I once sprained my thumb when a bit of wood in a vice in the DT lab slipped and bent it back.. I told the DT teacher and she said it was fine, got home and it'd swollen up massively, so I had to get it potted up. Her face next day was great.
I still have a lump on the joint though actually, they ultrasounded it and said that a bit of bone had chipped off and was floating about in there - LOVELY.