title: Transarticular screw and C1 hook fixation for os odontoideum with atlantoaxial dislocation.
abstract: OBJECTIVE
  To introduce a fixation device composed of C1-2 transarticular (TA) screws and C1 hooks and explore its indication and clinical outcome for os odontoideum with atlantoaxial dislocation (AAD).
  
  
  METHODS
  From January 2004 to December 2008, 12 patients with os odontoideum (5 men and 7 women, average age 37.7 years [range 14-62 years]) were treated in the authors' hospital. All patients had AAD with local symptoms, and 10 had myelopathy. All patients underwent a posterior atlantoaxial fixation with C1-2 TA screws and C1 hooks. Clinical and radiographic analyses were performed at 3, 6, and 12 months postoperatively and annually thereafter.
  
  
  RESULTS
  The follow-up period was 12-66 months (average follow-up period 35.5 months). No neurologic or vascular complications occurred in these cases, and the device was placed well with no loosening or breakage. Plain radiographs and three-dimensional reconstruction of computed tomography (CT) images revealed solid bony fusion with a good alignment of C1 and C2 at 3 months postoperatively. No hardware failure, pseudarthrosis, or instability was noted during the follow-up period. All patients had relief of pain within 3 months, and neurologic symptoms were substantially improved.
  
  
  CONCLUSIONS
  When appropriate patients are selected, C1-2 TA screws combined with C1 hooks can be used to treat os odontoideum with AAD effectively with a relatively simple procedure resulting in excellent biomechanical strength and high bone fusion rate. Preoperative planning is crucial for the management of os odontoideum with AAD.
authors: Spine Center, Department of Orthopaedics, Changzheng Hospital, Second Military Medical University, Shanghai, China. nibin99@sohu.com
authors: Bin
authors: B
authors: Ni
authors: Fengjin
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authors: Zhou
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