I'm missing about 30ish% of the cartilage from both knee caps and some more from my meniscus. I also work on my feet so they're pretty much always in pain.
What I do now:
When I skate I use a brace on each knee (
http://bungapads.com/bunga-knee-brac...e-support.html) They're getting old and I think I need to upgrade.
Advil for pain. (I've tried glucosamine but it never did much for me.)
Went from 1/2" hollow to 5/8". The shallower hollow allowed for less chance of me catching an edge and something tweaking. For me, if something is going to give it's going to be in my knee.
I'm on the ice 1-2x per week. I try and take it easy as I'm not making a living from playing and I don't want to lose any more cartilage.