Time varying modulators of spine injury mechanics and material properties of the intervertebral disc

世界卫生组织将腰痛列为三大职业健康问题之一。80%的人在一生中的某个时候都会遭受腰痛的折磨，这使得腰痛成为影响加拿大普通人群的最普遍和最昂贵的肌肉骨骼问题。有证据表明，腰痛的主要原因是与日常活动和工业任务相关的机械暴露。虽然繁重的工作通常与腰痛有关，但看似久坐不动的工作，如长时间站立或坐着，也与腰痛有关。坐着和站着是工作场所常见的活动，由于自动化和越来越多的电脑使用，这些姿势的时间正在增加。本研究计划的总体目标是评估每日负荷暴露在腰背部组织损伤和疼痛产生中的作用。由于慢性暴露导致的脊柱结构（如椎间盘）损伤的开始和进展的原因将被调查。研究在进行久坐任务时对个体下背部的需求将与组织水平的调查相结合，以评估脊髓组织的时间依赖性反应和由此产生的损伤潜力。深入了解与机械负荷相关的损伤机制对于预防损伤至关重要，因为椎间盘的生物修复机制由于该结构缺乏血液供应而缓慢。一旦椎间盘损伤的第一阶段发生，脊髓组织自我修复的能力很容易被损伤恶化所超越。这项研究的结果将提供与时间相关的组织材料特性，这是目前无法获得的，也是理解和建模椎间和腰背部损伤的限制因素。最终，累积或慢性暴露与潜在疼痛产生的联系将是开发评估每日负荷和设置阈值限制或暴露标准以防止伤害的方法的有力和新颖的贡献。

The World Health Organization has deemed low back pain one of the top three occupational health problems. Eighty percent of the population will suffer from low back pain at some point in their life making low back pain the most prevalent and costly musculoskeletal problem affecting the general population of Canada. 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, seemingly sedentary tasks such as prolonged standing or sitting have also been associated with low back pain. Sitting and standing are common activities in the workplace and the time spent in these postures is increasing due to automation and increasing computer usage. The overall objective of this research program is to assess the role of daily loading exposures in the generation of low back tissue damage and pain. The causes of injury initiation and progression in the structures of the spine (e.g. the intervertebral disc) due to chronic exposure will be investigated. Studies examining the demands on the low back of individuals when performing sedentary tasks 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 injury mechanisms associated with mechanical loading is critical for injury prevention, as the biological repair mechanisms in the intervertebral disc are slow 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 intervertebral and low back injuries. Ultimately, the linking of cumulative or chronic exposure with potential pain generation would be a powerful and novel contribution in developing methods to assess daily loading and set threshold limits or exposure standards to prevent injuries.