That's because it is unclear.

Glucosamine and Chondroitin for Arthritis: Benefit is Unlikely

I won't tell you it doesn't work for you, because the studies are admittedly inconclusive, and I know many people who swear by the stuff. OTOH, I've been trying it on and off for years, for months to years at a time, and I can't say it's made an iota of difference. And I know others who've had the same experience. Bottom line, the stuff is expensive, and some of us have to make choices.

Maybe the article, and/or its references, will provide the information you're seeking.

Best wishes,

Doc