Hey!
That sucks! I know, I've had five knees surgeries: total reconstruction on right, 1977, bucket tear on left in 1986, basic cartilage tear on right 1997, new impact on knee with knee cap smashed into cartilage under it plus broken knee cap left 2002 (car accident), new cartilage tear on left 2010 (ice skating).
OK! Find a competent surgeon. Do the exercises they recommend and don't stop doing them. Don't get into car accidents post surgery. No ice skating. Other than that, it should be fine.
Hugs
Jen