How long are you on crutches after you sprain your knee?

up to a few weeks..: Depending on the severity of your injury and the level of need to walk/use your leg etc..Crutches are only need for a few days to couple of weeks in most cases. You tend to heal faster when young and in good health and longer and longer with age and concomitant illnesses. Often after a few days, you can hop around w/o cructhes. Consult doc. Good luck.