And Dreamora already answered that when he said
What you suggest, however, makes no sense to me. You seem to be trying to do precisely the opposite of what I would be doing if I wanted rag doll physics. Perhaps it's just me, but I'd be wanting to attach my vertices to bones in the modeller and then control the bone positions in code. Which you can do. But for whatever reason, that doesn't seem to be your aim.
Especially you can not assign vertices to bones in realtime.
What you suggest, however, makes no sense to me. You seem to be trying to do precisely the opposite of what I would be doing if I wanted rag doll physics. Perhaps it's just me, but I'd be wanting to attach my vertices to bones in the modeller and then control the bone positions in code. Which you can do. But for whatever reason, that doesn't seem to be your aim.