In my game we allow PCs and major NPCs the right to *always* make
final action rolls. However the target number to beat is the skill
the opponent used to defeat you + the APs you are below zero. If you
are not defeated you go back to 1AP not the usual. Your PC can now
lurch around the battlefield with two broken arms to his hearts
content.
I would agree that a major injury would always defeat you except
I've seen a no-holds-barred fighter continue to a draw with a broken
wrist.