After an ACL reconstruction, the rehabilitation is staged in various levels. First we really want to control swelling and get range of motion of the knee back. After that you will begin a gradually progressive strengthening program under the guidance of a physical therapist. Over time you'll be released to a home program of exercise. This period may surprise people in that it's quite long, and it takes about six to nine months to get back to aggressive activity and some of the sports you may have been playing before your ACL injury.