Bone creep can cause progressive vertebral deformity
Bone creep can cause progressive vertebral deformity
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DOI：
10.1016/j.bone.2009.05.015
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发表时间：
2009-09-01
期刊：
影响因子：
4.1
通讯作者：
Adams, Michael A.
中科院分区：
文献类型：
--
作者：
Pollintine, Phillip;Luo, Jin;Adams, Michael A.
老年人的椎体畸形通常被称为“骨折”，但它们的发病往往是潜伏的，表明时间依赖性（蠕变）过程也可能参与其中。蠕变已经在小样本骨中进行了研究，但对整个椎骨的蠕变畸形以及它如何受到骨矿物质密度（BMD）的影响一无所知。我们假设持续的压缩载荷可以导致进行性和可测量的老年人椎骨蠕变畸形。方法：选取20具年龄42 ~ 91岁的人尸体，解剖27节胸腰椎“运动节段”（2节椎骨及中间椎间盘和韧带）。对每个标本施加约1.0 kN的恒定压缩力0.5 h或2 In，同时使用MacReflex 2D光学跟踪系统以1 Hz的频率测量54个椎体中的每个椎体的前、中、后高度。该方法定位了附着在每个椎体外侧皮质的6个反射标记，分辨率优于10pm。实验在实验室温度下进行，并使用聚乙烯薄膜来减少水分损失。计算每个椎体的体积骨密度，使用DXA测量矿物质含量，水浸泡测量体积。结果：在0.5 h的试验中，椎体前、中、后皮层的蠕变变形平均分别为4331、1629和614微应变，其中10000微应变代表高度损失1%。前蠕变应变大于后蠕变应变
Introduction: Vertebral deformities in elderly people are conventionally termed "fractures", but their onset is often insidious, suggesting that time-dependent (creep) processes may also be involved. Creep has been studied in small samples of bone, but nothing is known about creep deformity of whole vertebrae, or how it might be influenced by bone mineral density (BMD). We hypothesise that sustained compressive loading can cause progressive and measurable creep deformity in elderly human vertebrae.Methods: 27 thoracolumbar "motion segments" (two vertebrae and the intervening disc and ligaments) were dissected from 20 human cadavers aged 42-91 yrs. A constant compressive force of approximately 1.0 kN was applied to each specimen for either 0.5 h or 2 In, while the anterior, middle and posterior heights of each of the 54 vertebral bodies were measured at 1 Hz using a MacReflex 2D optical tracking system. This located 6 reflective markers attached to the lateral cortex of each vertebral body, with resolution better than 10 pm. Experiments were at laboratory temperature, and polythene film was used to minimise water loss. Volumetric BMD was calculated for each vertebral body, using DXA to measure mineral content, and water immersion for volume.Results: In the 0.5 h tests, creep deformation in the anterior, middle and posterior vertebral cortex averaged 4331, 1629 and 614 micro-strains respectively, where 10,000 micro-strains represents 1% loss in height. Anterior creep strains exceeded posterior (P