Originally Posted by ollinger
^^ as cartilage is non-vascular, healing is unlikely and generally not seen; your friend's MRI is more likely to have been misread. This nonvascular nature of cartilage makes it nearly impossible for growth or repair building blocks to get to it, except for miniscule amounts in joint fluid, but it's not clear even all the ingredients for growth are found there.
OK, I can understand the MRI being misread.
So why do you think there are reports of pain reduction with joint supplementation? One theory of heard is that somehow the supplementation is bring more fluid into the joint and thereby reducing pain, not that it is actually causing any repair to the damaged cartilage. I know that some doctors are injecting HA into knee joints but I don't know how well such treatments have been studied compared to a placebo or just injecting water into the joint.