Papers by Keyword: Micro Finite Element Analysis μ-FEA

Abstract: New medicines for treatment of osteoporotic bones have developed. In the previous studies, there were lots of pre-clinical experiments on animals to analyze the virtue of new medicine. However, the previous methods sacrificed a number of animals. They induced lots of expenses and ethical problems. In the present study, to investigate the effect of a medicine for osteoporosis by using in-vivo micro computed tomography (In-vivo Micro-CT, skyscan 1076, skyscan, Belgium) and micro finite element (*FE) analysis, morphological and mechanical characteristic changes of rat bone were detected and tracked. The 8 female Sprague-Dawley rats, used in the experiment, were randomized into 3 groups (Control, Sham and Risedronate group). The Risedronate (actonel, 0.58mg/Kg and 5days/week) for 8 weeks was administered in RIS group. The 4th lumbar vertebrae of rats were scanned by In-vivo Micro-CT with 35*m at week 0 (just before dose) and week 8 (after dose). Three-dimensional (3D) structural parameters were calculated. Simulated compression tests of 3D FE models were carried out to investigate the mechanical characteristics in the whole vertebral bone model of the 4th lumbar vertebra. The change rate of quantity and structure in Risedronate (RIS) group was smaller than that of control (CON) group. The change rate of structural modulus in RIS group was also smaller than that of CON group. This result shows the virtue of risedronate quantitatively as well as qualitatively. The study introduced the improved noninvasive biomechanical evaluation method, combined with In-vivo Micro-CT and *FE analysis, which was more effective and useful than the previous pre-clinical experiments.

Abstract: Several researchers investigated the mechanical characteristics of human trabecular bone using finite element analysis (FEA) based on micro computed tomography (μ-CT). There were few investigations on morphological and mechanical characteristics of vertebral trabecular bones. This study analyzed the relationship between morphological and mechanical characteristics in the regional vertebral trabecular bones using μ-CT and μ-FEA. Two specimens were obtained from the 12th thoracic vertebral bodies of cadavers (85 years female and 48 years male). In each vertebral body, fifteen regions were selected from two-dimensional (2D) images acquired from μ-CT. Voxelbased three-dimensional (3D) finite element models, with 4
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4 cubic block, were generated from each region for simulated compression test. The relationship between morphological characteristics, such as bone volume fraction, trabecular thickness, trabecular separation, trabecular number and structure model index, and mechanical characteristics, such as structural modulus (E†), was analyzed by bivariate correlation coefficient. As a result, the region of center column and inferior layer had the highest density. However, structural moduli in center column and middle layer were the biggest. The results indicated that there was a regional difference between morphological and mechanical characteristics of vertebral trabecular bone. In addition, for more exact evaluation of osteoporosis, it was recommended to analyze not only the mechanical characteristics but also the morphology characteristics.

Abstract: Considerable researchers analyzed the effects of hormone treatment on osteoporotic vertebral bones. Hormone treatment of age-related osteoporotic bone has a potential to decrease an incidence of osteoporosis. In the present paper, experimental and simulated tests for the mechanical characteristics of osteoporotic models and their hormone-treated models were investigated. Three dimensional (3D) geometries of the models (rapid prototyped and finite element models) were generated from high resolution micro-computed tomography ($-CT, Skyscan 1076, Skyscan, Belgium) scan data for the central parts of the second lumbar vertebrae. From these 3D geometries, cubic specimens with side length 6.5mm were formed and analyzed. Rapid prototyped (RP) models, instead of the real bone specimen, of vertebral trabecular bones were created in the fused deposition modeling (FDM) machine. In the present study, experimental compressions test for RP models were carried out by the INSTRON testing machine (8874 series, Instron, UK). The mechanical characteristics of finite element (FE) models for simulated compression tests were compared with physical predictions from RP models for experimental compression test. As a result, it is found that the hormone therapy is likely to be less effective than reported by previous researchers. A remarkable agreement was achieved between the results obtained from the experimental tests for RP models and simulated tests for FE models.