title: Accuracy of intraoperative computed tomography image-guided surgery in placing pedicle and pelvic screws for primary versus revision spine surgery.
abstract: OBJECTIVE
  Revision spine surgery, which is challenging due to disrupted anatomy, poor fluoroscopic imaging, and altered tactile feedback, may benefit from CT image-guided surgery (CT-IGS). This study evaluates accuracy of CT-IGS-navigated screws in primary versus revision spine surgery.
  
  
  METHODS
  Pedicle and pelvic screws placed with the O-arm in 28 primary (313 screws) and 33 revision (429 screws) cases in which institutional postoperative CT scans were available were retrospectively reviewed for placement accuracy. Screw accuracy was categorized as 1) good (< 1-mm pedicle breach in any direction or "in-out-in" thoracic screws through the lateral thoracic pedicle wall and in the costovertebral joint); 2) fair (1- to 3-mm breach); or 3) poor (> 3-mm breach).
  
  
  RESULTS
  Use of CT-IGS resulted in high rates of good or fair screws for both primary (98.7%) and revision (98.6%) cases. Rates of good or fair screws were comparable for the following regions: C7-T3 at 100% (good or fair) in primary versus 100% (good or fair) in revision; T4-9 at 96.8% versus 100%; T10-L2 at 98.2% versus 99.3%; L3-5 at 100% versus 99.2%; and pelvis at 98.7% versus 98.6%, respectively. On the other hand, revision sacral screws had statistically significantly lower rates of good placement compared with primary (100% primary vs 80.6% revision, p = 0.027). Of these revision sacral screws, 11.1% had poor placement, with bicortical screws extending > 3 mm beyond the anterior cortex. Revision pelvic screws demonstrated the highest rate of fair placement (28%), with the mode of medial breach in all cases directed into the sacral-iliac joint.
  
  
  CONCLUSIONS
  In the cervical, thoracic, and lumbar spine, CT-IGS demonstrated comparable accuracy rates for both primary and revision spine surgery. Use of 3D imaging of the bony pedicle anatomy appears to be sufficient for the spine surgeon to overcome the difficulties associated with instrumentation in revision cases. Although the bony structures of sacral pedicles and pelvis are relatively larger, the complexity of local anatomy was not overcome with CT-IGS, and an increased trend toward inaccurate screw placement was demonstrated.
authors.affiliation: Departments of Neurosurgery and.
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Hsieh
authors.forename: Doniel
authors.initials: D
authors.lastname: Drazin
authors.forename: Alexander O
authors.initials: AO
authors.lastname: Firempong
authors.forename: Robert
authors.initials: R
authors.lastname: Pashman
authors.forename: J Patrick
authors.initials: JP
authors.lastname: Johnson
authors.forename: Terrence T
authors.initials: TT
authors.lastname: Kim
mesh_terms: D001863:Bone Screws; D006801:Humans; D021621:Imaging, Three-Dimensional; D016343:Monitoring, Intraoperative / Q000379:methods; D019635:Neurosurgical Procedures; D012189:Retrospective Studies; D013131:Spine / Q000601:surgery*; D025321:Surgery, Computer-Assisted / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods; D016896:Treatment Outcome