title: Posterior Open Reduction and Interlaminae Compression Fusion for Os Odontoideum with Atlantoaxial Dislocation.
abstract: OBJECTIVE
  To evaluate the outcome of posterior open reduction and interlaminae compression fusion using a screw-rod system combined with a structural iliac bone graft in the treatment of atlantoaxial dislocation (AAD) secondary to os odontoideum.
  
  
  METHODS
  A retrospective study was performed on 24 patients with AAD secondary to os odontoideum. All cases were with partial reduction after skeletal traction. Intraoperative open reduction and fixation were performed with a posterior screw-rod system, followed by interlaminae compression of an autologous iliac bone graft for fusion. The modified atlanto-dental interval (MADI) was measured to assess the degree of dislocation before traction, after traction, and postoperatively. Japanese Orthopaedic Association (JOA) score, Nurick scale score, visual analog scale score for neck pain (VASSNP), Neck Disability Index (NDI) score, and neck stiffness were used to evaluate functional outcomes.
  
  
  RESULTS
  The mean duration of follow-up was 43.0 ± 24.0 months. All patients achieved relief of symptoms and solid bone fusion. There were no complications associated with instrumentation and operation. At the final follow-up, the average MADI was reduced to 2.0 ± 0.8 mm (pretraction: 9.2 ± 1.1 mm; post-traction: 6.6 ± 0.7 mm; P < 0.001). The neck stiffness was significantly relieved (P < 0.001), and function of the spinal cord manifested by the JOA score and Nurick scale score significantly improved (all P < 0.001). The NDI score and VASSNP markedly decreased (all P < 0.001).
  
  
  CONCLUSIONS
  Intraoperative open reduction and interlaminae compression fusion using a posterior screw-rod system combined with a structural iliac bone graft is a safe and effective procedure for AAD secondary to os odontoideum.
authors.affiliation: Department of Orthopedics, Changzheng Hospital, The Second Military Medical University, Shanghai, People's Republic of China. Electronic address: nibin99@sohu.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: Lecheng
authors.initials: L
authors.lastname: Wu
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: 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: Fei
authors.initials: F
authors.lastname: Chen
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
mesh_terms: D000328:Adult; D001268:Atlanto-Axial Joint / Q000293:injuries* / Q000601:surgery; D016025:Bone Transplantation / Q000379:methods; D004548:Elasticity / Q000502:physiology; D005260:Female; D006801:Humans; D004204:Joint Dislocations / Q000209:etiology / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008297:Male; D009809:Odontoid Process / Q000002:abnormalities* / Q000601:surgery; D061646:Operative Time; D065289:Pedicle Screws; D012189:Retrospective Studies; D013123:Spinal Fusion / Q000379:methods*; D014057:Tomography, X-Ray Computed; D014143:Traction / Q000379:methods; D016896:Treatment Outcome
keywords: Atlantoaxial dislocation; Fixation; Fusion; Open reduction; Os odontoideum