title: Bilateral atlas laminar hook combined with transarticular screw fixation for an unstable bursting atlantal fracture.
abstract: BACKGROUND
  The unstable atlas burst fracture ("Jefferson fracture") is a fracture of the anterior and posterior atlantal arch with rupture of the transverse atlantal ligament and an incongruence of the atlanto-occipital and the atlanto-axial joint facets. The posterior atlantoaxial fusion is frequently used to reconstruct the stability of atlantoaxial joint. Conventional posterior atlantoaxial fixations are associated with high rates of pseudoarthrosis and chronic atlantoaxial instability. As a modified three-point fixation the bilateral C1-2 transarticular screws combined with C1 laminar hook and bone grafts can provide best biomechanical stability, but no standard protocol has been reported for the use of this fusion technique. A retrospective review of clinical series should be conducted to evaluate the clinical outcome of bilateral atlas laminar hook combined with transarticular screw fixation for unstable bursting atlantal fracture.
  
  
  METHODS
  From March 2002 to March 2006, there were total 12 cases of unstable atlantal bursting fractures, 10 males and 2 females, age ranging 18-54, with mean of 36 years old. All patients were operated on posterior atlantoaxial fusion using bilateral atlas laminar hook combined with transarticular screw fixation after atlantoaxial joint were reduced and followed up for 12-24 months. The medical records and radiographs of the 12 patients were reviewed. Each patient underwent a complete cervical radiograph series including lateral flexion-extension view and a computed topographic scan. The Frankel grades and ASIA scores were applied to assess the neurologic status.
  
  
  RESULTS
  In all patients, a good bony fusion of the atlanto-axial segment was achieved. All patients showed significant improvement of the neurologic defect and no instability on their follow-up plain radiographs and computerized tomography in follow-up interval.
  
  
  CONCLUSIONS
  For the patients who suffer from the unstable bursting atlantal fracture, the nonoperative methods could carry some clinical complications including infection, nerve injury, etc. and is frequently failure, Posterior atlantoaxial fusion using bilateral atlas laminar hook combined with transarticular screw fixation is an effective treatment.
authors.affiliation: Department of Orthopaedics, Changzheng Hospital, 415 Fengyang Road, Huangpu District, Shanghai, People's Republic of China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Guo
authors.forename: Bin
authors.initials: B
authors.lastname: Ni
authors.forename: Mingfei
authors.initials: M
authors.lastname: Wang
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Songkai
authors.initials: S
authors.lastname: Li
authors.forename: Fengjin
authors.initials: F
authors.lastname: Zhou
mesh_terms: D000293:Adolescent; D000328:Adult; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D001863:Bone Screws; D001270:Cervical Atlas / Q000293:injuries*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000601:surgery; D008023:Ligaments, Articular / Q000293:injuries* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D011859:Radiography; D016103:Spinal Fractures / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery*; D013123:Spinal Fusion / Q000379:methods*; D015898:Tomography Scanners, X-Ray Computed; D016896:Treatment Outcome; D055815:Young Adult