title: A novel cost-effective computer-assisted imaging technology for accurate placement of thoracic pedicle screws.
abstract: OBJECTIVE
  Use of computer-assisted spine surgery (CASS) technologies, such as navigation systems, to improve the accuracy of pedicle screw (PS) placement is increasingly popular. Despite of their benefits, previous CASS systems are too expensive to be ubiquitously employed, and more affordable and portable systems are desirable. The aim of this study was to introduce a novel and affordable computer-assisted technique that 3-dimensionally visualizes anatomical features of the pedicles and assists in PS insertion. The authors have termed this the 3D-visual guidance technique for inserting pedicle screws (3D-VG TIPS).
  
  
  METHODS
  The 3D-VG technique for placing PSs requires only a consumer-class computer with an inexpensive 3D DICOM viewer; other special equipment is unnecessary. Preoperative CT data of the spine were collected for each patient using the 3D-VG TIPS. In this technique, the anatomical axis of each pedicle can be analyzed by volume-rendered 3D models, as with existing navigation systems, and both the ideal entry point and the trajectory of each PS can be visualized on the surface of 3D-rendered images. Intraoperative guidance slides are made from these images and displayed on a TV monitor in the operating room. The surgeon can insert PSs according to these guidance slides. The authors enrolled 30 patients with adolescent idiopathic scoliosis (AIS) who underwent posterior fusion with segmental screw fixation for validation of this technique.
  
  
  RESULTS
  The novel technique allowed surgeons, from office or home, to evaluate the precise anatomy of each pedicle and the risks of screw misplacement, and to perform 3D preoperative planning for screw placement on their own computer. Looking at both 3D guidance images on a TV monitor and the bony structures of the posterior elements in each patient in the operating theater, surgeons were able to determine the best entry point for each PS with ease and confidence. Using the current technique, the screw malposition rate was 4.5% in the thoracic region in corrective surgery for AIS.
  
  
  CONCLUSIONS
  The authors found that 3D-VG TIPS worked on a consumer-class computer and easily visualized the ideal entry point and trajectory of PSs in any operating theater without costly special equipment. This new technique is suitable for preoperative planning and intraoperative guidance when performing reconstructive surgery with PSs.
authors.affiliation: Department of Orthopaedic Surgery, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Abe
authors.forename: Manabu
authors.initials: M
authors.lastname: Ito
authors.forename: Kuniyoshi
authors.initials: K
authors.lastname: Abumi
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Kotani
authors.forename: Hideki
authors.initials: H
authors.lastname: Sudo
authors.forename: Akio
authors.initials: A
authors.lastname: Minami
mesh_terms: D000293:Adolescent; D001863:Bone Screws; D003362:Cost-Benefit Analysis; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D011859:Radiography; D012600:Scoliosis / Q000000981:diagnostic imaging / Q000601:surgery*; D013123:Spinal Fusion / Q000191:economics / Q000295:instrumentation / Q000379:methods*; D025321:Surgery, Computer-Assisted / Q000191:economics / Q000379:methods*; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*