I read this book several years ago when I believe it was newer. It was the first in a planned series with an elite race of human like creatures that keep the rest of the population in servitude - slum conditions, etc. One of the elite takes in a girl as his slave but it turns out she can actually heal him from being wounded. His family is in conflict with the other elite families and she helps him. I think that "Bone" may have been in the title but I'm not 100% sure of that. It was possibly categorized as a young adult series.