Age-related Changes in Thoracic Spine Biomechanics

描述(申请人提供)：脊椎骨折是老年人中最常见的骨折，发生在50岁以上的女性中有20%-35%，男性中有15%-25%，在美国，脊椎骨折与严重的发病率、增加的死亡率和超过10亿美元的年成本有关。然而，除了骨质疏松症导致的骨强度低下外，人们对导致脊椎骨折的因素了解有限，这阻碍了我们预测和预防这些损伤的能力。一种无法解释的观察是，某些部位的脊柱骨折比其他部位更常见，特别是胸中(T7-T8)和胸腰椎(T12-L1)。已经有人提出，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被探索。根据我们的初步数据，我们假设肋骨笼的生物力学效应和增加的胸椎后凸(脊柱弯曲)分别导致胸中和胸腰椎区域更大的椎体负荷。因此，这些因素的年龄相关变化可能会增加这些地区与年龄相关的脊椎骨折的风险。在这个项目中，我们将研究肋骨、肋骨僵硬和胸椎后凸对椎体负荷的影响。首先，我们将对身体胸椎标本进行体外力学测试研究，以确定肋骨笼对椎体负荷的影响，以及更坚硬的肋骨笼是否会增加胸椎中段的椎体负荷。其次，我们将进行一项活体人体研究，以确定年龄和胸椎后凸过长与胸椎活动范围(作为胸椎僵硬的衡量标准)之间的关系。此外，我们将确定胸椎僵硬和后凸对估计的椎体负荷的影响，以确定中胸椎和胸腰椎的负荷是否增加。这些研究中收集的数据，包括从开放的直立磁共振成像设备上对胸椎运动学的活体测量，将被用于开发和验证独特的胸椎肌肉骨骼模型，该模型将用于估计脊椎负荷，同时考虑肋骨和脊柱曲率的影响。胸椎生物力学信息的广泛缺乏以前阻碍了这种模型的发展和验证，这对于理解胸椎生物力学将是非常重要的。总体而言，在这项工作中获得的知识和创建的模型将推进更好地了解脊椎骨折原因的长期目标，最终导致改进预测和预防脊椎骨折的方法，这将改善数百万老年人的健康和生活质量。此外，胸椎生物力学知识的增加，以及胸椎肌肉骨骼模型的可获得性，将支持其他领域的未来研究，如背痛、工作场所和创伤、手术规划和康复。

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.