title: Computed tomography-guided C2 pedicle screw placement for treatment of unstable hangman fractures.
abstract: METHODS
  Case series and description of technique.
  
  
  OBJECTIVE
  The purpose of this study was to evaluate the feasibility and accuracy of inserting pedicle screws in unstable Hangman fracture cases by using intraoperative CT (O-arm) based navigation.
  
  
  BACKGROUND
  Hangman fracture, also known as traumatic spondylolisthesis of the C2, is defined as a fracture involving the lamina, articular facets, pedicles, or pars of the axis vertebra. Opinions vary regarding the optimal treatment of unstable Hangman fractures. Some authors have recommended the use of rigid orthosis, whereas others have recommended surgical stabilization. The peculiar anatomy of the upper cervical spine is highly variable, and the presence of surrounding neurovascular structures makes pedicle screw fixation even more technically challenging. The advent of intraoperative 3-dimensional navigation systems permits safe and accurate instrumentation of the cervical spine.
  
  
  METHODS
  Ten patients with unstable Hangman fracture, with age ranging from 17 years to 81 years, were operated under O-arm-based navigation, and screw position was confirmed with intraoperative computed tomographic scan.
  
  
  RESULTS
  A total of 52 screws were inserted under O-arm guidance: 20 in C2 pedicle, 20 in C3 lateral mass, and rest in C4 lateral mass. Screw misplacement was seen in only 1 C2 pedicle screw (1 of 20, 5%). No new-onset neurological deficit developed in any of the patients. Follow-up ranged from 3 months to 21 months. Bony fusion was achieved in all. Full rotation was preserved at C1-C2 joint. All the patients (50%) with neurological deficits before surgery improved after surgery.
  
  
  CONCLUSIONS
  This series demonstrates that C2 pedicle screws can be put with precision under O-arm-guided navigation, and intraoperative computed tomographic scan can confirm position of screws. Patients can be operated and mobilized early with negligible risk of screw misplacement, with preservation of motion at the C1-C2 joint.
  
  
  METHODS
  4.
authors.affiliation: From the Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Pankaj Kumar
authors.initials: PK
authors.lastname: Singh
authors.forename: Kanwaljeet
authors.initials: K
authors.lastname: Garg
authors.forename: Duttaraj
authors.initials: D
authors.lastname: Sawarkar
authors.forename: Deepak
authors.initials: D
authors.lastname: Agarwal
authors.forename: Guru Dutta
authors.initials: GD
authors.lastname: Satyarthee
authors.forename: Deepak
authors.initials: D
authors.lastname: Gupta
authors.forename: Sumit
authors.initials: S
authors.lastname: Sinha
authors.forename: Shashank Sarad
authors.initials: SS
authors.lastname: Kale
authors.forename: Bhawani Shankar
authors.initials: BS
authors.lastname: Sharma
mesh_terms: D000293:Adolescent; D000328:Adult; D000369:Aged, 80 and over; D002574:Cervical Vertebrae / Q000601:surgery*; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods; D065289:Pedicle Screws; D015203:Reproducibility of Results; D016103:Spinal Fractures / Q000601:surgery*; D013168:Spondylolisthesis / Q000601:surgery*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome; D055815:Young Adult