The jury is still out on whether or not glucosamine and/or chondroitin are effective in arthritis pain. Most of the studies showing a positive benefit were either funded by companies which manufacture the supplements or did not make clear where their funding came from. Of note, three decent trials which did
not take funding from supplement manufacturers showed no difference between glucosamine and placebo. Chondroitin has even less evidence to support its use.
My take on the situation is that it's either of small benefit or none. The good news is that it seems to be fairly safe, so the only thing you'll likely to harm by trying it is lightening your wallet a bit.
no benefit in placebo controlled trial