If a fighter throws a punch and breaks his own arm, what is the ruling?

[Spicoli]

If you break your own arm, it's your fault and it results in a ko. If your opponent throws, grabs, or does something illegally to cause you to break your arm, depending on what happens, it may result in a DQ win or a No-Contest at best.

See Tyson/Norris for a no-contest that ended up with Norris turning his knee and was unable to continue and See Hopkins/Dawson for another- Hopkins fell/thrown on his shoulder and unable to continue. The fights were ruled no-contests.

The crazy thing is the exact same thing happened to Norris earlier in career and was ruled a tko and wasn't result of a punch like Tyson. I don't think there is a definitive rule and seems very much random. I mean the record book says Pat Lawlor knocked out Roberto Duran but it was a combination of a shoulder separation and a hook right on it to help it out . I remember Takumbo Olajide being dropped by Mendoza and twisting his ankle resulting in tko, same as Tyson from a punch. Seems like a real shat way to lose yeh.