Yea, I just don't have an ACL in my left knee. Torn it several times and elected not to have surgery again b/c it just doesn't seem to be working. So, I can't do anything that requires planting/cutting, ie, stability of the knee. All of the squats, deadlifts, box jumps, etc., while tough on the knee, don't really require an ACL. B/C you are relatively stable while doing a lot of those items.
Talking to the guy who runs it (who has a degree and extensive background in physical therapy) indicated that I might have some difficulty doing some of the real heavy power lifts where you have to get real low (like sumo squats, etc). However, I should be able to do a large portion of the exercises, unrestricted.
Did the first fundamentals class today and didn't have any issues. Banged out 500M on the row machine in 1:26 seconds.