冲击载荷下骨盆后环结构失效致血管损伤机制研究

Vascular injury of Posterior pelvic ring is the leading cause of death for patients with pelvic injuries. Assessing the severity of pelvic injuries is an important way to predict vascular injury. It was observed in our previous clinical study that the severity of vascular injury was not completely consistent to the severity of posterior pelvic ring injury. Except for pelvic injury, it was also reported that the severity of vascular injury related to the fracture site, fracture displacement and its mechanism of injury in recent anatomical study home and abroad. The location and type of impact loading are also associated with vascular injury based on finite element analysis studies. The study focusing on the failure mechanism of the posterior pelvic ring and vessels, will contribute to clarify the relationship between the posterior pelvic injury and vascular injury, and to achieve a higher success rate of early diagnosis and treatment of vascular injuries. To solve this problem, this study will focus on blood vessels of posterior pelvic ring, and develop a more intact and highly biofidelic 3D pelvic finite element model including the pelvic ring, vessels, skin and subcutaneous tissues. And, this study will research the biomechanical reaction of main structure and vessels of posterior pelvic ring model under side and saggital impact. Fresh cadaver models and retrospective analysis of traffic injuries will be performed to validate the results derived from the finite element model. By clarifying the biomechanical effect and the failure mechanisms of main structure and vessels of posterior pelvic ring, this study will explore the correlation between structural damage and vascular injuries.

血管损伤是不稳定型骨盆骨折早期最主要的致死因素。骨盆损伤严重程度是预测血管损伤的重要指征，然而，课题组前期临床研究发现部分骨盆损伤严重程度与血管损伤程度并不相关，国内外亦有类似报道。既往研究发现而血管损伤不仅与骨盆损伤的严重程度，还与骨折部位、位移及损伤机制相关；有限元动态分析提示，血管损伤亦与致伤部位及冲击载荷特征相关。明确周围结构致伤情况与血管损伤之间的联系，有利于血管损伤的准确预测，而其尚未被明确表达。基于上述问题，本项目拟以骨盆后方血管作为研究对象，建立包含骨盆环、血管和周围软组织等的全骨盆有限元模型，并通过尸体实验和交通伤典型案例分析对有限元结果进行验证。在此基础上对模型施加侧方及前后方冲击载荷，获取骨盆后环结构及血管的冲击响应谱，明确骨盆后环结构失效致血管损伤的机制，探究后环结构损伤与血管损伤之间的联系，以期预测骨盆血管损伤，提高临床救治成功率。

本课题基于 CT 扫描数据，构建了包含血管的全骨盆有限元模型。其中包含以下组织结构：髂骨、骶骨、第 3-5 腰椎、股骨上部；骶髂关节软骨、耻骨间盘；韧带； 臀部、腹壁区域的皮肤、皮下组织、肌肉等软组织；包含盆部髂总动静脉、髂内动静脉、髂外动静脉及其主要分支，获得了经过验证的精确的具有更高生物相似性的全骨盆有限元模型。通过测量人体多部位松质骨矿物质密度、轴向弹性模量，建立了矿致密度与轴向弹性模量相关关系的本构方程，为中国人有限元材料属性赋值提供了依据，该研究表明各个部位矿致密度与轴向弹性模量的线性和幂次回归的相关性均较高，且同部位两种回归的r^2值之间无明显差异，说明本研究可以应用于体外检测患者的骨骼质量，准确分辨骨质变化的部位，配合有限元建模预测骨折风险。构建并验证了含动脉的骨盆股骨软组织复合体的三维有限元模型，研究骨盆动脉在侧向冲击条件下的力学响应。采用线弹性 实体单元模拟骨骼，采用非线性的弹性连接单元模拟韧带，软组织包括软骨、包裹软组织和动脉等采用超弹性材料和实体单元仿真。运用Mimics、Geomagics、 Hypermesh、UG等软件建立标准骨盆模型、骨盆Tile B2型损伤模型、钢板固定骨盆骨折模型以及“2钉”与“3钉”钉-棒系统固定模型。利用上述研究成果，本课题针对临床问题进行应用研究，探讨髋臼骨折内固定危险区域安全置钉的方法， 降低螺钉穿入髋关节的风险。