title: Unilateral Spinous Process Noncovering Hook Type Patient-specific Drill Template for Thoracic Pedicle Screw Fixation: A Pilot Clinical Trial and Template Classification.
abstract: METHODS
  Prospective clinical pilot study.
  
  
  OBJECTIVE
  To confirm the accuracy of thoracic pedicle screw placement by using the unilateral spinous noncovering hook type patient-specific drill template (PSDT) made through rapid prototyping (RP) and to analyze previously reported PSDT designs and their characteristics.
  
  
  BACKGROUND
  Pedicle screw fixation is the most common form of the posterior instrumentation of the thoracic and lumbar spine. Various techniques have been introduced to improve pedicle screw placement. Among them PSDT with a preplanned trajectory has been considered a promising solution; however, we don't have consensus on proper character of the template.
  
  
  METHODS
  Preoperative spiral three-dimensional (3D) computed tomography (CT) was performed on the thoracic spine. The images were stored in DICOM format and transferred to a workstation running MIMICS 17.0 software to generate a 3D reconstruction template for the desired thoracic vertebra. The accurate trajectory and screw diameter and length were calculated with UG Imageware 12.1. The guide template was sterilized and used intraoperatively to assist with the placement of thoracic pedicle screws. After all pedicle trajectory screws had been inserted. We reviewed 12 previous reports and classified them according to the shape and system of PSDT that met the inclusion criteria of the review.
  
  
  RESULTS
  Ten screws were placed by using the PSDT without violating the single laminar cortex. There was no violation of the spinal canal or the cortex of pedicle on postoperative CT scans. The results of 13 PSDT types included in the current study suggested that there is no significant difference in accuracy between the PSDTs.
  
  
  CONCLUSIONS
  The unilateral spinous process noncovering hook type PSDT made through RP provided an accurate trajectory for the thoracic vertebra, and the classification of PSDT in this study could be helpful for further studies.
  
  
  METHODS
  5.
authors.affiliation: College of Medicine, Konyang University, Boston, MA.
authors.forename: Sang B
authors.initials: SB
authors.lastname: Kim
authors.affiliation: College of Medicine, Konyang University, Boston, MA.
authors.forename: Yougun
authors.initials: Y
authors.lastname: Won
authors.affiliation: College of Medicine, Konyang University, Boston, MA.
authors.forename: Hyun Jin
authors.initials: HJ
authors.lastname: Yoo
authors.affiliation: College of Medicine, Konyang University, Boston, MA.
authors.forename: Lee J
authors.initials: LJ
authors.lastname: Sin
authors.affiliation: Department of Orthopedic Surgery, Emory University, Atlanta, GA.
authors.forename: John M
authors.initials: JM
authors.lastname: Rhee
authors.affiliation: School of Biomedical Engineering, Konyang University, Boston, MA.
authors.forename: Sang W
authors.initials: SW
authors.lastname: Lee
authors.affiliation: College of Medicine, Konyang University, Boston, MA.
authors.forename: Gi-Soo
authors.initials: GS
authors.lastname: Lee
mesh_terms: D006801:Humans; D021621:Imaging, Three-Dimensional; D019637:Orthopedic Procedures / Q000295:instrumentation / Q000379:methods; D065289:Pedicle Screws; D010865:Pilot Projects; D011446:Prospective Studies; D025321:Surgery, Computer-Assisted / Q000295:instrumentation / Q000379:methods; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery; D014057:Tomography, X-Ray Computed