Say Sorry to your brother - what a mess.
The reason why it kept on splitting was that the wound was infected, or became infected. It also sounds as tho' there was a gap - tissue loss - and so the clever surgeons take the skin to cover the injury from somewhere else and then do a bit of slipping and sliding over the healthy site which is likely to heal better and quicker.
Was the skull fractured ( bone broken) ? If both the bone and the skin over it was broken then it counts as a compound fracture and these can be very troublesome.
These injuries are uncommon but foreseeable - hope he is better.
and ... sorry I dont know about the sentence.