I'm guessing it was Klinik Pyramide in Zurich, Switzerland (Dr Albino Triaca + Dr Daniel Brusco). This is pretty much the best place in Europe for surgery and they are the experts for the chin wing procedure. They even do stuff like Wilckodontics and malar osteotomy as well as releasing papers on DO. If I could afford it, this is where I would be going
The gonial angle change is impressive, in this case I guess the chin wing osteotomy goes all the way to the back of the mandible. They would have rotated the back section downwards (CCW of a section rather than a jaw), that's how you get the change in gonial angle. They are lengthening the back of the ramus but it is a split osteotomy, not full thickness (I think, at least it looks that way in the diagrams)
He may have had a BSSO but the result could be from a cleverly done chin wing. My guess is that they took the section, took out some vertical height at the front, moved it slightly backwards and rotated the posterior down (CCW)
I reckon we are going to see more and more surgeons training in this procedure. Give it 5 years and it will be much more commonly done
