title: Application of Unilateral C2 Translaminar Screw in the Treatment for Atlantoaxial Instability as an Alternative or Salvage of Pedicle Screw Fixation.
abstract: OBJECTIVE
  To analyze the clinical outcomes of our experience with the unilateral C2 translaminar screw technique and evaluate its feasibility as an alternative or salvage of the pedicle screw.
  
  
  METHODS
  Eleven consecutive adult patients with atlantoaxial instability who underwent hybrid fixation techniques using unilateral translaminar screw combined with contralateral C2 pedicle screw and bilateral C1 LMS via posterior arch from January 2010 to December 2013 were retrospectively investigated. The surgical techniques and treatment procedures were described, and clinical symptoms, neurologic function, and imaging appearance were evaluated.
  
  
  RESULTS
  The average age in our series was 40.9 years. No vascular or neurologic injuries occurred. No hardware failure or breach of C2 lamina or pedicle was observed in postoperative radiographs or computed tomography scans. Good bone union was achieved in all patients. There were no cases of screw pullout or pseudarthrosis.
  
  
  CONCLUSIONS
  Patients with variant vertebral artery or osseous anomaly are good candidates for the hybrid translaminar screw technique as an alternative to or salvage of C2 pedicle screw.
authors.affiliation: Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai, People's Republic of China.
authors.forename: Shiyao
authors.initials: S
authors.lastname: Du
authors.affiliation: Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai, People's Republic of China. Electronic address: nibinsmmu@163.com.
authors.forename: Bin
authors.initials: B
authors.lastname: Ni
authors.affiliation: Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai, People's Republic of China.
authors.forename: Xuhua
authors.initials: X
authors.lastname: Lu
authors.affiliation: Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai, People's Republic of China.
authors.forename: Ning
authors.initials: N
authors.lastname: Xie
authors.affiliation: Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai, People's Republic of China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Guo
authors.affiliation: Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai, People's Republic of China.
authors.forename: Qunfeng
authors.initials: Q
authors.lastname: Guo
authors.affiliation: Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai, People's Republic of China.
authors.forename: Jun
authors.initials: J
authors.lastname: Yang
authors.affiliation: Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai, People's Republic of China.
authors.forename: Fei
authors.initials: F
authors.lastname: Chen
mesh_terms: D000293:Adolescent; D000328:Adult; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D002574:Cervical Vertebrae / Q000601:surgery; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D016268:Internal Fixators; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D065289:Pedicle Screws; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods*; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D064232:Visual Analog Scale; D055815:Young Adult
keywords: Atlantoaxial articulation; Instability; Internal fixators; Spinal fusion