Yeah, they sewed them back on. He spent a couple of weeks with a huge bandaged fist. Like any child he was hugely resilient but every now and then he'd spot his bandages (usually when they got in the way of climbing or some other mischief) and say "ow.... poor me" and then kiss his bandaged hand.
As usual it is the adults that wear the lifelong scars.... I doubt my nephew even remembers it but my sis felt awful and now, years later my sisters and I won't use oil fin heaters at all around small children.