title: Prospective evaluation of thoracic pedicle screw placement using fluoroscopic imaging.
abstract: BACKGROUND
  In this prospective 18-month study, 29 patients underwent posterior thoracic instrumentation with placement of 209 transpedicular screws guided by intraoperative fluoroscopic imaging and anatomic landmarks. We assessed the safety, accuracy, complications, and early stability of this technique.
  
  
  METHODS
  Pedicle and pedicle-rib units were measured, and screw cortical penetrations were graded on anatomy and depth of penetration. All 29 patients underwent preoperative computed tomographic (CT) imaging, and 28 underwent postoperative CT imaging (199/209 screws).
  
  
  RESULTS
  From T2 to T12, screw diameters were >or=5 mm with mean medial screw angulation measuring 20-25 degree. Of the 209 screws placed from T1 to T12, 111 had diameters greater than or equal to the pedicle width. From T3 to T9, the mean diameter of the pedicle screws exceeded the mean pedicle width. Lateral pedicle wall penetration occurred significantly more often than superior, inferior, and medial pedicle wall penetrations and anterolateral vertebral body penetration. Five of six high-risk screw penetrations occurred in one patient when intraoperative technique was compromised. We observed no new postoperative neurologic deficits, visceral injuries, or pedicle screw instrumentation failures. The three high-risk anterolateral vertebral body penetrations at T1 and T2 were associated with a significantly decreased mean screw transverse angle; the three high-risk medial pedicle wall penetrations occurring from T3 to T9 were associated with a significantly increased mean screw transverse angle. Among all 26 patients available at postoperative follow-up (mean 11.9 months), the mean loss of kyphosis correction was 2.0 degree.
  
  
  CONCLUSIONS
  Guided by intraoperative fluoroscopic imaging and anatomic landmarks, thoracic pedicle screws can be placed safely. Early clinical follow-up reveals excellent results with minimal loss of kyphosis correction.
authors.affiliation: Department of Neurosurgery, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0515, USA. editor@mayfieldclinic.com
authors.forename: Charles
authors.initials: C
authors.lastname: Kuntz
authors.forename: P Colby
authors.initials: PC
authors.lastname: Maher
authors.forename: Nicholas B
authors.initials: NB
authors.lastname: Levine
authors.forename: Ryu
authors.initials: R
authors.lastname: Kurokawa
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001863:Bone Screws; D005260:Female; D005471:Fluoroscopy; D005500:Follow-Up Studies; D006801:Humans; D007738:Kyphosis / Q000000981:diagnostic imaging / Q000601:surgery; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D011446:Prospective Studies; D013122:Spinal Diseases / Q000000981:diagnostic imaging* / Q000601:surgery*; D013123:Spinal Fusion / Q000295:instrumentation / Q000379:methods*; D016896:Treatment Outcome