A few days. Five to a week, to be absolutely certain.

It will be sore for a while even after it's healed, so at least try to be careful with it, won't you? [ He says this with the tone of someone who doesn't exactly expect to be cooperated with, because he knows Kano well enough that he'll probably be getting back into trouble in no time at all. ]

Fixing these kinds of injuries is what I'm here for, but I'd rather not have to keep treating them, if it's at all possible. [ Even with magic, it's still a painful and distressing thing to break bones and sustain large injuries, after all. ]