title: Accuracy of a dynamic surgical guidance probe for screw insertion in the cervical spine: a cadaveric study.
abstract: A fresh frozen cadaver study was conducted.
  
  
  
  To report the cortical breach rate using the dynamic surgical guidance (DSG) probe versus traditional freehand technique for cervical lateral mass, cervical pedicle and cervical laminar screws.
  
  
  
  Nine male fresh frozen cadaveric torsos were utilized for this study. Each investigator was assigned three specimens that were randomized by fixation point, side and order of technique for establishing a screw pilot hole. The technique for screw hole preparation utilized was either a DSG probe in the "on" mode or in the "off" mode using a freehand technique popularized by Lenke et al. Levels instrumented included C1 lateral mass, C2 pedicle screws and lamina screws, and C6-T1 pedicle screws. Fluoroscopy and other navigational assistance were not used for screw hole preparation or screw insertion. All specimens were CT imaged following insertion of all screws. A senior radiologist evaluated all scans and determined that a misplaced screw was a breach of ≥2 mm.
  
  
  
  A total of 104 drillings were performed, 52 with DSG and 52 without DSG There were 68 total pedicle drillings, 34 in each group. There were 18 drillings in the lamina and lateral mass. There was no significant difference between surgeons or between the left and right side. All breaches were in the pedicle, and none in the lamina or lateral mass. The breach rate for PG "on" was 6/68 = 8.96% (95% CI 3.69, 19.12%). The breach rate for PG "off" was 20/68 = 29.41% (95% CI 19.30, 41.87%). Of the 20 pedicle breaches in the non-DSG group, 7 were lateral and superior, 8 were lateral, 4 medial and 1 inferior. Of the six pedicle breaches in the DSG group, two were lateral/superior, two were lateral and two were medial in the pedicle.
  
  
  
  The dynamic surgical guidance probe is a safe tool to assist the surgeon with screw placement in the cervical spine. Additionally, the DSG potentially avoids the cumulative risks associated with fluoroscopy and provides real-time feedback to the surgeon allowing correction at the time of breach. Level of evidence Level IV.
authors.affiliation: , 2001 Randolph Rd, Charlotte, NC, 28207, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Dixon
authors.affiliation: OrthoCarolina Spine Center, Attn: Annette Wilson, 2001 Randolph Rd, Charlotte, NC, 28207, USA. bruce.darden@orthocarolina.com.
authors.forename: Bruce
authors.initials: B
authors.lastname: Darden
authors.affiliation: , Av. Diagonal 491, 6º1ª, 08029, Barcelona, Spain.
authors.forename: Jose
authors.initials: J
authors.lastname: Casamitjana
authors.affiliation: Spine Surgery Unit, Hospital Exequiel Gonzalez Cortés, Clínica Bicentenario, Clinica Avansalud and Fundación Médica, Santiago, Chile.
authors.forename: Karen A
authors.initials: KA
authors.lastname: Weissmann
authors.affiliation: Orthopedic Surgery Department, Universidad de Chile, Santiago, Chile.
authors.forename: San
authors.initials: S
authors.lastname: Cristobal
authors.affiliation: Fort Wayne Radiology, 3707 New Vision Drive, Fort Wayne, IN, 46845, USA.
authors.forename: David
authors.initials: D
authors.lastname: Powell
authors.affiliation: , 2001 Randolph Rd, Charlotte, NC, 28207, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Baluch
mesh_terms: D002574:Cervical Vertebrae / Q000601:surgery; D006801:Humans; D008297:Male; D065289:Pedicle Screws; D011897:Random Allocation; D013123:Spinal Fusion / Q000379:methods*; D025321:Surgery, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed
keywords: C2 pedicle screw; C7 pedicle screw; Cervical spine; Cortical breach; Dynamic surgical guidance; Electrical conductivity; Fluoroscopy; Lamina screw; Lateral mass; Lateral mass screw