I really hope a pulped appendage does NOT fall off. You'd see your war duckling fleeing from his sentry post dragging a useless bag of wing bone paste from his shoulder after being knocked back by the goblin maceman.
Also, since the BONE layer should provide only a fraction of its original resistance, it should be easier to, subsequently, cause the area to sail off in an arc.
I am actually hoping that "pulp" isn't, as a state, a thing, like bruised or shattered. I'd like to think it's more detail and/or analysis, as well as persistence, in the tissue damage data. Thereby, IF Urist McUnluckySwordswarf's Right Arm has had 8 of the wrist bones broken, as well as a cumulative sum of 8 fractures between both the radius and ulna, and each has at least two breaks, THEN Urist McUnluckySwordsdwarf's Right Arm has been pulped, gaining a PULPY flag, and is no longer eligible for further raises.
If that is true, then it may be possible to treat, on a living dwarf, PULPY extremities (limited to HAND, FOOT, UPPER/LOWER ARM/LEG ?) with metal rods and Surgery, eventually healing to a maximum of INHIBITED perhaps, with much scarring.
I can't say if that's what is on the plate for this release, but that seems like what would be the eventual goal for deep, detailed modeling.