颌面撞击伤对颅底损伤的生物力学分析

Biomechanics analysis of the impact of maxillofacial injury on skull base damage

目的建立人颌面部撞击伤有限元模型，并对颌面部撞击伤时颅底损伤过程进行仿真动态模拟，初步分析颌面撞击伤时颅底损伤的机制。方法利用CT扫描数据建立人颅颌面骨的三维有限元模型，计算机设计底面直径3cm的铅质圆柱体为撞击物，动态模拟右侧上颌骨、左侧眶下缘、左侧颧骨体3个部位遭受8．6m／s（约30km／h）的速度撞击的过程；选取颅底13个标志点，获取这些标志点在0．5、1．0、1．5及2．0ms末应力值的大小与最大应力值，对计算结果进行综合分析。结果成功模拟了面部3个部位遭受相同条件撞击时颌骨骨折的动态过程及颅底骨应力分布和传导情况；右侧上颌骨遭受撞击时，右圆孔内侧（B）、左圆孔内侧（b）、斜坡前点（I）的应力值在各时间节点均为峰值，0．5ms末分别为26．2、22．4、21．5MPa，1．0ms末为70．0、55．0、45．0MPa，1．5ms末为38．0、26．5、39．5MPa，2．0ms末为26．0、19．0、23．0MPa；左侧眶下缘遭受撞击时，左圆孔内侧（b）、斜坡后点（J）的应力值在各时间节点均为峰值，0．5ms末为8．8、16．0MPa，1．0ms末为10．0、18．0MPa，1．5ms末为5．5、6．0MPa，2．0ms末为11．5、12．5MPa；左侧颧骨体遭受撞击时斜坡后点（J）在各时间节点均为峰值，0．5、1．0、1．5、2．0ms分别为45．0、40．0、12．0、42．5MPa。结论面部不同部位遭受相同条件撞击时，颅底的应力集中区及承受的应力大小均不同，应力传导至颅底的速度和路径也不相同。有限元动态仿真可用于颌面撞击伤对颅底损伤的生物力学研究，为探讨颌面部不同致伤条件下颅底的损伤部位和严重程度提供了可靠手段。

Objective To analyze the impact of maxillofacial injury on skull base. Methods A three-dimensional（3D） finite-element model of cranio-maxillofacial bone was established by CT scan data. A lead cylinder in base diameter of 3 cm was designed as an impaetor. There regions（upper right maxilla, left infraorbital margin and left zygomatic body） subjected to an impact at the speed of 8.6 rrds（about 30 kin/h） was simulated. Thirteen landmarks at the skull base were selected. The values of stress at the end of 0.5, 1.0, 1.5, 2.0 ms were obtained, and the results were analyzed. Results The dynamic process of the fracture of the jaw and the stress distribution and conduction of the skull base were successfully simulated in three parts of the face. When the impact was on the right maxillary bone region, the stress values of the three points （medial foramen rotundum, medial foramen rotundum, anterior clivus reached the peak at each time point, 26.2, 22.4, 21.5 MPa（t=0.5 ms） and 70.0, 55.0, 45.0 MPa（t=l.0 ms） and 38.0, 26.5, 39.5 MPa（t=l.5 ms） and 26.0, 19.0, 23.0 MPa（t=2.0 ms）, respectively. When the impact was on the left margo infraorbitalis orbitaeta region, the stress values of the two points（medial left foramen rotundum, posterior clivus） reached the peak at each time point, 8.8, 16.0 MPa（t=0.5 ms） and 10.0, 18.0 MPa（t=l.O ms） and 5.5, 6.0 MPa（t=l.5 ms） and 11.5, 12.5 MPa（t=2.0 ms）, respectively. When the impact was on the body of left zygomatic bone, the stress values of posterior clivus were 45.0 MPa（t=0.5 ms）, 40.0 MPa（t=l.O ms）, 12.0 MPa（t=l.5 ms）, 42.5 MPa（t=2.0 ms）, respectively. Conclusions According to the difference of stress distribution and conduction of maxillofacial and skull base bone, the speed and the path of force transfer to the skull base were different. Finite-element dynamic simulation can be used for the biomechanics research on maxillofacial trauma.