Is there any chance of becoming septic with a punch biopsy, I had knee replacements done?

Highly unlikely. The possibility of sepsis is highly unlikely with a punch biopsy. It is a relatively shallow removal of about 4 mm of tissue at the most, and no vessels bigger than capillaries are likely to be involved. People get this and go home the same day, so if it was deeper, and things like sepsis were involved, hospital stay and more intensive monitiring would be done. At most, a return visit is done.