It's not likely that a knife wound is going to break a bone, but if it did it was either so sharp or with so much force behind it that the fracture would likely be the least of the problems. The logical wound is a "boxer break", a fracture of the fifth and sometimes also the fourth metacarpals from punching something with a closed fist. It's the classic ER visit on Ash Wednesday, New Year's Day and November first (the morning after big parties, and some people get punchy when drunk). There'd be one guy with a boxer break and a few beds down there'd be another guy with a broken jaw. Being a bone with relatively weak muscles attached to it, the fifth metacarpal is one of the easier bones to set, and one that often is initially treated with a splint by a doctor on call in rural ER's and then the person sees an orthopedist the next day or so. You basically use traction in line with the normal position of the bone until it looks right, apply a cast or splint and check the final position with an X-Ray. That's a bit oversimplified, but it's a reasonable thing for a nonsurgeon to actually have experience with since a lot of medicine residents will work part time in ER's for extra pay, and in rural areas internists and family practicioners might do ER duty as well.