title: Simulation-guided navigation for vector control in pediatric mandibular distraction osteogenesis.
abstract: OBJECTIVE
  Navigation technology has given surgeons the capacity to know precisely where their instruments are during surgery, and simulation-guided navigation is a surgical method which is based on the use of navigation technology linked to 3D virtual surgery simulation. The aim of the present study was to evaluate the absolute accuracy of simulation-guided navigation as an aid to reproduce the planned position of the distraction device vector in pediatric mandibular distraction osteogenesis.
  
  
  METHODS
  We retrospectively evaluated seven patients affected by unilateral (3 pts.) or bilateral (4 pts.) mandibular hypoplasia and treated with this method between 2012 and 2014 at the Maxillofacial Surgery Unit of the University of Bologna, Italy. All patients were enrolled for mandibular distraction using internal unidirectional devices (11 distraction devices implanted overall). Patients were studied through a complete three-dimensional workflow, which led to obtaining a virtual reconstruction of the facial bones and the simulation of the distraction device positioning using a specific experimental software. The surgical planning was loaded on the navigation system and the distraction device was placed following the virtual plan, which is displayed on the navigation system as a guide and tracked with the navigation instruments.
  
  
  RESULTS
  We analyzed the outcome comparing the recorded three-dimensional coordinates of the achieved distractor position and the three-dimensional coordinates of the planned distractor position. Among the eleven placed distractors, we found a mean angular error of 3.74° ± 3.30° on the axial axis (yaw) and of 6.27° ± 5.32° on the sagittal axis (pitch), while median angular errors are 3.72° on the axial axis (yaw) and 4.08° on the sagittal axis (pitch).
  
  
  CONCLUSIONS
  Our preliminary experience seems to support that simulation-guided navigation for vector control in mandibular distraction osteogenesis could be a useful procedure for reproducing the virtually planned outcome. Nevertheless, our results cannot be considered completely satisfactory. There is a lot of room to improve accuracy and errors seem to depend mainly on the soft tissues interference during distractor placement.
authors.affiliation: Oral and Maxillofacial Surgery Unit, S. Orsola-Malpighi University Hospital (Head: Prof. Claudio Marchetti), University of Bologna, Italy. Electronic address: giovanni.badiali@unibo.it.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Badiali
authors.affiliation: EndoCAS (Head: Prof. Mauro Ferrari), University of Pisa, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Cutolo
authors.affiliation: Computational Bioengineering Lab (Head: Fulvia Taddei), Rizzoli Orthopedic Institute, Bologna, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Roncari
authors.affiliation: Oral and Maxillofacial Surgery Unit, S. Orsola-Malpighi University Hospital (Head: Prof. Claudio Marchetti), University of Bologna, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Marchetti
authors.affiliation: Oral and Maxillofacial Surgery Unit, S. Orsola-Malpighi University Hospital (Head: Prof. Claudio Marchetti), University of Bologna, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Bianchi
mesh_terms: D002648:Child; D002675:Child, Preschool; D003198:Computer Simulation; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008334:Mandible / Q000002:abnormalities* / Q000601:surgery*; D019857:Osteogenesis, Distraction / Q000379:methods*; D012189:Retrospective Studies; D012984:Software; D025321:Surgery, Computer-Assisted / Q000379:methods*; D013577:Syndrome; D016896:Treatment Outcome
keywords: Computer assisted image analysis; Computer-assisted surgery; Congenital abnormality; Distraction osteogenesis; Simulation-guided navigation