title: [Instability of C1,2 treated with transcutaneous anterior lateral mass fixation and bone grafting].
abstract: OBJECTIVE
  Creating the method of transcutaneous anterior lateral mass fixation for instability of C(1,2).
  
  
  METHODS
  The regular and safe angle and the distance between the median margin of vertebral artery and median line of superior and inferior margin of axis were measured with computerized tomography. Fifteen cases of C(1,2) instability including 7 cases atlanto-axial dislocation, 3 cases of Jefferson's fracture, 1 case of dental fracture and dislocation and 4 cases of fractures of anterior arch of C1 were treated with pertacuneous anterior lateral mass screws and bone grafting with new-designed hole instrumentations according to the measurement of 40 normal atlanto-axial vertebrae.
  
  
  RESULTS
  In posterior-anterior ray the regular angle was 24.0 degrees +/- 3.7 degrees (right side), and 23.8 degrees +/- 1.8 degrees (left side); safe angle is 15.2 degrees - 30.3 degrees (left side) and 14.8 degrees - 32.1 degrees (right side), respectively. The distance between the median margin of vertebral artery and median line of superior and inferior margin of vertebral artery and median line of superior and inferior margin of lateral mass was (5.6 +/- 2.2) mm (right) and (5.8 +/- 1.9) mm (left). In lateral ray the regular angle was 24.1 degrees +/- 1.8 degrees, and safe angle 12.6 degrees - 26.8 degrees. All cases reach a satisfactory result of fixation without the injury of vertebral artery, spinal cord and esophagus. The acupuncture point recovers without infection.
  
  
  CONCLUSIONS
  This operation procedure for instability of C(1,2) has the advantage of less trauma and bleeding, simply operation and bone grafting at the same time. The operation procedure is safe with reasonable instrument and selecting the correct puncture point, angle and depth.
authors.affiliation: Department of Orthopedics, the Second Affiliated Hospital of Wenzhou Medical College, Wenzhou 325003, China.
authors.forename: Yong-long
authors.initials: YL
authors.lastname: Chi
authors.forename: Hua-zi
authors.initials: HZ
authors.lastname: Xu
authors.forename: Yan
authors.initials: Y
authors.lastname: Lin
authors.forename: Qi-shan
authors.initials: QS
authors.lastname: Huang
authors.forename: Fang-min
authors.initials: FM
authors.lastname: Mao
authors.forename: Xiang-yang
authors.initials: XY
authors.lastname: Wang
authors.forename: Lei
authors.initials: L
authors.lastname: Yang
mesh_terms: D000328:Adult; D000368:Aged; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D001863:Bone Screws; D016025:Bone Transplantation; D002574:Cervical Vertebrae / Q000293:injuries; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000209:etiology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D013123:Spinal Fusion / Q000379:methods*; D013124:Spinal Injuries / Q000150:complications