Age-related Changes in Thoracic Spine Biomechanics

描述（由申请人提供）：椎骨骨折是老年人中最常见的骨折，在50岁以上的女性中有20-35%，男性中有15-25%，在美国，椎骨骨折与显著的发病率、死亡率增加和超过10亿美元的年成本相关。然而，除了由于骨质疏松症导致的骨强度低之外，对导致椎骨骨折的因素的了解有限，阻碍了我们预测和预防这些损伤的能力。一个无法解释的观察结果是，椎骨骨折更常发生在某些位置，特别是中胸椎（T7-T8）和胸腰椎（T12-L1）椎骨，而不是其他位置。有人认为，生物力学因素通过增加椎体负荷使这些区域易于骨折，但这些想法在很大程度上仍未得到探索。根据我们的初步数据，我们假设肋骨架的生物力学效应和胸椎后凸（脊柱弯曲）增加分别导致胸椎中部和胸腰椎区域的椎体负荷增加。因此，这些因素中与年龄相关的变化可能会增加这些地区与年龄相关的椎骨骨折的风险。在这个项目中，我们将研究如何肋骨架，肋骨架刚度和胸椎后凸影响椎体负荷。首先，我们将对尸体胸椎标本进行体外力学测试研究，以确定肋骨架对椎体载荷的影响，以及更硬的肋骨架是否会增加中胸椎的椎体载荷。其次，我们将进行一项人体内研究，以确定年龄和胸椎过度后凸与胸椎活动度（作为胸椎刚度的测量）的相关性。此外，我们将确定胸椎僵硬和脊柱后凸对估计的椎体载荷的影响，以确定中胸椎和胸腰椎的载荷是否增加。这些研究中收集的数据，包括开放式直立磁共振成像设备的胸椎运动学的体内测量，将用于开发和验证胸椎的独特肌肉骨骼模型，该模型将用于估计椎骨负荷，同时考虑肋骨架和脊柱弯曲的影响。广泛缺乏有关胸椎生物力学的信息，以前阻碍了这样一个模型的发展和验证，这将是非常重要的理解胸椎生物力学。总的来说，这项工作中获得的知识和创建的模型将推进更好地了解椎骨骨折原因的长期目标，最终导致预测和预防椎骨骨折的方法得到改进，这将改善数百万老年人的健康和生活质量。此外，增加胸部生物力学的知识，并提供一个有效的肌肉骨骼模型的胸椎，将支持未来的研究在其他领域，如背痛，工作场所和创伤性损伤，手术计划和康复。

DESCRIPTION (provided by applicant): Vertebral fractures are the most common fracture in older adults, occurring in 20-35% of women and 15-25% of men over the age of 50, and are associated with significant morbidity, increased mortality, and annual costs exceeding $1 billion in the United States. However, outside of low bone strength due to osteoporosis, there is limited understanding of the factors that cause vertebral fractures, hindering our ability to predict and prevent these injuries. An unexplained observation is that vertebral fractures occur more often in some locations, specifically mid-thoracic (T7-T8) and thoraco-lumbar (T12-L1) vertebrae, than others. It has been suggested that biomechanical factors predispose these areas to fracture by increasing vertebral loading, but these ideas remain largely unexplored. Based on our preliminary data, we hypothesize that the biomechanical effects of the rib cage and increased thoracic kyphosis (spinal curvature) result in greater vertebral loading in the mid- thoracic and thoraco-lumbar spinal regions, respectively. Age-related changes in these factors may thus increase the risk of age-related vertebral fractures in these regions. In this project, we will examine how the rib cage, rib cage stiffness and thoracic kyphosis affect vertebral loading. First we will conduct an in vitro mechanical testing study of cadaveric thoracic spine specimens to determine the effects of the rib cage on vertebral loading, and whether a stiffer rib cage increases vertebral loading in the mid-thoracic spine. Second, we will perform an in vivo human subjects study to determine the association of age and thoracic hyperkyphosis with thoracic range of motion (as a measure of thoracic stiffness). Furthermore, we will determine the influence of thoracic stiffness and kyphosis on estimated vertebral loading, to determine if loading is increased in the mid-thoracic and thoraco-lumbar vertebrae. The data collected in these studies, including in vivo measurements of thoracic vertebral kinematics from an open, upright magnetic resonance imaging device, will be used to develop and validate of a unique musculoskeletal model of the thoracic spine, which will be used to estimate vertebral loading while accounting for the effects of the rib cage and spinal curvature. The broad lack of information on thoracic biomechanics has previously stymied the development and validation of such a model, which will be of great importance in understanding thoracic spine biomechanics. Overall, the knowledge gained and model created in this work will advance the long term goal of better understanding of the causes of vertebral fractures, ultimately leading to improved methods of predicting and preventing vertebral fracture that will improve health and quality of life for millions of older adults. Furthermore, increased knowledge of thoracic biomechanics, and the availability of a well-validated musculoskeletal model of the thoracic spine, will support future research in other areas such as back pain, workplace and traumatic injuries, surgical planning and rehabilitation.