In reply to mike123:
It works. At least for me.
I've tested it on myself several times, and every time if I don't take Glucosamine for 1-2 weeks my knees and hips ache badly during and after walks. When I go back on it again, I'm back to normal.
I use Boots own brand which are fairly expensive but good quality, and they usually have a 3 for the price of 2 offer on, making the cost reasonable. I take one capsule in the morning and another before bedtime.