So where the hell has this 4 inch scar on my top right thigh come from ?

During the latest operation they had to be a bit more aggressive in removing damaged tissue
As a result they broke through the dura (which is part of the thin membrane that surrounds the brain and spinal cord)
There was a leak of cerebrospinal fluid
Therefore the leak needed to "Plugged"
They used fat from my thigh to patch up the hole in the Dura