Richards Darrin, Carhart Michael, Raasch Christine, Pierce Janine, Steffey Duane, Ostarello Andrew
Exponent Failure Analysis Associates, Phoenix, Arizona, USA.
Annu Proc Assoc Adv Automot Med. 2006;50:125-39.
The increased utilization of three-point restraint systems has greatly reduced the incidence of spinal injuries in motor vehicle accidents. Nevertheless, several studies which rely upon the National Automotive Sampling System (NASS) have documented lower thoracic and upper lumbar fractures in restrained occupants involved in frontal collisions of moderate severities. Although it has been postulated that the injury mechanism may be related to the occupant being out-of-position or sitting in an unusual posture, conclusions with regard to the precise mechanism of injury are difficult due to the lack of information contained in the NASS database. In addition, previous studies have not reported statistical significance of these injuries. In this study, we combined statistical analysis of frontal collisions in the NASS database with the analysis of data acquired from sled and crash tests, which utilized anthropomorphic test devices (ATDs), in order to evaluate the incidence and potential injury mechanisms underlying thoracic and lumbar spine fractures in moderate frontal impacts. In the first portion of the study, we performed a statistical analysis of the NASS database to estimate the incidence rate of spinal fracture. This was complemented with measurements and analysis of lumbar spine load data derived from frontal sled and crash tests. Analysis of the NASS database demonstrated that thoracolumbar spinal injuries are rare when an occupant is restrained by a lap and shoulder belt, and are often accompanied by abdominal injury. The spinal loads measured during frontal impacts with restrained and nominally positioned ATDs were found to be well below injury thresholds. Our results also suggest that the potential for isolated fracture is increased when the geometry of occupant-to-restraint interaction is compromised, as occurs when an occupant submarines the lap belt.
三点式约束系统使用的增加，已大大降低了机动车事故中脊柱损伤的发生率。然而，几项依赖国家汽车抽样系统（NASS）的研究记录了在中度严重程度的正面碰撞中，受约束乘客的下胸椎和上腰椎骨折情况。尽管有人推测损伤机制可能与乘客位置不当或坐姿异常有关，但由于NASS数据库中缺乏相关信息，关于确切损伤机制的结论难以得出。此外，以往的研究并未报告这些损伤的统计学意义。在本研究中，我们将NASS数据库中正面碰撞的统计分析与从雪橇试验和碰撞试验中获取的数据（这些试验使用了人体模型试验装置（ATD））分析相结合，以评估中度正面碰撞中胸腰椎骨折的发生率及潜在损伤机制。在研究的第一部分，我们对NASS数据库进行了统计分析，以估计脊柱骨折的发生率。这一分析辅以对从正面雪橇试验和碰撞试验得出的腰椎负荷数据的测量和分析。对NASS数据库的分析表明，当乘客使用腰部和肩部安全带时，胸腰椎损伤很少见，且常伴有腹部损伤。在对受约束且位置正常的ATD进行正面碰撞时测得的脊柱负荷，被发现远低于损伤阈值。我们的结果还表明，当乘客与约束装置的相互作用几何关系受到破坏时，如乘客从腰部安全带下方滑出时，孤立骨折的可能性会增加。
