title: Canine sacroiliac luxation: anatomic study of the craniocaudal articular surface angulation of the sacrum to define a safe corridor in the dorsal plane for placement of screws used for fixation in lag fashion.
abstract: OBJECTIVE
  To define a safe corridor in the dorsal plane relative to the articular surface for placement of a single screw in lag fashion to achieve stabilization of sacroiliac luxation in the dog.
  
  
  METHODS
  Cadaveric study.
  
  
  METHODS
  Dorsoventral radiographs of denuded canine sacra (n=49) were taken to determine the safe corridor in the craniocaudal plane, and the maximum, optimum and minimum angles were calculated that would allow a screw inserted in lag fashion to engage at least 60% of the width of the sacral body without cranial or caudal penetration through the bone.
  
  
  RESULTS
  The mean safe corridor in the dorsal plane is ∼24° wide. Mean craniocaudal minimum, optimum and maximum drill angles from the drill start point were 88°, 100°, and 111° from the articular surface, respectively. No single angle will completely avoid risk of screw penetration beyond the safe corridor cranially and caudally.
  
  
  CONCLUSIONS
  There is sufficient anatomic variation between different canine sacra that a single angle cannot be recommended for screw placement in the dorsal plane.
  
  
  CONCLUSIONS
  A standard angle cannot be recommended for screw placement in lag fashion within the canine sacrum in the dorsal plane. Because of the narrow width of the safe corridor, preoperative measurements on radiographs are recommended and a range of angled drill guides may be useful to decrease surgeon margin of error.
authors.affiliation: Department of Clinical Veterinary Studies, University of Bristol, Bristol, UK. k.bowlt@bristol.ac.uk
authors.forename: Kelly L
authors.initials: KL
authors.lastname: Bowlt
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Shales
mesh_terms: D000818:Animals; D001863:Bone Screws / Q000662:veterinary*; D002102:Cadaver; D004285:Dogs / Q000033:anatomy & histology*; D007593:Joint Instability / Q000601:surgery / Q000662:veterinary; D012446:Sacroiliac Joint / Q000033:anatomy & histology* / Q000601:surgery