Determination of the stiffness of the equine spine.
BACKGROUND
Mechanical properties of the equine back are the bases for realistic modelling of the back, which is recognised as an important step towards improved understanding of the pathogenesis of equine back conditions.


OBJECTIVE
The stiffness of the equine back depends on the direction of the applied force and on the position of the spine.


METHODS
Fourteen dissected spines were tested in a tensile testing machine. In 3 different positions, simulating dorsoventral, laterolateral and dorsoventral-30 degree rotated movement, force was applied on the dorsal spinous process of T12 to reach an excursion of 4 cm in each direction. The normal distribution of the stiffness coefficients was tested with a Kolmogorov-Smirnov test and the stiffness coefficients were compared with paired t tests.


RESULTS
Mean +/- s.d. dorsoventral stiffness was 2093 +/- 611 N/m for the nonrotated spine and 2182 +/- 459 N/m for the 30 degree rotated spine. Mean laterolateral stiffness was significantly lower than dorsoventral stiffness at 1454 +/- 156 N/m.


CONCLUSIONS
The stiffness of the spine depends on the direction of loading.


CONCLUSIONS
The stiffness of the spine under loading may be a relevant factor in the development of back disorders.
Schlacher
C
C
Department V, Clinic of Orthopaedics in Ungulates, University of Veterinary Medicine, Vienna, Austria.
Peham
C
C
Licka
T
T
Schobesberger
H
H
D000818:Animals; D001696:Biomechanical Phenomena; D006734:Horse Diseases / Q000209:etiology / Q000517:prevention & control; D006736:Horses / Q000033:anatomy & histology / Q000502:physiology*; D066298:In Vitro Techniques; D008159:Lumbar Vertebrae / Q000502:physiology; D013122:Spinal Diseases / Q000209:etiology / Q000517:prevention & control / Q000662:veterinary; D013131:Spine / Q000033:anatomy & histology / Q000502:physiology*; D013314:Stress, Mechanical; D016474:Weight-Bearing