title: Effect of differences in tendon properties on functionality of the passive stay apparatus in horses.
abstract: OBJECTIVE
  To determine the effect of differences in structural and mechanical tendon properties on functionality of the passive stay apparatus in horses.
  
  
  METHODS
  5 forelimbs each from nondwarf Friesians, dwarf Friesians, and ponies.
  
  
  METHODS
  Harvested forelimbs were loaded to test the passive stay apparatus. Tendons that stabilize the distal portion of the limb (superficial digital flexor tendon, deep digital flexor tendon, and tendo interosseus [suspensory ligament]) were isolated, and force-elongation data were obtained. Bone lengths, initial tendon lengths, and initial tendon cross-sectional areas were measured, and Young moduli were calculated. A model was used to determine whether joint angles could be explained by these 4 factors only.
  
  
  RESULTS
  Dwarf limbs were unable to stand passively under loading because tendons that prevent overextension of the distal limb joints were too long and compliant to prevent over-extension. Tendon properties of limbs of nondwarf Friesians appeared to be intermediate between those of ponies and dwarf Friesians.
  
  
  CONCLUSIONS
  Dysfunction of the passive stay apparatus in dwarf Friesians could be related to differences in structural and material properties of the tendons that result in hyperextension of the joints under loading. Nondwarf Friesians had intermediate tendon properties, which might be a breed-specific variation. Results indicated that certain tendon properties were associated with load failure of the stay apparatus and provided additional information about the functionality and requirements of the passive stay apparatus.
authors: Experimental Zoology Group, Wageningen Institute of Animal Sciences, Wageningen University, 6709 PG Wageningen, The Netherlands. Sander.Gussekloo@wur.nl
authors: Sander W S
authors: SW
authors: Gussekloo
authors: Jerta
authors: J
authors: Lankester
authors: Wim
authors: W
authors: Kersten
authors: Willem
authors: W
authors: Back
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001947:Breeding; D055119:Elastic Modulus; D005552:Forelimb / Q000033:anatomy & histology / Q000502:physiology; D006736:Horses / Q000033:anatomy & histology* / Q000502:physiology; D007596:Joints / Q000033:anatomy & histology / Q000502:physiology; D008023:Ligaments, Articular / Q000033:anatomy & histology / Q000502:physiology; D013710:Tendons / Q000033:anatomy & histology* / Q000502:physiology