A friend of ours advocates bone soup as a beginning to actually repair cartilage. I don't claim to know the science behind this claim. There is bone soup for flavour, there is bone soup for health. The one for health contains as much cartilage containing bits as possible. And yes, this includes knuckles, spines and marrow.
http://www.bonappetit.com/test-kitchen/common-mistakes/article/common-mistakes-bone-broth