Time-Varying Material Properties of the Intervertebral Disc and the Influence on Spine Joint Mechanics

下背痛影响大约80%的人口在他们生命中的某个时候。下背部是最常受伤的身体部位，平均赔偿成本最高，导致的全球残疾比任何其他疾病都多。有证据表明，腰痛的主要原因是通过与日常活动和工业任务相关的机械暴露。虽然涉及举重的任务通常与腰痛有关，但无害的久坐任务，如长时间站立或坐着，也与腰痛有关。然而，很少有人了解这些久坐不动，看似良性的任务如何导致下背部受伤。 我的研究计划的总体方向是调查如何随时间变化暴露于低水平负荷启动和加剧改变关节机械性能贷款洞察这些下背部损伤途径。将研究慢性暴露导致健康脊柱结构（例如椎间盘）损伤开始和进展的原因。椎间盘的机械损伤被认为是造成高达50%的慢性腰痛病例的原因。研究检查健康、无损伤的个人在执行代表坐式和站立式办公室电脑或灯光装配工作的久坐任务时对下背部的需求，将与组织水平的调查相结合，以评估脊柱组织的时间依赖性反应以及由此产生的伤害可能性。对关节性能和与机械负荷相关的损伤机制的联系的深入了解对于损伤预防至关重要，因为椎间盘中的生物修复机制比损伤过程慢，部分原因是缺乏对该结构的血液供应。一旦发生椎间盘损伤的第一阶段，脊柱组织的自我修复能力很容易被损伤恶化所超越。 这项研究的结果将提供目前不可用的时间依赖性组织材料特性，这些特性是椎间盘和腰部损伤的理解和建模的限制因素。最终，累积或慢性暴露与潜在疼痛产生的联系将是一个强大的和新颖的基本贡献，在开发方法，以评估每日负荷和设定阈值限制或暴露标准，以防止伤害久坐不动的任务。这项工作将提供下背部潜在健康组织反应的知识，为制定涉及坐立组件的职业工作站使用指南奠定基础。

Low back pain affects approximately 80% of the population at some point in their life. The low back is the most frequently injured body area, has the highest average compensation costs, and results in more global disability than any other condition. Evidence suggests that the primary cause of low back pain is through mechanical exposure associated with everyday activities and industrial tasks. While tasks involving heavy lifting are often linked with low back pain, innocuous sedentary tasks such as prolonged standing or sitting have also been associated with low back pain. However, there is little understanding of how these sedentary, and seemingly benign tasks can result in injuries to the low back. The overall direction of my research program is to investigate how time varying exposure to low level loading initiates and exacerbates altered joint mechanical performance lending insight to these low back injury pathways. The causes of injury initiation and progression in the structures of the healthy spine (e.g. the intervertebral disc) due to chronic exposure will be investigated. Mechanical injuries to the intervertebral disc are thought to be responsible for up to 50% of chronic low back pain cases. Studies examining the demands on the low back of healthy, injury free individuals when performing sedentary tasks representing sitting and standing office computer or light assembly work will be combined with investigations at the tissue level to assess time-dependent responses of spinal tissues and the resulting injury potential. A solid understanding of the joint performance and links to injury mechanisms associated with mechanical loading is critical for injury prevention, as the biological repair mechanisms in the intervertebral disc are slower than the injury process, in part due to the lack of blood supply to this structure. The ability of the spinal tissues to repair themselves can easily be outpaced by injury deterioration once the first stage of an injury to the intervertebral disc has occurred. The outcomes from this research will provide time-dependent tissue material properties that are currently unavailable and are a limiting factor in the understanding and modeling of the intervertebral disc and low back injuries. Ultimately, the linking of cumulative or chronic exposure with potential pain generation would be a powerful and novel fundamental contribution in developing methods to assess daily loading and set threshold limits or exposure standards to prevent injuries for sedentary tasks. This work will provide knowledge of the underlying healthy tissue response in the low back, laying a foundation to develop usage guidelines for occupational workstations involving sit to stand components.