Alterations in trabecular bone microarchitecture in the ovine spine and distal femur following ovariectomy.
Osteoporosis is a bone disease resulting in increased fracture risk as a result of alterations in both quantity and quality of bone. Bone quality is a combination of metabolic and microarchitectural properties of bone that can help to explain the increased susceptibility to fracture. Translational animal models are essential to understanding the pathology and for evaluating potential treatments of this disease. Large animals, such as the ovariectomized sheep, have been used as models for post-menopausal osteoporosis. However, long-term studies have not been carried out to observe the effects of ovariectomy after more than one year. This study employed micro-computed tomography to quantify changes in microarchitectural and mechanical parameters in femoral condyles and vertebral bodies of sheep that were sacrificed one or two years following ovariectomy. In the vertebral body, microarchitectural characteristics were significantly degraded following one year of ovariectomy in comparison to controls. The mechanical anisotropy, determined from micro-scale finite element models, was also greater in the ovariectomized groups, although the fabric tensor anisotropy was similar. There was no greater architectural degradation following two years of ovariectomy compared to one. Ovariectomy had minimal effects on the trabecular architecture of the distal femur even after two years. These results indicate that the vertebral body is the preferred anatomic site for studying bone from the ovariectomized sheep model, and that architectural changes stabilize after the first year.
Tissue Mechanics Laboratory, Bioengineering Graduate Program, and Department of Aerospace and Mechanical Engineering, University of Notre Dame, 147 Multidisciplinary Research Building, Notre Dame, IN 46556, United States.
Tyler C
TC
Kreipke
Tissue Mechanics Laboratory, Bioengineering Graduate Program, and Department of Aerospace and Mechanical Engineering, University of Notre Dame, 147 Multidisciplinary Research Building, Notre Dame, IN 46556, United States.
Nicole C
NC
Rivera
Tissue Mechanics Laboratory, Bioengineering Graduate Program, and Department of Aerospace and Mechanical Engineering, University of Notre Dame, 147 Multidisciplinary Research Building, Notre Dame, IN 46556, United States.
Jacqueline G
JG
Garrison
Surgical Research Laboratory, Department of Clinical Sciences, Colorado State University, Ft. Collins, CO, United States.
Jeremiah T
JT
Easley
Surgical Research Laboratory, Department of Clinical Sciences, Colorado State University, Ft. Collins, CO, United States.
A Simon
AS
Turner
Tissue Mechanics Laboratory, Bioengineering Graduate Program, and Department of Aerospace and Mechanical Engineering, University of Notre Dame, 147 Multidisciplinary Research Building, Notre Dame, IN 46556, United States. Electronic address: gniebur@nd.edu.
Glen L
GL
Niebur
D000818:Animals; D016880:Anisotropy; D015519:Bone Density; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging*; D050723:Fractures, Bone / Q000000981:diagnostic imaging; D008137:Longitudinal Studies; D023421:Models, Animal; D010024:Osteoporosis / Q000000981:diagnostic imaging*; D010052:Ovariectomy; D012756:Sheep; D034561:Sheep, Domestic; D013131:Spine / Q000000981:diagnostic imaging*; D013314:Stress, Mechanical; D014057:Tomography, X-Ray Computed
Femur; Microarchitecture; Osteoporosis; Ovariectomy; Sheep; Vertebrae