Osteoarthritis isn't the truly 'inflammatory' type - rheumatoid arthritis is, and while you can have a 'flare' of OA, the majority of the trouble with it is that it's mechanical, and not a question of heat, redness and swelling as you'd get with RA, and therefore taking something prescribed for 'inflammation' reduction won't help and could create new problems. OA, unfortunately, isn't going to go away, just be worse at times - if there was a magic answer millions of people would already have found it. I looked at that website, and what they're selling (Bromelain, Licorice, etc. etc.) have been around for years and years (and could well irritate your stomach) and have been tried for almost every ailment you can think of. They are no more likely to help your knee than pea soup or a chicken sandwich would be and will cost you a lot more. I personally would ask my MD for appropriate exercises, and find out how long the list is for knee replacement, as that's often where the problem ends up (and where within a couple of weeks, you feel 100% better once the surg. is overwith).

Cayenne is also good for arthritis... I just rummaged around in Michael Moore's site... Mr. Moore being a WELL respected herbalist.
I found this article, for an easier read for a layman. They use Capsicum frutescens, I am not sure why, except it's a british article... I think people in the U.S. use capsicum anuum.

Here is a link that might be useful: arthritis and cayenne

Osteoarthritis has a number of possible causes(mine is from a motorcycle accident;I know a person with AIDS who has it from bacterial sepsis) I take Du huo, 3 capsules, three time a day(90 pills for 6.00 at the Vietnamese market in Denver). This is off and on for a few months or a few weeks depending on the season and how much I hurt. I like it better than glucosamine, which needs chondroitin to work well and is too expensive for me.