title: Comparative anatomy and biomechanical properties of atlantoaxial ligaments in equine, bovine, and canine cadaveric specimens.
abstract: OBJECTIVE
  Atlantoaxial instability has been reported in humans, dogs, equids and ruminants. The functional role of the atlantoaxial ligaments has only been described rudimentarily in equids and ruminants. The goal of the present cadaveric study was to compare the anatomy between the different species and to comparatively assess the role of the stabilizing ligaments of the atlantoaxial joint under sagittal shear loading in canine, equine, and bovine cervical spines.
  
  
  METHODS
  Three equine, bovine, and canine cadaveric specimens were investigated. Biomechanical testing was performed using a purpose built shear-testing device driven by a uniaxial servo-hydraulic testing machine. Three cycles in a dorsoventral direction with a constant quasi-static velocity of 0.2 mm/s up to a limiting force of 50 N (canine) or 250 N (bovine, equine), respectively, were performed for each specimen tested. Load and linear displacement were measured by the displacement sensor and load cell of the testing system at a sampling rate of 20 Hz. Tests were performed and the range of motion determined with both intact and transected atlantoaxial ligaments.
  
  
  RESULTS
  The range of motion was significantly increased after transection of the ligaments only in the canine specimens. The bovine atlantoaxial joint was biomechanically more stable than in equids.
  
  
  CONCLUSIONS
  Species-specific anatomical and biomechanical differences of the atlantoaxial ligaments in canines, equids, and bovines were detected. The significance of these differences and their impact on the pathogenesis of atlantoaxial subluxations and subsequent treatment remain open questions.
authors.affiliation: Prof. Franck Forterre, DVM, DECVS, Department of Clinical Veterinary Medicine, Small Animal Surgery, Vetsuisse Faculty, University of Bern, Länggassstrasse 128, 3012 Bern, Switzerland, Phone: +41 31 6312401, Fax: +41 31 6312275, E-mail: franck.forterre@vetsuisse.unibe.ch.
authors.forename: Franck
authors.initials: F
authors.lastname: Forterre
authors.forename: Michael H
authors.initials: MH
authors.lastname: Stoffel
authors.forename: Christoph
authors.initials: C
authors.lastname: Koch
authors.forename: Christina
authors.initials: C
authors.lastname: Precht
authors.forename: Maja
authors.initials: M
authors.lastname: Waschk
authors.forename: Alexander
authors.initials: A
authors.lastname: Bürki
mesh_terms: D000717:Anatomy, Comparative; D000818:Animals; D001268:Atlanto-Axial Joint / Q000033:anatomy & histology*; D001696:Biomechanical Phenomena / Q000502:physiology*; D002102:Cadaver; D002417:Cattle / Q000033:anatomy & histology; D004285:Dogs / Q000033:anatomy & histology; D006736:Horses / Q000033:anatomy & histology; D006801:Humans; D007593:Joint Instability; D008022:Ligaments; D016059:Range of Motion, Articular
keywords: Atlantoaxial ligaments; biomechanical properties; cow; dog; horse