Trefoil factor family 3 (Tff3) peptide is present during intrauterine endochondral ossification in mice, and its deficiency affects cancellous bone quality in secondary ossification centers of mouse tibiae. The aim of this study was to quantitatively analyze parameters describing the growth plate and primary ossification centers in tibiae of 1-month-old wild-type and Tff3 knock-out mice (n=5 per genotype) by using free and open-source software. Digital photographs of the growth plates and trabecular bone were processed by open-source computer programs GIMP and FIJI. Histomorphometric parameters were calculated using measurements made with FIJI. Tff3 knock-out mice had significantly smaller trabecular number and significantly larger trabecular separation. Trabecular bone volume, trabecular bone surface, and trabecular thickness showed no significant difference between the two groups. Although such histomorphological differences were found in the cancellous bone structure, no significant differences were found in the epiphyseal plate histomorphology. Tff3 peptide probably has an effect on the formation and quality of the cancellous bone in the primary ossification centers, but not through disrupting the epiphyseal plate morphology. This work emphasizes the benefits of using free and open-source programs for morphological studies in life sciences.

Three 10-mm-long miniscrews commonly employed in orthodontic treatment were compared in four different situations involving diverse thicknesses of cortical bone. The finite element method (FEM) was used in the study, in which a force of 250 g was applied in two directions: perpendicular and parallel to the bone surface. As the parameter under study was the thickness of cortical bone, simulations were performed in four different bone loss situations: 2.5, 2, 1.5 and 1 mm. Our aim was also to quantify the stresses and displacements generated when applying a force of 250 g perpendicular and parallel to the bone surface under the same skeletal conditions. The results reveal similar performance in the three analysed samples, with increased stresses and displacements in the surrounding bone in relation to similar variations in the thickness of cortical bone.

Osteoporosis is a disease characterized by a loss of bone density and an altered bonearchitecture. These modifications lead to an increased risk factor for bone fracture,particularly of the femoral neck. This disease can be explained by a disorder in the boneremodeling process which is triggered by the apparition of micro-cracks within the bone.According to Frost’s theory [1], these micro-cracksappear for a specific local strain threshold. Thus, the knowledge of the microarchitectureand quality of trabecular bone is essential to determine this local strain threshold. Thispaper studied the mechanical trabecular bone behavior of 43 patients diagnosed asosteoporotic whose femoral heads were replaced by hip prosthesis. From each patient, acylinder-shaped of trabecular bone samples was cored. Each sample was scanned by X-raymicro-tomography before a compression test in order to reconstruct a reliableFinite-Element (FE) model of the bone architecture in Abaqus. The force-displacementcurves were recorded for all the samples and calibrated by the experimental responses. Theforce-displacement numerical curves were adjusted to the experimental ones, by modifyingthe tissue microscopic mechanical behavior. This process leads to the determination of thelocal strain threshold responsible for triggering the bone remodeling process.

Afin d’optimiser la sécurité des usagers de la route, les constructeurs automobiles ontde plus en plus recours à des modèles virtuels de l’être humain. Pour accroître labio-fidélité de ces modèles, nous nous proposons d’identifier le comportement mécaniquedes tissus osseux, et plus particulièrement celui de l’os trabéculaire. Après acquisitionpar micro-tomographie de l’architecture d’échantillons d’os spongieux, des essaismécaniques de compression sont menés. L’influence des variabilités inter etintra-individuelles est étudiée afin de minimiser la dispersion des résultats. Des modèlesnumériques obtenus à partir des données micro-tomographiques sont ensuite générés afind’étudier l’influence des principales propriétés architecturales sur le comportementmécanique du tissu trabéculaire. Les résultats expérimentaux et numériques obtenus mettenten évidence la nécessité de prendre en compte l’effet des variabilités inter etintra-individuelles afin d’identifier précisement le comportement mécanique de l’ostrabéculaire. Si la densité relative apparait comme un paramètre prépondérant justifiantdes variations mécaniques constatées, elle ne permet pas d’expliquer les différences decomportement observées selon la direction de chargement.