title: A Novel Patient-Specific Drill Guide Template for Pedicle Screw Insertion into the Subaxial Cervical Spine Utilizing Stereolithographic Modelling: AnIn VitroStudy.
abstract: METHODS
  Cadaveric study.
  
  
  OBJECTIVE
  The purpose of this study was to assess the accuracy and feasibility of cervical pedicle screw (CPS) insertion into the subaxial cervical spine placed using a patient-specific drill guide template constructed from a stereolithographic model.
  
  
  BACKGROUND
  CPS fixation is an invaluable tool for posterior cervical fixation because of its biomechanical advantages. The major drawback is its narrow corridor that allows very little clearance for neural and vascular injuries.
  
  
  METHODS
  Fifty subaxial pedicles of the cervical vertebrae from five cadavers were scanned into thin slices using computed tomography (CT). Digital imaging and communications in medicine images of the cadaver spine were digitally processed and printed to scale as a three-dimensional (3D) model. Drill guide templates were manually moulded over the 3D-printed models incorporating pins inserted in the pedicles. The drill guide templates were used for precise placement of the drill holes in the pedicles of cadaveric specimens for pedicle screw fixation.
  
  
  RESULTS
  The instrumented cadaveric spines were subjected to CT to assess the accuracy of our pedicle placement by an external observer. Our patient-specific drill guide template had an accuracy of 94%.
  
  
  CONCLUSIONS
  The use of a patient-specific drill guide constructed using stereolithography improved the accuracy of CPS placement in a cadaveric model.
authors.affiliation: Section of Spine Surgery, Department of Orthopedics, Philippine General Hospital, University of the Philippines, Manila, Philippines.
authors.forename: Rafael Cruz
authors.initials: RC
authors.lastname: Bundoc
authors.affiliation: Department of Orthopedics, Philippine General Hospital, University of the Philippines, Manila, Philippines.
authors.forename: Giorgio De Guzman
authors.initials: GG
authors.lastname: Delgado
authors.affiliation: Section of Spine Surgery, Department of Orthopedics, Philippine General Hospital, University of the Philippines, Manila, Philippines.
authors.forename: Samuel Arsenio Munoz
authors.initials: SA
authors.lastname: Grozman
keywords: Cervical pedicle screw fixation; Patient-specific surgical template; Stereolithography; Subaxial cervical spine; Three-dimensional printing