Mandible and maxilla (bimaxillary), procedure for any combination of arch reshaping, advancement, retrusion or tilting of, involving complex segmental osteotomies, with or without standard osteotomies, including genioplasty (if performed) and fixation by any means (including application of distractors if used)—conjoint surgery, principal specialist surgeon, one service per patient on the same occasion (H) (Anaes.) (Assist.)