When it comes to bones, it depends on the physical build, in verse context, and what the broken bones are adapted to withstand initially.
Generally, without any other calculations, a standard forceful blow to the head/torso/arms is generally around 10-B to 10-A energy depending on the weight+gender+physical build of the person. This is considering the fact that
the energy required to fracture a skull has been studied and calculated to be in range of this and it's far easier to punch the middle/upper areas of the body than the bottom.
It should be noted that some bones are far easier to break than others due to their adaptive quality, shape and size. If the bone didn't make itself strong and/or sizable enough, it wouldn't count anywhere 10-B and above. That's not mentioning fish bones, an old person's bones, and the
smallest/
weakest bones can't withstand anywhere 10-B and above.
As for other severe bone-breaking feats, I'm not saying all bone breaking is that unimpressive. If the bone breaking is incredibly severe (example: twisting an arm bone to where it massively deforms an arm, severely crushing a part of the skull, severely twisting a backbone in an unnatural way), it would be absolutely be comparable to the low-end 375 J of breaking a human femur. It's just that when dealing with human bones and the like in fiction, we have to take into account bone strength and bone damage severity.