I've seen where at different times people want to know if they have a hairline fracture. I am wondering what is supposed to be the difference between a hairline fracture and a fracture, aren't they really the same thing? Or is there such a thing as a hairline fracture? I couldn't find it in any of my medical books. And if there was such a thing, would it be painful or not? I know bones don't have feeling sensors to them so they don't feel pain, so why if someone is in pain would they call it a hairline fracture?