Holcombe Sven A, Wang Stewart C, Grotberg James B
a Department of Biomechanical Engineering , University of Michigan , Ann Arbor , Michigan.
b International Center for Automotive Medicine , University of Michigan , Ann Arbor , Michigan.
Traffic Inj Prev. 2017 May 29;18(sup1):S122-S128. doi: 10.1080/15389588.2017.1309526. Epub 2017 Mar 23.
Both females and the elderly have been identified as vulnerable populations with increased injury and mortality risk in multiple crash scenarios. Particularly in frontal impacts, older females show higher risk to the chest and thorax than their younger or male counterparts. Thoracic geometry plays a role in this increase, and this study aims to quantify key parts of that geometry in a way that can directly inform human body models that incorporate the concept of person age.
Computed tomography scans from 2 female subject groups aged 20-35 and 65-99 were selected from the International Center for Automotive Medicine scan database representing young and old female populations. A model of thoracic skeletal anatomy was built for each subject from independent parametric models of the spine, ribs, and sternum, along with further parametric models of those components' spatial relationships. Parameter values between the 2 groups are directly compared, and average parameter values within each group are used to generate statistically average skeletal geometry for young and old females. In addition to the anatomic measures explicitly used in the parameterization scheme, key measures of rib cage depth and spine curvature are taken from both the underlying subject pool and from the resultant representative geometries.
Statistically significant differences were seen between the young and old groups' spine and rib anatomic components, with no significant differences in local sternal geometry found. Vertebral segments in older females had higher angles relative to their inferior neighbors, providing a quantification of the kyphotic curvature known to be associated with age. Ribs in older females had greater end-to-end span, greater aspect ratio, and reduced out-of-plane deviation, producing an elongated and overall flatter curvature that leads to distal rib ends extending further anteriorly in older individuals. Combined differences in spine curvature and rib geometry led to an 18-mm difference in anterior placement of the sternum between young and old subjects.
This study provides new geometric data regarding the variability in anthropometry of adult females with age and has utility in advancing the veracity of current human body models. A simplified scaffold representation of underlying 3-dimensional bones within the thorax is presented, and the reported young and old female parameter sets can be used to characterize the anatomic differences expected with age and to both validate and drive morphing algorithms for aged human body models. The modular approach taken allows model parameters to hold inherent and intuitive meaning, offering advantages over more generalized methods such as principal component analysis. Geometry can be assessed on a component level or a whole thorax level, and the parametric representation of thorax shape allows direct comparisons between the current study and other individuals or human body models.
女性和老年人已被确定为在多种碰撞场景中受伤和死亡风险增加的脆弱人群。特别是在正面碰撞中，老年女性胸部和胸腔的风险高于年轻女性或男性。胸廓几何形状在这种风险增加中起作用，本研究旨在以一种能够直接为纳入年龄概念的人体模型提供信息的方式，对该几何形状的关键部分进行量化。
从国际汽车医学扫描数据库中选取了20 - 35岁和65 - 99岁两个女性受试者组的计算机断层扫描图像，分别代表年轻和老年女性群体。利用脊柱、肋骨和胸骨的独立参数模型，以及这些组件空间关系的进一步参数模型，为每个受试者构建胸廓骨骼解剖模型。直接比较两组之间的参数值，并使用每组内的平均参数值生成年轻和老年女性的统计平均骨骼几何形状。除了参数化方案中明确使用的解剖测量外，胸廓深度和脊柱曲率的关键测量值既取自基础受试者群体，也取自生成的代表性几何形状。
年轻组和老年组的脊柱和肋骨解剖组件存在统计学上的显著差异，而局部胸骨几何形状未发现显著差异。老年女性的椎体节段相对于其下方相邻节段具有更高的角度，这对已知与年龄相关的驼背曲率进行了量化。老年女性的肋骨端到端跨度更大、长宽比更大且平面外偏差减小，形成了更长且整体更扁平的曲率，导致老年个体的肋骨远端向前延伸得更远。脊柱曲率和肋骨几何形状的综合差异导致年轻和老年受试者胸骨前部位置相差18毫米。
本研究提供了关于成年女性人体测量学随年龄变化的新几何数据，对提高当前人体模型的准确性具有实用价值。提出了胸廓内潜在三维骨骼的简化支架表示，报告的年轻和老年女性参数集可用于表征预期的年龄相关解剖差异，并验证和驱动老年人体模型的变形算法。所采用的模块化方法使模型参数具有内在和直观的意义，比主成分分析等更通用的方法具有优势。可以在组件级别或整个胸廓级别评估几何形状，胸廓形状的参数表示允许在当前研究与其他个体或人体模型之间进行直接比较。
