"The results for the use of glucosamine for osteoarthritis are mixed and the size of the effect is modest. There’s some evidence that more recent trials and those using higher-quality methods are less likely to show a benefit"
// Chondroitin sulfate and glucosamine are popular supplements used to treat the pain and loss of function associated with osteoarthritis (OA). However, most studies assessing their effectiveness show modest to no improvement compared with placebo in either pain relief or joint damage.//
so it seems no but there is no harm in tryhing
so long as you dont spend too much
Don't bother. I took it for years ( it felt like years ) and made no difference at all. Zero. Most important is to keep your weight down. That did make a difference when I lost 15 kilos.
I found that the only thing that helps with arthritis pain is reducing inflammation- which I have chronically (very high ESR and CRP every blood test), and the best way I've found to do that is to fast. By giving your system a rest, it can heal you. And you also lose weight which helps everything. By eating food that suits you (ie- for many, avoiding gluten and dairy helps) that will reduce inflammation in your system. It won't repair your knee but it might help with the pain.