Age-related Changes in Thoracic Spine Biomechanics

描述（由申请人提供）：椎体骨折是老年人中最常见的骨折，发生在20-35%的女性和15-25%的50岁以上男性中，并且与显著的发病率和死亡率增加相关，在美国每年的费用超过10亿美元。然而，除了骨质疏松导致的骨强度低外，对导致椎体骨折的因素了解有限，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，椎体骨折更常发生在某些部位，特别是中胸椎（T7-T8）和胸腰椎（T12-L1）椎体。有人认为，生物力学因素通过增加椎体负荷使这些区域易发生骨折，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，我们假设胸腔的生物力学效应和增加的胸椎后凸（脊柱弯曲）分别导致胸椎中部和胸腰椎区域的椎体负荷增加。这些因素与年龄相关的变化可能因此增加这些区域与年龄相关的椎体骨折的风险。在这个项目中，我们将检查胸腔、胸腔刚度和胸后凸如何影响椎体负荷。首先，我们将对尸体胸椎标本进行体外力学试验研究，以确定胸腔对椎体载荷的影响，以及更硬的胸腔是否会增加中胸椎的椎体载荷。其次，我们将进行一项人体研究，以确定年龄和胸椎后凸过度与胸椎活动度（作为胸椎僵硬度的测量指标）之间的关系。此外，我们将确定胸椎刚度和后凸对估计椎体负荷的影响，以确定中胸椎和胸腰椎的负荷是否增加。在这些研究中收集的数据，包括通过一个开放的、直立的磁共振成像设备对胸椎运动学的体内测量，将用于开发和验证一个独特的胸椎肌肉骨骼模型，该模型将用于估计椎体负荷，同时考虑胸腔和脊柱弯曲的影响。胸椎生物力学信息的广泛缺乏阻碍了这种模型的发展和验证，这对理解胸椎生物力学非常重要。总的来说，在这项工作中获得的知识和创建的模型将促进更好地理解椎体骨折原因的长期目标，最终导致预测和预防椎体骨折的改进方法，这将改善数百万老年人的健康和生活质量。此外，胸生物力学知识的增加和胸椎肌肉骨骼模型的可用性将支持其他领域的未来研究，如背部疼痛、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.