Well like I said before Im not an expert on pacman frogs but again with what I know about MBD. He should survive as long as he starts eating again. You should still dust with calcium with each feeding as it will help strengthn the bones some and reduce some pain. But again it does look like a pretty bad cause of MBD and MBD is a disease to which after a certain point it will but even with dusting the effects will never fully be healed. Hopefully someone else will be of more help. I only know so much