Here's my two cents.....
I have had knee problems for years.
I am a very young and active 63, still working, and learning to metal detect. Over the years I have hunted, fished, hiked, used a walk-behind Gravely (For those of you who know what they are, you know that they can be a man killer to work with.) and done some consulting forestry and walked up a million flights of steps with my make-a-living job. My knees have simply taken a beating.
I have taken various combinations of glucosamine, chondroitin, MSM, hyaluronic acid, hocus-pocus weed, etc. (mostly Osteo bi-Flex) for years. As long as I exercised some and took the bi-flex (or similar stuff) I got along just great, even after I found out a few years ago that the meniscus in my left knee is shot!
A few months ago I had pain in my right knee so bad that I knew I was a candidate for knee replacement. Could barely walk with terrible pain without taking something. Of course, when I started favoring the right knee, the left one went south too. Went to the dr. and he said it was irritation, really bad irritation caused by a bump or something. Time would heal, and it did! Two weeks after going to the dr. I was almost over it. This was after suffering for a few months. (I believe we sometimes cure ourselves by just going to the dr.)Crazy!
After all of this I am still taking Osteo bi-Flex, with 5-loxin Advanced Triple-strength none-the-less. It's not cheap. Got a bottle the other day. My wife had a coupon, and I found it on sale. Cost me ten bucks , a third of the normal price. I still have a bit of swelling at times but no pain. Over the years I believe it to be the glucosamine and chondroitin that has helped most. Of late, I think some of the more exotic additives have helped too.
My knee doc, whom I respect greatly, told me the jury was still out on the glucosamine thing. I said "not for me!"
For me it's Osteo Bi-Flex and an occasional ibuprofin or two.