title: Accuracy of fluoroscopy versus computer-assisted navigation for the placement of anterior cervical pedicle screws.
abstract: METHODS
  Randomized laboratory cadaver study.
  
  
  OBJECTIVE
  The objective of this study was to determine the accuracy of anterior transpedicular screw placement in the cervical spine using conventional fluoroscopy versus computer-assisted navigation.
  
  
  BACKGROUND
  Traditionally, global cervical instability has required anterior and posterior fixation due to the superior biomechanical stability of circumferential constructs. Anterior transpedicular screws (ATPS) have recently been advocated as a single surgical approach. Current clinical publications report using fluoroscopic guidance for screw placement. Computer-assisted navigation (CAN) systems have demonstrated enhanced accuracy of pedicle screw placement at all spine levels but have not been assessed for ATPS.
  
  
  METHODS
  The anterior vertebrae of 9 fresh frozen cadaver cervical spines were exposed, preserving the lateral and posterior soft tissue envelope. Nine practicing spine surgeons placed 2.0-mm titanium anterior transpecidular Kirschner wires into the C3-T1 pedicles bilaterally using fluoroscopy or CAN guidance. Specimens were imaged by computed tomography and virtual screws were overlaid on the K-wires. Targeting accuracy was compared between the 2 techniques in all planes using a 5-level grading scale.
  
  
  RESULTS
  The percentage of acceptable screw placements for fluoroscopy and CAN was 42.6% and 66.7%, respectively (P = 0.012). Catastrophic screw placement (grade 3 or 4) was 33.3% for fluoroscopy and 16.7% for CAN. In the multivariable model, the accuracy rate was 67% lower for fluoroscopy than for CAN after controlling for other factors (odds ratio: 0.33, 95% confidence interval: 0.14-0.79).
  
  
  CONCLUSIONS
  The accuracy of CAN-guided placement of K-wires for ATPS was superior to placement under fluoroscopic guidance, demonstrating statistically more acceptable screw placements and significantly less catastrophic virtual screws. However, malposition was still high, with potential for vertebral artery and neurological injury in a clinical setting. Further advancement in current ATPS techniques is warranted prior to widespread implementation in a patient setting.
  
  
  METHODS
  N/A.
authors.affiliation: From the Departments of *Orthopaedic Surgery and Rehabilitation and †Internal Medicine, Division of Geriatric Medicine, The University of Texas Medical Branch, Galveston, TX.
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Patton
authors.forename: Randal P
authors.initials: RP
authors.lastname: Morris
authors.forename: Yong-Fang
authors.initials: YF
authors.lastname: Kuo
authors.forename: Ronald W
authors.initials: RW
authors.lastname: Lindsey
mesh_terms: D001696:Biomechanical Phenomena; D001863:Bone Screws; D001864:Bone Wires; D002102:Cadaver; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D005471:Fluoroscopy / Q000379:methods*; D006801:Humans; D066298:In Vitro Techniques; D016268:Internal Fixators; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000601:surgery*; D019635:Neurosurgical Procedures / Q000295:instrumentation / Q000379:methods; D019637:Orthopedic Procedures / Q000295:instrumentation / Q000379:methods; D025321:Surgery, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed