Someone who knows that I do agility passed along this post to me and I just had to respond. YES, there is agility after major knee problems. Some of it is easier, some of it is harder.
My story doesn't have an ending yet because, like you, I'm in the midst of knee issues. I did however, after my first surgery to repair cartilage (microfracture) run my fast sheltie for about 3 years. I've now had a second microfracture surgery done (different spot) and have not been able to run since.
However, I belong to a Yahoo list called "agility knees" that has umpteen people who have had knee replacements and are out there running! Granted, distance work does become a necessity and that last minute front cross isn't going to work well, but one gal (in her late 60's or early 70's) just competed with her two fast Borders in the AKC National Agility Championships.....There are videos of her. She's got great distance handling, but admits there are courses out there that she just can't qualify on.
If you are a die hard agility fan, I suggest joining that group and asking questions there. There's a lot of talk about "running" vs protecting the implant, etc. Some docs are adamantly opposed, some see it no different than gentle doubles tennis or ballroom dancing, both activities supposedly ok for certain knees.
Run clean, run fast -