Pulled up today to move traps because sign disappeared. Found this little girl. Still moved traps. Back leg catch on blind set at gate opening between pastures. First animal I've ever seen with broken leg in trap. Don't know how she did it. She has a den and pups nearby somewhere so maybe she just tried harder than most.
My guess would be that somehow the swivels got locked up on your trap. If you are using a 2 coil trap, if you don't clip the extra spring pins, sometimes the chain can get hooked on there and keep the trap from swiveling properly. I had it happen on a grey fox one time.