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Effect of age on bone mineral density and micro architecture in the radius and tibia of horses: an Xtreme computed tomographic study.

Fürst A, Meier D, Michel S, Schmidlin A, Held L, Laib A - BMC Vet. Res. (2008)

Bottom Line: However, the microarchitecture varied with the age of the horse; the number of trabeculae decreased significantly and the distance between trabeculae increased significantly with increasing age.There were no significant differences between bones of the left and right limbs or between the radius and tibia.The variables investigated did not differ between geldings and mares.

View Article: PubMed Central - HTML - PubMed

Affiliation: Equine Hospital, Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland. Afuerst@vetclinics.uzh.ch

ABSTRACT

Background: The effect of age on the bone mineral density and microarchitecture of the equine radius and tibia was investigated. Fifty-six bones from 15 horses aged four to 21 years were used. There were nine geldings and six mares, and none of the horses had any disease influencing bone properties. Xtreme computed tomography was used to evaluate a 9-mm segment of the diaphysis and metaphysis of each bone. The following variables were determined: length of the bone, circumference and diameter in the frontal and sagittal planes in the middle of the bone.Diaphysis: total volume, bone volume, bone volume ratio, slice area, bone area, marrow area, cortical and marrow thickness, bone mineral density, polar moment of inertia of the cortex.Metaphysis: total area, bone area, cortical bone area, cortical thickness, bone mineral density, bone mineral density in the cortex, bone mineral density in the trabecular region, trabecular number, trabecular thickness, trabecular separation, polar moment of inertia of the metaphysis, polar moment of inertia of the cortex of the metaphysis.

Results: Bone density and microarchitecture were not affected by breed or gender. However, the microarchitecture varied with the age of the horse; the number of trabeculae decreased significantly and the distance between trabeculae increased significantly with increasing age. There were no significant differences between bones of the left and right limbs or between the radius and tibia.

Conclusion: The variables investigated did not differ between geldings and mares. However, there were age-related changes in the microstructure of the bones. Further experimental studies are necessary to determine whether these changes reduce bone strength. Age-related changes in the bones were seen and may explain the higher incidence of fractures and fissures in older horses.

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Radius with a small number of trabeculae.
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Figure 6: Radius with a small number of trabeculae.

Mentions: With respect to the effect of age on bone quality, the trabecular number (Fig. 3 and 4) and trabecular BMD (Fig. 5) decreased, and the trabecular separation and cortical BMD of the metaphysis increased in the radius and tibia with increasing age. Based on these findings, we assume that the bone trabeculae are not replaced but rather progressively decrease in number with age. The trabecular thickness and volume also tended to decrease, although the changes were not significant. Evaluation of a larger number of bones may yield more age-related variables. Evaluation of the polar moment of inertia of the diaphysis and metaphysis of the radius and tibia revealed no age-related changes. Although in one study, horses with fractures were older than the overall equine patient population [42], there are no more indications that older horses have a higher incidence of fractures than younger horses. There is no scientific evidence of age-related osteoporosis in horses. Osteoporosis is defined as a severe loss in BMD predisposing the individual to spontaneous fractures [43]. Osteopenia, on the other hand, describes a decrease in BMD that is not associated with spontaneous fractures [44]. According to these definitions, the changes in trabecular BMD, number and separation that we observed in the older horses do not constitute osteoporosis (Fig. 6 and 7). Because of this, osteopenia commonly goes unnoticed and is probably more common than osteoporosis. However, other studies involving mostly cannon bones suggest that a decrease in the number and thickness of the trabeculae increases the risk of fracture [38-40]. Several studies have evaluated the mechanical properties of bone using micro-computed tomography and related these properties to bone strength [33,45-47]. Nevertheless, because they have been used with success in elderly people, locking compression plates, which increase the stability of fracture repair, might be advantageous in horses as well [48].


Effect of age on bone mineral density and micro architecture in the radius and tibia of horses: an Xtreme computed tomographic study.

