title: Posterior C1-C2 fusion using C1 lateral mass and C2 pars screw with rod fixation: techniques and outcomes.
abstract: OBJECTIVE
  The atlantoaxial instability often requires posterior fixation surgery. Multiple techniques have been described for C1-C2 fixation. Transarticular atlantoaxial screw has been demonstrated to be effective for C1-C2 stabilization. However, up to 20% of patients are not candidates for the procedure. New technique concerning the placement of individual screws in CI lateral mass and C2 pars screw with additional rods for their connection was described, either as a salvage method for unsuccessful C1-C2 stabilization or as an effective alternative technique. The authors presented their experience using C1 lateral mass and C2 pars screws with rod fixation for C1-C2 stabilization.
  
  
  METHODS
  Between May 2007 and October 2008, 10 patients (7 male, 3 female) whose age ranged from 15 to 59 years-old underwent posterior fixation using C1 lateral mass and C2 pars screw with rod fixation. Six patients had atlantoaxial subluxation due to os odontoideum, two patients had chronic C1-C2 subluxation, and two patients had acute CI-C2 subluxation from a motor vehicle accident. All screws were placed under lateral fluoroscopic guidance.
  
  
  RESULTS
  C1 lateral mass and C2 pars screw with rod fixation were used to achieve C1-C2 stabilization in all patients. All screws were positioned correctly in both C1 and C2. There were no permanent complications. In all cases, rigid fixation was confirmed on postoperative radiographs and maintained on follow-up radiographs.
  
  
  CONCLUSIONS
  The lateral mass and C2 pars screw with rod fixation is an effective method of stabilizing the atlantoaxial complex. This procedure provides rigid fixation with relative safety.
authors.affiliation: Department of Neurosurgery, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand. a_nitising@yahoo.com
authors.forename: Akkapong
authors.initials: A
authors.lastname: Nitising
authors.forename: Chumpol
authors.initials: C
authors.lastname: Jetjumnong
authors.forename: Nanthasak
authors.initials: N
authors.lastname: Tisavipat
authors.forename: Sarun
authors.initials: S
authors.lastname: Nantaaree
mesh_terms: D000293:Adolescent; D000328:Adult; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D001858:Bone Nails; D001863:Bone Screws; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery*; D005260:Female; D005471:Fluoroscopy; D005593:Fracture Fixation, Internal / Q000379:methods; D006801:Humans; D016268:Internal Fixators; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D013123:Spinal Fusion / Q000295:instrumentation / Q000379:methods*; D016896:Treatment Outcome; D055815:Young Adult