I delayed knee replacement surgery last summer on the advice of my rheumatologist. I was on 15 mg. prednisone at the time. I was also advised that 5 mg. is ideal, but my orthopedic surgeon was less concerned than my rheumatologist. The reason I was given was the increased risk of infection on higher prednisone; they said my surgery healing would actually be enhanced by the prednisone helping with inflammation. I had the surgery in March when I was on 5 mg. No issues at all -- the new knee is doing well. My rheumatologist also warned of a potential flare after the surgery, which did happen. My sed and c-reactive rates both rose for a couple months after surgery.