... i know its possible to make any random joint break at any given moment in a replay by editing the .rpl file... im sure you could edit one to do fractures, but as for LUA scripts... idk:P i havent even looked at how to make these lately :P
I don't see why you would want to fracture yourself... it's like relaxing but you can't change the state of the joint from relax and it deals damage to you :P