Ken,
with your bad knee and my bad back, we could sure make a funny pair to hike in lol. Seriously, there are some tight spots that coupld potentially affect your knee, if you take your time, you should be fine. I am scared when I hike in because if my back goes out, I am in deep trouble as I lose the use of my right arm and right leg. I still do it but go in and out slowly. Its an incredible sight when you get there and are able to enjoy the natural beauty of the area with the waters!
Dont know if that helps or not but I would say its worth a try.
Craig