Fürst A, Meier D, Michel S, Schmidlin A, Held L, Laib A - BMC Vet. Res. (2008)

Radius with a small number of trabeculae.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2267174&req=5

Figure 6: Radius with a small number of trabeculae.
Mentions: With respect to the effect of age on bone quality, the trabecular number (Fig. 3 and 4) and trabecular BMD (Fig. 5) decreased, and the trabecular separation and cortical BMD of the metaphysis increased in the radius and tibia with increasing age. Based on these findings, we assume that the bone trabeculae are not replaced but rather progressively decrease in number with age. The trabecular thickness and volume also tended to decrease, although the changes were not significant. Evaluation of a larger number of bones may yield more age-related variables. Evaluation of the polar moment of inertia of the diaphysis and metaphysis of the radius and tibia revealed no age-related changes. Although in one study, horses with fractures were older than the overall equine patient population [42], there are no more indications that older horses have a higher incidence of fractures than younger horses. There is no scientific evidence of age-related osteoporosis in horses. Osteoporosis is defined as a severe loss in BMD predisposing the individual to spontaneous fractures [43]. Osteopenia, on the other hand, describes a decrease in BMD that is not associated with spontaneous fractures [44]. According to these definitions, the changes in trabecular BMD, number and separation that we observed in the older horses do not constitute osteoporosis (Fig. 6 and 7). Because of this, osteopenia commonly goes unnoticed and is probably more common than osteoporosis. However, other studies involving mostly cannon bones suggest that a decrease in the number and thickness of the trabeculae increases the risk of fracture [38-40]. Several studies have evaluated the mechanical properties of bone using micro-computed tomography and related these properties to bone strength [33,45-47]. Nevertheless, because they have been used with success in elderly people, locking compression plates, which increase the stability of fracture repair, might be advantageous in horses as well [48].

Bottom Line: However, the microarchitecture varied with the age of the horse; the number of trabeculae decreased significantly and the distance between trabeculae increased significantly with increasing age.There were no significant differences between bones of the left and right limbs or between the radius and tibia.The variables investigated did not differ between geldings and mares.

View Article: PubMed Central - HTML - PubMed

Affiliation: Equine Hospital, Vetsuisse Faculty, University of Zurich, 8057 Zurich, Switzerland. Afuerst@vetclinics.uzh.ch

ABSTRACT

Background: The effect of age on the bone mineral density and microarchitecture of the equine radius and tibia was investigated. Fifty-six bones from 15 horses aged four to 21 years were used. There were nine geldings and six mares, and none of the horses had any disease influencing bone properties. Xtreme computed tomography was used to evaluate a 9-mm segment of the diaphysis and metaphysis of each bone. The following variables were determined: length of the bone, circumference and diameter in the frontal and sagittal planes in the middle of the bone.Diaphysis: total volume, bone volume, bone volume ratio, slice area, bone area, marrow area, cortical and marrow thickness, bone mineral density, polar moment of inertia of the cortex.Metaphysis: total area, bone area, cortical bone area, cortical thickness, bone mineral density, bone mineral density in the cortex, bone mineral density in the trabecular region, trabecular number, trabecular thickness, trabecular separation, polar moment of inertia of the metaphysis, polar moment of inertia of the cortex of the metaphysis.

Results: Bone density and microarchitecture were not affected by breed or gender. However, the microarchitecture varied with the age of the horse; the number of trabeculae decreased significantly and the distance between trabeculae increased significantly with increasing age. There were no significant differences between bones of the left and right limbs or between the radius and tibia.

Conclusion: The variables investigated did not differ between geldings and mares. However, there were age-related changes in the microstructure of the bones. Further experimental studies are necessary to determine whether these changes reduce bone strength. Age-related changes in the bones were seen and may explain the higher incidence of fractures and fissures in older horses.

Show MeSH
Related in: MedlinePlus