跟骨三维有限元模型的建立及其骨折发生机制

Three-dimensional finite element analysis of calcaneal fractures

目的:建立跟骨三维有限元模型,探讨跟骨骨折发生机制。方法:通过扫描正常人跟骨螺旋CT,精确模拟边界条件,并运用Sap93计算软件运算建立跟骨有限元模型,模型由1959个节点,1496个单元组成。在跟骨有限元模型上模拟踝关节在中立位和背伸20°时的状况后对模型施以500N的垂直轴向载荷,观察模型应力分布和位移情况。结果:跟骨在踝关节中立位时通过跟距外侧的关节面,并且由内后斜向前外方向的跟骨处遭受应力最大。背伸20°受力时除上述位置遭受应力最大外,从跟骨体部走向后距关节面与跟腱之间的部位遭受应力也比较大。结论:高处坠落踝关节中立位时跟骨骨折的发生将从跟距关节面的外侧向内后方向走行;当坠落时踝关节处于背伸位时除产生上述骨折线外,跟骨体部走向后距关节面方向也将发生骨折,同时跟腱附着点附近也会形成撕脱性骨折。

Objective：To establish the three-dimensional finite element model of calcaneus,and to discuss mechanism of calcaneal fracture. Methods：The calcaneus of normal person was scanned with spinal CT,and the finite element model was established with the Sap 93 software. The node and element number of this model was 1 959 and 1 496 respectively. After establishing the finite element model of the calcaneus,the axial load of 500 N was applied on the model in neutral position and back stretches 20° position. The stress distribution and the displacement of the models were observed. Results：The fracture line passed through the lateral articular facet of talocalcaneal joint when the ankle joint was in neutral position,and the stress distribution was maximal at calcaneus from posteromedial to anterolateral aspect. In addition,the stress distribution was maximal from calcaneus to position between posterior talar articular surface and calcaneal tendon when the ankle joint was in back stretch position of 20 degree. Conclusion：When falling down,the fracture line will pass through the facet of talocalcaneal joint from lateral to posteromedial side if the ankle joint was in neutral position; and the line will through pass the calcaneus body to post spinula joint,as well as avulsion fracture of calcaneal tendon occurred if the ankle joint was in back stretch position of 20 degree.