Aim. Bone changes in size and density in response to different levels of stress. Alterations to bone mineral density (BMD) appear to occur in a site specific manner. Even though BMD has been examined in many populations there is a paucity of data looking at strength-power athletes, such as throwers. Therefore, the purpose of this study was to examine the BMD of a group of USA Division I collegiate throwers (e.g. shot put, discus, etc.). Methods. Seven throwers (4 males; 3 females) who were 19.0 ± 0.9 years had their BMD compared to an age matched control group (n=14; 8 women and 6 men) and normative data. BMD was measured with dual X-ray absorptometry. Potential right/left side and sex difference in BMD were also examined. Maximal isometric strength was assessed using a mid-thigh pull while standing on a forceplate which generated force-time curves. Peak force (PF) and normalized peak force (PFa) were then correlated with BMDs. Results. Generally, throwers had denser bones with male throwers tending to have a greater total BMD (Ps<0.05). The dominant arm BMD was slightly greater when compared to non-dominant arm (P≤0.05). Furthermore, total body BMD was related to PF (r=0.68, r2 =0.46) and PFa (r=0.56, r2=0.31). Conlcusion. Throwers have greater BMDs than non-athletes and most other athletes. However, throwers only showed a small indication of sidedness. It is likely that the BMDs observed in this study stem from the training intervention (e.g. whole body heavy lifting) undertaken by this population.

AIM: Bone changes in size and density in response to different levels of stress. Alterations to bone mineral density (BMD) appear to occur in a site specific manner. Even though BMD has been examined in many populations there is a paucity of data looking at strength-power athletes, such as throwers. Therefore, the purpose of this study was to examine the BMD of a group of USA Division I collegiate throwers (e.g. shot put, discus, etc.). METHODS: Seven throwers (4 males; 3 females) who were 19.0 ± 0.9 years had their BMD compared to an age matched control group (n=14; 8 women and 6 men) and normative data. BMD was measured with dual X-ray absorptometry. Potential right/left side and sex difference in BMD were also examined. Maximal isometric strength was assessed using a mid-thigh pull while standing on a forceplate which generated force-time curves. Peak force (PF) and normalized peak force (PFa) were then correlated with BMDs. RESULTS: Generally, throwers had denser bones with male throwers tending to have a greater total BMD (P≤0.05). The dominant arm BMD was slightly greater when compared to non-dominant arm (P≤0.05). Furthermore, total body BMD was related to PF (r=0.68, r2 =0.46) and PFa (r=0.56, r2=0.31). CONCLUSIONS: Throwers have greater BMDs than non-athletes and most other athletes. However, throwers only showed a small indication of sidedness. It is likely that the BMDs observed in this study stem from the training intervention (e.g. whole body heavy lifting) undertaken by this population.

L'ostéoporose est une maladie du squelette caractérisée par une perte de la qualité osseuse qui entraîne un risque de fracture accru, notamment au niveau vertébral. Des modèles en éléments finis basés sur la tomodensitométrie permettent d'estimer la résistance vertébrale, et donc le risque de fracture, mais leur utilisation en routine clinique est limitée par le coût et l'irradiation engendrée par la tomodensitométrie. L'estimation la résistance vertébrale à partir d'un modèle en éléments finis basés sur l'imagerie basse dose, telle que l'absorptiométrie biphotonique à rayons X, ou la stéréo-radiographie EOS en double énergie, permettrait une utilisation en routine clinique. Cette thèse contribue au développement de la modélisation à partir de l'imagerie basse dose pour la prédiction du risque de fracture. Un modèle en éléments finis de résistance vertébrale y est évalué par rapport à un modèle basé sur la tomodensitométrie, et une étude de sensibilité identifie les facteurs importants du modèle sont analysés. Des méthodes de maillage hexaédrique morpho-réalistes à partir de la reconstruction 3D, et d'estimation de la distribution de densité à partir d'image 2D de densité y sont développées. De plus, profitant des possibilités du système EOS qui permet de radiographier le patient de la tête aux pieds, une méthode préliminaire est proposée pour estimer l'effort exercé sur les vertèbres in vivo. Nous espérons que nos méthodes pourront être utilisées très prochainement in vivo, et contribuer à l'estimation du risque de fracture ostéoporotique, et à la prise en charge des patients à risque de fracture. / Osteoporosis is a bone disease which decreases bone quantity and quality, and increases fracture risk, notably at the vertebral level. CT-scan-based finite element models allow predicting vertebral strength, and thus fracture risk, but their use in routine clinical practice is limited by the cost and accessibility of CT-scan. However, vertebral strength prediction from a finite element model based on low dose images, such as dual X-ray absorptiometry or EOS stereo-radiography in dual energy, would allow a wider use. This PhD thesis contributes to develop fracture risk estimation by such a model. The low dose approach is evaluated in comparison to CT-based finite element model, and a sensitivity study is performed to identify the most important parameters of the model. Hexahedral morpho-realistic meshing techniques from 3D reconstruction and estimation methods for the 3D bone mineral density distribution from low dose images are developed and evaluated. Moreover, taking advantage of EOS system's possibility to take full body radiographs in standing position, a preliminary method is proposed to estimate the load applied to vertebra in vivo. We hope those methods will be used soon in vivo, and will contribute to estimating osteoporotic fracture risk estimation in clinical situations.

Title: Bone density in people after spinal cord injury Objective: The purpose of this paper is to determine the levels of bone mineral density in people following a spinal cord injury. The levels are measured using a DXA device and the results are subsequently evaluated. Methods: The thesis is composed of eight independent case studies. A non-standardized 14 open and closed question survey was used for quantifying purposes. Answering the questions was a necessary prerequisite for participation in the survey. The measured results of bone density and body composition were used for data analysis, together with the survey, in comparison with other studies. Results: Eight probands (four women and four men) participated in the research. Based on the obtained data, we can state that all probands (n=8) record a decrease in bone mineral density to the level of Osteopenia. Better bone mineral density measurements have not been confirmed in individuals with lower spinal cord lesions. Probands who regularly engaged in sports and daily training before spinal injuries have better results in densitometric measurements. Furthermore, it can be confirmed that probands with a past compression fracture have worse measurement results than probands without a past fracture. However, due to the low number of measured...