Another data point. I had ACL replacement surgery about 10 years ago. Patella tendon graft. It took about 1 year to fully recover the knee function and a few more before I could kneel comfortably. I think if I had to do it again, I'd very seriously consider an allograft (cadaver tendon) because it really speeds the recovery. Heed the other advice and hit the PT hard. I think that within the year, my knee with the replaced ACL was more stable than my other one. I don't worry about it at all any more, ski hard, climb and hike, and have never used a brace (my doc said that they don't help that much and you should just work on strengthening your quads and hamstrings -- YMMV). Good luck.