Real-World Rib Fracture Patterns in Frontal Crashes in Different Restraint Conditions

Objective: The purpose of this study was to use the detailed medical injury information in the Crash Injury Research and Engineering Network (CIREN) to evaluate patterns of rib fractures in real-world crash occupants in both belted and unbelted restraint conditions. Fracture patterns binned into rib regional levels were examined to determine normative trends associated with belt use and other possible contributing factors.Methods: Front row adult occupants with Abbreviated Injury Scale (AIS) 3+ rib fractures, in frontal crashes with a deployed frontal airbag, were selected from the CIREN database. The circumferential location of each rib fracture (with respect to the sternum) was documented using a previously published method (Ritchie et al. 2006) and digital computed tomography scans. Fracture patterns for different crash and occupant parameters (restraint use, involved physical component, occupant kinematics, crash principal direction of force, and occupant age) were compared qualitatively and quantitatively.Results: There were 158 belted and 44 unbelted occupants included in this study. For belted occupants, fractures were mainly located near the path of the shoulder belt, with the majority of fractures occurring on the inboard (with respect to the vehicle) side of the thorax. For unbelted occupants, fractures were approximately symmetric and distributed across both sides of the thorax. There were negligible differences in fracture patterns between occupants with frontal (0°) and near side (330° to 350° for drivers; 10° to 30° for passengers) crash principal directions of force but substantial differences between groups when occupant kinematics (and contacts within the vehicle) were considered. Age also affected fracture pattern, with fractures tending to occur more anteriorly in older occupants and more laterally in younger occupants (both belted and unbelted).Conclusions: Results of this study confirmed with real-world data that rib fracture patterns in unbelted occupants were more distributed and symmetric across the thorax compared to belted occupants in crashes with a deployed frontal airbag. Other factors, such as occupant kinematics and occupant age, also produced differing patterns of fractures. Normative data on rib fracture patterns in real-world occupants can contribute to understanding injury mechanisms and the role of different causation factors, which can ultimately help prevent fractures and improve vehicle safety.

研究目的：本研究借助碰撞损伤研究与工程网络（Crash Injury Research and Engineering Network, CIREN）收录的详细医疗损伤数据，针对真实世界碰撞事故中使用与未使用安全带约束的乘员，分析其肋骨骨折的分布模式。本研究将骨折模式按肋骨区域进行分类，旨在明确与安全带使用及其他潜在影响因素相关的标准化趋势。
研究方法：从CIREN数据库中筛选出符合以下条件的前排成年乘员：在正面碰撞中正面安全气囊已触发，且其肋骨骨折符合简明损伤定级量表（Abbreviated Injury Scale, AIS）评分≥3级的标准。借助既往发表的研究方法（Ritchie等，2006）与数字化计算机断层扫描（computed tomography, CT）影像，记录每一处肋骨骨折相对于胸骨的周向位置。针对不同碰撞与乘员参数（约束系统使用情况、碰撞接触部件、乘员运动学特征、碰撞主受力方向及乘员年龄）下的骨折模式，分别进行定性与定量对比分析。
研究结果：本研究共纳入158名使用安全带的乘员与44名未使用安全带的乘员。对于使用安全带的乘员，骨折主要集中在肩带的受力路径附近，多数骨折发生于胸腔的车内侧（相对于车辆而言）。未使用安全带的乘员则呈现骨折分布近似对称，且弥散于胸腔两侧。正面碰撞（主受力角度0°）与近侧碰撞（驾驶员侧主受力角度为330°~350°，乘客侧为10°~30°）的乘员之间，骨折模式差异可忽略不计；但当考虑乘员运动学特征（及车内接触情况）时，组间差异则十分显著。年龄同样会影响骨折模式：无论是否使用安全带，老年乘员的骨折更倾向于发生在胸腔前部，而年轻乘员则更多出现外侧骨折。
研究结论：本研究通过真实世界数据证实，在正面安全气囊已触发的碰撞事故中，未使用安全带的乘员肋骨骨折分布相较于使用安全带的乘员更为弥散且对称。乘员运动学特征与年龄等其他因素同样会导致骨折模式出现差异。真实世界乘员肋骨骨折模式的标准化数据，有助于深入理解损伤机制与各类致病因素的作用，最终可助力肋骨骨折预防与车辆安全性能提升。