颅面骨撞击伤的生物力学研究

Biomechanical study on impact maxilla injuries

目的 建立具有生物力学特性的动态颅面骨三维有限元模型 ,在上颌骨正面撞击时响应过程 ,探讨颅面骨外伤骨折的生物力学基础。 方法 采用GELightspeed多层螺旋CT对 1例无牙颌患者从眉上到下颌骨下缘CT扫描 ,三维影像重建 ,数据转换 ,运用自编程序和Nastran软件相结合方法 ,模仿刚体撞击上颌骨正面。获得颅面骨三维有限元生物医学模型 ,分析在正面撞击时颅面骨各部位应力改变。 结果 当着力点位于上颌骨 ,应力沿上颌骨、翼突、颧骨向颞骨颅底传导 ,同样也会影响颞下颌关节 ,髁突及髁突颈部应力有明显改变 ,骨结构的横截面积陡然减小的区域出现应力集中。撞击波呈梯度向后传导 ,在寰枕关节处应力集中 ,明显变化。 结论 撞击波造成各部分应力改变会在骨缝连接处和骨关节处集中 ,出现传导改变和传导中断 ,形成较强大的应力梯度 ,游离端出现应力回弹 ,相应的张应力、剪应力易导致骨折的发生。而此处即为损害较严重的区域。撞击点处主要为压缩破坏 ,撞击点背面的骨组织为拉伸破坏 ,髁突等游离端主要为拉伸破坏 ,从理论上 ,这可能是撞击伤的生物力学机制之一。

Objective To establish three-dimensional finite eleme nt model with biomechanical characteristics and probe the biomechanics of impact m exilla injuries. Methods In one case with no dentognath, mul ti-lay spiral CT scanning was used for from upper eyebrow to inferior border of madible, followed by three-dimensional image reconstruction and data transform ation. By using software Nastran and self- made procedure, impact injury of fro ntal maxilla was simulated, which was three-dimensional finite element biomedic al model of maxilla. The stress changes at various regions of maxilla were analy zed. Results When the stress point was placed at the maxilla , the stress would conduct from maxilla, pterygoid process and zygomatic to basi temporal part and affect temporomandibular joint, which caused significant stres s changes in the condylar process and neck of the condylar process and led to st ress aggregation in the region with suddenly decreased transverse area of bone. The impact wave conducted backwards in a gradient fashion and aggregated at the atlantooccipital articulation. Conclusions The stress changes caused by impact wave may aggregate at the bone suture and bone joint, result in change or destruction of conduction and form strong stress gradient leading to fractures. Compression injury is the main destruction at the impact site and ten sion injury dominated at the back of the impact site and condylar process, as ma y be one of biomechanical mechanisms of impact injury in theory.