I have had surgery on BOTH knees for ACL replacement, both by the (literally) world-famous Dr. Andrews of Birmingham AL.
I was cleared for any excercise I wanted to do after 6 months the first time, when I was 28 and in much better shape.
For the second one, which was just last year, I was cleared for aggressive rehab after 6 months but not full activity till a year later, and I was 43 for that one (Jan 2010).
My knee that was operated on last year is fully recovered and has been for at least a year. I don't do everything I did though (like soccer) because I haven't really rehabbed it the way I should. I got it functional and got lazy. At my age, that may not be a bad thing.
There is a guy in his 20s that had the same surgery shortly before me. He never bothered to use crutches at all (it's optional) and was back to playing soccer just 5 months later, albeit with a brace and not quite full speed. But a year later, he was probably full speed or at least 99% back. There may have been just a bit of hesitation, but it was mental.
Justin is barely 20 if that, and will do a much, much more intensive rehab than me or my much younger friend. I expect him to practice in the spring and be almost fully recovered in the fall. He may take a game or two to shake the rust off, but he will be fine IMO.
My concern for him would be from looking at his physique. He has really long skinny legs, which are ideal for injuring one's ACL. IMVUO (In My Very Unprofessional Opinion) he should have a regimine (sp?) of strengthening BOTH knees as long as he plays football. specifically he should really strenthen his quads, which is what I am supposed to have been doing the last year or so.
