Tony Vargas
Legend
I think the philosophy of 5e is that the DM should trust his gut, and that the system treats wrenches as lubricant.I'd probably give the target a saving throw (in the round after a successful grapple check, assuming the target doesn't escape) to avoid the broken bone. I wonder if that sort of thing would throw a wrench into the system - if you should go through HP like [MENTION=907]Staffan[/MENTION] suggests. My gut feeling is that it would still work okay.