Hi there, well I think your best option would be putting in base milage. I wouldn't do too much at once as the constent repititive motion may irritate your knee. ( granted I do not know what kind of surgery you had) I Think if you tried to train for speed you may push too hard and inure your knee. If I may ask, What kind of surgery did you have? Do you have scar tissue? Do have limitations in your range of motion at your knee?