Trepanning is the oldest surgery know to man. It comes down to boring, cutting, and scraping open holes in a human skull. It was practised as early as 10,000 B.C. in Europe, South America, and some parts of Northern Africa.
If you had been transported to the 19th century, suffered from a headache and you wanted to be trepanned (have a hole drilled in your head), the best place to have it done would be in Papua New Guinea. When they did this they sealed the hole with coconut milk which was sterile and thus reduced infection.
In London, 78% of trepanning procedures resulted in death from infection rather than having a hole in the head. Trepanning is so far as we know the earliest form of surgery. We know people survived it because the bone and tissue healed around skulls found in archaeological digs. The earliest known forms involved getting the patient’s head between your legs and scraping away the hair, flesh and bone with a sharp stone.