Latest medical research (I don't know if it's definitive) suggests that glucosamine/chondroitin supplements don't do much, if any, good. I looked for a reference to this study (came out some time this year) but didn't find it.

I unfortunately took the stuff for several months before reading the fine print on the label that it's derived from shellfish. I of course did read the fine print after I broke out in a horrible rash. Whether it's from shellfish itself or from my old allergy to iodine (from using it to disinfect water back in the 1980's), I don't know, but I tossed the rest of the glucosamine bottle and have avoided it since. Anything from the ocean contains iodine, and I should have known better! So should the physician who suggested I take it.

Anecdotally, there was no change to my joints either from taking the stuff or discontinuing it--for whatever that's worth. All I can say is that if you have an iodine or shellfish allergy, avoid it!

Relatively gentle exercise seems to be the best therapy for my arthritic joints. Swimming, walking and strength training with small weights seem to work the best. Keeping up motion and keeping the muscles strong around the joints has worked fine to date.

Have you tried physical therapy for your knees? Do you use trekking poles when you walk or hike?