Cartilage heals poorly and in many instances does not heal or recover at all after a severe injury Why not?

Cartliage take over a year to heal. When I got mine done it took about a year and a half to heal. This is because your cartilage doesn't produce it's own blood. So when you get it pierced it has to wait to get blood and oxygen from the rest of the body. So this of course is why it takes such a long time to heal