Modeling the Long Term Effects of Alendronate on Bone Mass Preservation of the Femur with Articular Surface and Total Hip Replacements

Hryce, Trevor J

doi:10.15368/theses.2010.47

Cited by 4 publications

(4 citation statements)

References 61 publications

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“…A bone UMAT which would accept user defined input variables had already been created (Hryce, 2010). The UMAT was able to accept a text file containing the initial porosity data which would then be applied to the FE model in ABAQUS.…”

Section: Pre-condition Data Applicationmentioning

confidence: 99%

Development of a Subject Specific Finite Element Model Used to Predict the Effects of a Single Leg Extension Exercise

Gleeson¹

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The study presented attempts to prove the concept that mechanical changes in the structure of a bone can be predicted for a specific exercise by a subject specific model created from CT data, MRI data, EMG data, and a physiologic FE model. Previous work generated a subject specific FE model of a femur via CT and MRI data as well as created a set of subject specific biomechanical muscle forces that are required to perform a single leg extension exercise. The FE model and muscle forces were implemented into a single leg extension FE code (ABAQUS) along with a specialized bone remodeling UMAT. The UMAT updated the mechanical properties of the femur via a damage-repair bone remodeling algorithm. The single leg extension FE code was verified by applying walking loads to the femur and allowing the system to equilibrate. The results were used to apply the appropriate walking loads to the final FE simulation for the single leg extension exercise. The final FE simulation included applying the single leg extension loads over a one year period and plotting the change in porosity at various regions of the femoral neck. Although only two regions were found to generate valid results, the data seemed counterintuitive to Wolff's Law which states that bone adaptation is promoted when the material is stressed. The model was successful in creating a subject specific model that is capable of predicting changes in the mechanical properties of bone. However, in order to generate valid FE model results, further understanding of the bone remodeling process and application via a FE model is required.

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Section: Pre-condition Data Applicationmentioning

confidence: 99%

Development of a Subject Specific Finite Element Model Used to Predict the Effects of a Single Leg Extension Exercise

Gleeson¹

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“…Once the cells are differentiated, the osteoblasts form new bone which is a much slower process than resorption [12]. The time for each stage differs: resorption lasts about 3 weeks, formation lasts about 3 months, and the total remodeling process takes about 4 months [12,18]. A sketch of an osteonal BMU can be seen in Figure 12, which displays the stages of resorption, reversal, and refilling.…”

Section: Remodeling Cyclementioning

confidence: 99%

Effects of Ovariectomy and Anatomical Location on Osteonal Encroachment in Adult Cortical Ovine Bone

Ryan¹

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The purpose of this study is to further quantify adult ovine ovariectomized bone for new remodeling characteristics to obtain a better understanding of how remodeling is occurring and the effectiveness of this animal model for the study of postmenopausal osteoporosis.Postmenopausal osteoporosis is a major health concern and animal models to test new treatment options are needed. The ovine model is a good option because the ewes undergo Haversian remodeling, are a large sized animal, and have a similar hormone profile to humans. Ewes, however, do not undergo a natural menopause, so an ovariectomy surgery was conducted in the sheep to simulate the decreased levels in estrogen. Columbia-Rambouillet sheep were used in this study: some that have been ovariectomized as a model for postmenopausal osteoporosis and some that underwent a sham surgery to serve as a control. The sheep were sacrificed 12 months post operatively in the month of August, so the seasonal effects of remodeling were accounted for. The left radius was then processed into microradiographs of 6 regional cortical beams, where the cranial (tensile side) and caudal (compressive side) anatomical sections were analyzed in this study to determine regional differences in remodeling. Previous students' theses have analyzed the similar samples for basic bone remodeling histology measurements, resulting in some significant seasonal, anatomical, and treatment differences. However, most of the results showed no particular increase in the amount of remodeled area for the ovariectomized sheep compared to the sham sheep, even though an ovariectomy is believed to cause a burst of remodeling in bone due to the decreased levels in estrogen.v In this study, a new repeatable method was developed that further examines secondary bone by quantifying the extent to which secondary osteons encroach on previously-existing secondary osteons. Encroached and unencroached secondary osteons were quantified using two different methods: a point count method that measured the percentage of the area the encroached and unencroached secondary osteons inhabited and an osteon count method that measured the number of encroached and unencroached secondary osteons per area. These raw measurements were calculated into 18 parameters and 2-way repeated measures ANOVAs were run to determine the effects of surgery and anatomical region on each of the bone remodeling parameters. The results found significant effects from estrogen deletion which were different depending on if the bone region was predominately in compression or tension. The ovariectomy surgery caused an increase in remodeling, which was mostly confined on the compressive side to areas that have been previously remodeled, but on the tensile side, bone remodeling expanded into areas that used to be primary bone. The new secondary osteons, as a result of the ovariectomy surgery, were larger than in the control animals. There however, was not an increase in porosity from the ovariectomy surgery, which is one of the main characteristics o...

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“…For the two femur models, the boundary condition used was a pinned constraint at the distal end [20].…”

Section: Load and Boundary Conditionsmentioning

confidence: 99%

Finite Element Analysis and Validation of Hip Joints With the Main Types of Femoroacetabular Impingement

Mitchell¹

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Modeling the Long Term Effects of Alendronate on Bone Mass Preservation of the Femur with Articular Surface and Total Hip Replacements

Cited by 4 publications

References 61 publications

Development of a Subject Specific Finite Element Model Used to Predict the Effects of a Single Leg Extension Exercise

Development of a Subject Specific Finite Element Model Used to Predict the Effects of a Single Leg Extension Exercise

Effects of Ovariectomy and Anatomical Location on Osteonal Encroachment in Adult Cortical Ovine Bone

Finite Element Analysis and Validation of Hip Joints With the Main Types of Femoroacetabular Impingement

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