I had knee bone on bone rubbing and taking 1 capsule mornings of chicken sternal/sternum collagen type 2 cured the bone on bone over several months. Improvement occurred within days. I will always take it. It didn't heal my non-painful shoulder.
I also take 1 capsule evenings of the calf bone concentrate "calcium hydroxyapatite" because it feeds the bones and teeth and has type 1 collagen which feeds the ligaments and tendons. I will always take it, although I still have a small amount of bending knee pain but it's no worse.
I also think I would have sensitive teeth if I didn't take calcium hydroxyapatite.
Some joints never heal with supplements, but I think the skeletal system still needs feeding and maintenance with these two supplements.