title: C1-C2 intra-articular screw fixation for atlantoaxial posterior stabilization.
abstract: METHODS
  A trial of a new posterior stabilization technique for atlantoaxial instability and a report of preliminary results.
  
  
  OBJECTIVE
  To describe a new posterior stabilization technique for atlantoxial instability.
  
  
  BACKGROUND
  Magerl's transarticular screw fixation is an accepted technique for rigid atlantoaxial stabilization, which reportedly has yielded many good clinical results. However, the technique is technically demanding and poses a risk of injury to the nerves and veins.
  
  
  METHODS
  Eleven patients who had been treated with intra-articular screw fixation in combination with Halifax interlaminar clamp (OSTEONICS, Allendale, NJ) for atlantoaxial instability were observed. Results of their clinical examinations and biomechanical studies using resinous bones of a cervical spine model were reviewed.
  
  
  RESULTS
  In all patients, occipital pain, neck pain, and neural deficit improved, and bony fusion with no correction loss was shown on radiography. To date, no vascular or neural complications have been found, and no instrumentation failures have occurred. In the biomechanical study, the Halifax with transarticular screw fixation had significantly greater flexion stiffness than the Halifax only or the Halifax with intra-articular screw fixation, but the torsion stiffness of the Halifax with intra-articular screw fixation was significantly greater than that of the other Halifax combinations.
  
  
  CONCLUSIONS
  The preliminary results showed that this technique was effective in strengthening the rotational stability of the atlantoaxial fixation and was considered useful for atlantoaxial posterior stabilization.
authors.affiliation: Department of Orthopaedic Surgery, Nihon University School of Medicine, Tokyo, Japan. ytoku10@xd5.so-net.ne.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Tokuhashi
authors.forename: H
authors.initials: H
authors.lastname: Matsuzaki
authors.forename: Y
authors.initials: Y
authors.lastname: Shirasaki
authors.forename: T
authors.initials: T
authors.lastname: Tateishi
mesh_terms: D000328:Adult; D000368:Aged; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D001696:Biomechanical Phenomena; D001863:Bone Screws; D002574:Cervical Vertebrae; D005260:Female; D006801:Humans; D004204:Joint Dislocations / Q000601:surgery; D007593:Joint Instability / Q000601:surgery*; D008297:Male; D008722:Methods; D008875:Middle Aged; D011182:Postoperative Care; D011859:Radiography; D012399:Rotation