| Records |
| Author |
Skedros, J.G.; Dayton, M.R.; Sybrowsky, C.L.; Bloebaum, R.D.; Bachus, K.N. |
| Title |
The influence of collagen fiber orientation and other histocompositional characteristics on the mechanical properties of equine cortical bone |
Type |
Journal Article |
| Year |
2006 |
Publication |
The Journal of Experimental Biology |
Abbreviated Journal |
J Exp Biol |
| Volume |
209 |
Issue |
Pt 15 |
Pages |
3025-3042 |
| Keywords |
Animals; Biomechanics; Bone and Bones/*physiology; Collagen/*physiology; Forelimb; Horses/*physiology |
| Abstract |
This study examined relative influences of predominant collagen fiber orientation (CFO), mineralization (% ash), and other microstructural characteristics on the mechanical properties of equine cortical bone. Using strain-mode-specific (S-M-S) testing (compression testing of bone habitually loaded in compression; tension testing of bone habitually loaded in tension), the relative mechanical importance of CFO and other material characteristics were examined in equine third metacarpals (MC3s). This model was chosen since it had a consistent non-uniform strain distribution estimated by finite element analysis (FEA) near mid-diaphysis of a thoroughbred horse, net tension in the dorsal/lateral cortices and net compression in the palmar/medial cortices. Bone specimens from regions habitually loaded in tension or compression were: (1) tested to failure in both axial compression and tension in order to contrast S-M-S vs non-S-M-S behavior, and (2) analyzed for CFO, % ash, porosity, fractional area of secondary osteonal bone, osteon cross-sectional area, and population densities of secondary osteons and osteocyte lacunae. Multivariate multiple regression analyses revealed that in S-M-S compression testing, CFO most strongly influenced total energy (pre-yield elastic energy plus post-yield plastic energy); in S-M-S tension testing CFO most strongly influenced post-yield energy and total energy. CFO was less important in explaining S-M-S elastic modulus, and yield and ultimate stress. Therefore, in S-M-S loading CFO appears to be important in influencing energy absorption, whereas the other characteristics have a more dominant influence in elastic modulus, pre-yield behavior and strength. These data generally support the hypothesis that differentially affecting S-M-S energy absorption may be an important consequence of regional histocompositional heterogeneity in the equine MC3. Data inconsistent with the hypothesis, including the lack of highly longitudinal collagen in the dorsal-lateral ;tension' region, paradoxical histologic organization in some locations, and lack of significantly improved S-M-S properties in some locations, might reflect the absence of a similar habitual strain distribution in all bones. An alternative strain distribution based on in vivo strain measurements, without FEA, on non-Thoroughbreds showing net compression along the dorsal-palmar axis might be more characteristic of the habitual loading of some of the bones that we examined. In turn, some inconsistencies might also reflect the complex torsion/bending loading regime that the MC3 sustains when the animal undergoes a variety of gaits and activities, which may be representative of only a portion of our animals, again reflecting the possibility that not all of the bones examined had similar habitual loading histories. |
Address  |
Utah Bone and Joint Center, 5323 S. Woodrow Street #202, Salt Lake City, UT 84107, USA. jskedros@utahboneandjoint.com |
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English |
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0022-0949 |
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| Notes |
PMID:16857886 |
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no |
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Serial |
1868 |
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| Author |
Clayton, H.M. |
| Title |
Comparison of the stride kinematics of the collected, working, medium and extended trot in horses |
Type |
Journal Article |
| Year |
1994 |
Publication |
Equine Veterinary Journal |
Abbreviated Journal |
Equine Vet J |
| Volume |
26 |
Issue |
3 |
Pages |
230-234 |
| Keywords |
Analysis of Variance; Animals; Biomechanics; Female; Forelimb/anatomy & histology/physiology; Gait/*physiology; Hindlimb/anatomy & histology/physiology; Horses/anatomy & histology/*physiology; Locomotion/physiology; Male; Motion Pictures |
| Abstract |
Highly-trained dressage horses were studied to test the hypothesis that stride length is altered independently of stride duration in the transitions between the collected, working, medium and extended trot. Six well-trained dressage horses were filmed at a frame rate of 150 frames/s performing the collected, working, medium and extended trots in a sand arena. Temporal, linear and angular data were extracted from the films, with 4 strides being analysed for each horse and gait type. There were no significant asymmetries between the left and rights limbs or diagonals when data from the whole group were pooled, but 3 horses showed asymmetries in one or more variables (P < 0.01). Analysis of variance and post-hoc tests indicated that the speed increased significantly (P < 0.01) from the collected (3.20 m/s) to the working (3.61 m/s) to the medium (4.47 m/s) to the extended (4.93 m/s) trot. The increases in speed were associated with a significant increase in stride length from 250 cm in the collected trot, to 273 cm in the working trot, 326 cm in the medium trot and 355 cm in the extended trot (P < 0.01). The lengthening of the stride was a result of increases between each gait type in the over-reach distance, whereas the diagonal distance was significantly longer in the extended than the collected trot only (P < 0.01). The stride duration tended to decrease as speed increased, and the difference became significant between the collected and extended trots (P < 0.01). |
| Address |
Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada |
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English |
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0425-1644 |
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| Notes |
PMID:8542844 |
Approved |
no |
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Equine Behaviour @ team @ |
Serial |
3746 |
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| Author |
Argue, C.K.; Clayton, H.M. |
| Title |
A preliminary study of transitions between the walk and trot in dressage horses |
Type |
Journal Article |
| Year |
1993 |
Publication |
Acta Anatomica |
Abbreviated Journal |
Acta Anat (Basel) |
| Volume |
146 |
Issue |
2-3 |
Pages |
179-182 |
| Keywords |
Animals; Forelimb/physiology; Gait/*physiology; Hindlimb/physiology; Horses/*physiology; Locomotion/physiology; *Physical Conditioning, Animal |
| Abstract |
The object of this study was to determine the limb support sequence during the transitions from walk to trot and from trot to walk in dressage horses under saddle and to test the null hypothesis that the limb support sequence during the transitions is not related to the level of training. Sixteen dressage horses training at novice to FEI Grand Prix level were videotaped performing an average of 9 transitions each from walk to trot and from trot to walk. The 30-Hz videotapes were viewed in slow motion, and based on the limb support sequence the transitions were categorized into two types. In type 1 transitions there were no intermediate steps between the walk and trot sequences. Type 2 transitions were characterized by intermediate steps, including a single support phase. The Kendall rank-order correlation coefficient showed that a higher level of training was positively associated with an increased percentage of type 1 transitions for both walk-to-trot transitions (p < or = 0.05) and trot-to-walk transitions (p < or = 0.01). No significant preference for initiating or completing the trot on the left or right diagonal was found using the binomial test for individual horses and the Wilcoxon signed-ranks test for the group. |
| Address |
Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada |
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English |
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Abbreviated Series Title |
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Edition |
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0001-5180 |
ISBN |
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| Notes |
PMID:8470463 |
Approved |
no |
| Call Number |
Equine Behaviour @ team @ |
Serial |
3752 |
| Permanent link to this record |
