title: Advantages of Direct Insertion of a Straight Probe Without a Guide Tube During Anterior Odontoid Screw Fixation of Odontoid Fractures.
abstract: METHODS
  A retrospective cohort study.
  
  
  OBJECTIVE
  The aim of this study was to compare the anterior odontoid screw fixation (AOSF) with a guide tube or with a straight probe.
  
  
  BACKGROUND
  AOSF associates with several complications, including malpositioning, fixation loss, and screw breakage. Screw pull-out from the C2 body is the most common complication.
  
  
  METHODS
  All consecutive patients with type II or rostral shallow type III odontoid fractures who underwent AOSFs during the study period were enrolled retrospectively. The guide-tube AOSF method followed the standard published method except C3 body and C2-3 disc annulus rimming was omitted to prevent disc injury; instead, the guide tube was anchored at the anterior inferior C2 vertebra corner. After 2 screw pull-outs, the guide-tube cohort was analyzed to identify the cause of instrument failure. Thereafter, the straight-probe method was developed. A guide tube was not used. A small pilot hole was made on the most anterior side of the inferior endplate, followed by insertion of a 2.5 mm straight probe through the C2 body. Non-union and instrument failure rates and screw-direction angles of the guide-tube and straight-probe groups were recorded.
  
  
  RESULTS
  The guide-tube group (n = 13) had 2 screw pull-outs and 1 non-union. The straight-probe group (n = 8) had no complications and significantly larger screw-direction angles than the guide-tube group (60.5 ± 4.63 vs. 54.8 ± 3.82 degrees; P = 0.047).
  
  
  CONCLUSIONS
  Straight-probe AOSF yielded larger direction angles without injuring bone and disc. Complications were absent. The procedure was easier than guide-tube AOSF and assured sufficient engagement, even in horizontal fracture orientation cases.
  
  
  METHODS
  3.
authors.affiliation: *Department of Neurological Surgery†Department of Neurology‡Department of Anesthesiology§Department of Emergency Medicine, Gangneung Asan Hospital, University of Ulsan College of Medicine, Gangneung¶Department of Neurological Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul||Department of Neurological Surgery, Gyeongsang National University School of Medicine, Jinju, Korea.
authors.forename: Jin Hoon
authors.initials: JH
authors.lastname: Park
authors.forename: Dong-Ho
authors.initials: DH
authors.lastname: Kang
authors.forename: Moon Kyu
authors.initials: MK
authors.lastname: Lee
authors.forename: Byoungwoo
authors.initials: B
authors.lastname: Yoo
authors.forename: Sang Ku
authors.initials: SK
authors.lastname: Jung
authors.forename: Soo-Hyun
authors.initials: SH
authors.lastname: Hwang
authors.forename: Jeoung Hee
authors.initials: JH
authors.lastname: Kim
authors.forename: Sunkyu
authors.initials: S
authors.lastname: Oh
authors.forename: Eun Jung
authors.initials: EJ
authors.lastname: Lee
authors.forename: Sang Ryong
authors.initials: SR
authors.lastname: Jeon
authors.forename: Sung Woo
authors.initials: SW
authors.lastname: Roh
authors.forename: Seung Chul
authors.initials: SC
authors.lastname: Rhim
mesh_terms: D000328:Adult; D000368:Aged; D001863:Bone Screws; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery; D015331:Cohort Studies; D005260:Female; D005593:Fracture Fixation, Internal / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D008297:Male; D008875:Middle Aged; D009809:Odontoid Process / Q000000981:diagnostic imaging / Q000601:surgery*; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000517:prevention & control*; D012189:Retrospective Studies; D016103:Spinal Fractures / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000601:surgery*; D055815:Young Adult