title: CT scan based determination of optimal bone corridor for atlantoaxial ventral screw fixation in miniature breed dogs.
abstract: OBJECTIVE
  To describe the most reliable insertion angle, corridor length and width to place a ventral transarticular atlantoaxial screw in miniature breed dogs.
  
  
  METHODS
  Retrospective CT imaging study.
  
  
  METHODS
  Cervical CT scans of toy breed dogs (n = 21).
  
  
  METHODS
  Dogs were divided into 2 groups--group 1: no atlantoaxial abnormalities; group 2: atlantoaxial instability. Insertion angle in medial to lateral and ventral to dorsal direction was measured in group 1. Corridor length and width were measured in groups 1 and 2. Corridor width was measured at 3 points of the corridor. Each variable was measured 3 times and the mean used for statistical analysis.
  
  
  RESULTS
  Mean ± SD optimal transarticular atlantoaxial insertion angle was determined to be 40 ± 1° in medial to lateral direction from the midline and 20 ± 1° in ventral to dorsal direction from the floor of the neural canal of C2. Mean corridor length was 7 mm (range, 4.5-8.0 mm). Significant correlation was found between corridor length, body weight, and age. Mean bone corridor width ranged from 3 to 5 mm. Statistically significant differences were found between individuals, gender and measured side.
  
  
  CONCLUSIONS
  Optimal placement of a transarticular screw for atlantoaxial joint stabilization is very demanding because the screw path corridor is very narrow.
authors.affiliation: Small Animal Clinic, Department of Surgery and Radiology, University of Berne, Berne, Switzerland.
authors.forename: Núria
authors.initials: N
authors.lastname: Vizcaíno Revés
authors.forename: Cristina
authors.initials: C
authors.lastname: Stahl
authors.forename: Michael
authors.initials: M
authors.lastname: Stoffel
authors.forename: Monty
authors.initials: M
authors.lastname: Bali
authors.forename: Franck
authors.initials: F
authors.lastname: Forterre
mesh_terms: D000818:Animals; D001174:Arthrodesis / Q000662:veterinary*; D001268:Atlanto-Axial Joint / Q000033:anatomy & histology / Q000601:surgery*; D001863:Bone Screws / Q000662:veterinary*; D004285:Dogs; D014057:Tomography, X-Ray Computed / Q000662:veterinary*