以三维有限元法分析髁突横断骨折和纵行骨折的生物学应力

Biological stress analysis of condylar transverse fracture and longitudinal fracture using three-dimensional finite element method

背景:当下颌骨在受到撞击时常常发生髁突和髁突颈的骨折,临床上常见髁突横断骨折和纵行骨折。为什么撞击方式不同就导致不同类型的骨折?目的:应用有限元模拟撞击相的方法,分析下颌骨髁突受到撞击时应力、应变的变化,探索髁突横断骨折和纵行骨折的生物力学机制。设计、时间及地点:单一样本实验,2007年在清华大学汽车安全与节能国家重点实验室完成。参试者:将一下颌骨发育正常的成年女性行CT扫描,CT机原始数据下载,建立下颌骨三维有限元模型。方法:在边界约束条件完全相同的情况下,以3.6m/s相同速度模拟下颌骨颏部正中以不同角度撞击正前方刚体,首先是水平方向(0°),然后分别是顺时钟方向10°,20°,30°,40°,50°,60°依次模拟撞击。主要观察指标:不同的角度撞击时下颌骨各部分的应力和应变变化。结果:以不同角度撞击时,除了在撞击点出现损伤(骨折)外,在髁突出现两种不同类型的损伤(骨折)。水平撞击时髁突出现横断骨折垂直,斜向下撞击约在顺时针40°时开始出现纵行骨折倾向。结论:在髁突间接撞击损伤中,除其解剖特点外,撞击方向不同是导致不同类型损伤(骨折)的一个相对主要因素。

BACKGROUND： When mandible is impacted it usually occurs condylar fracture and condylar neck fracture, including transverse fracture and longitudinal fracture. Why will the different impact style result in different type fracture？ OBJECTIVE： To analyze the changes of stress and strain when the mandibular condyle with three-dimensional finite element method and to investigate biomechanical mechanism of condylar transverse fracture and longitudinal fracture. DESIGN, TIME AND SETTING： The single sample experiment was carried out at the State Key Laboratory of Automobile Safety and Energy, Tsinghua University in 2007. PARTICIPANTS： An adult female with a well-developed mandible was performed CT scanning and the CT original data were downloaded to establish three-dimensional finite element model of mandible. METHODS： Median mental region of mandible was imitated to impact anterior rigid body at 3.6 m/s from different angles under the same boundary constraint condition, first from horizontal direction （0 degree）, then from 10, 20, 30, 40, 50, 60 degrees clockwise in turn. MAIN OUTCOME MEASURES： The stress and stress changes of mandible when impacted from different angles. RESULTS： When the mandible impacted anterior rigid body from different angles, it appeared two different kinds of fractures at the condyle process besides fracture at the impact site. The condyle process appeared transverse fracture when the mandible impacted anterior rigid body from horizontal direction, and it began to appear longitudinal fracture tendency when the mandible impacted anterior rigid body from 40 degrees clockwise. CONCLUSION： In the indirect impact injury of condyle process, in addition to anatomic characteristics, the impact direction is a relative major factor that result in distinguished types of condyle fracture.