes swell real bad.Is this normal.I first went to my cardiologist and we had my legs checked for blockages and thats all ok.I will admit that when the swelling is real bad I have been standing or trying to walk for a time. Thank you