单侧外固定架治疗跟骨SandersⅡ型骨折的有限元分析

Finite element analysis of external fixator for SandersⅡcalcaneus fracture

目的通过有限元分析评估单侧外固定架固定跟骨SandersⅡ型骨折的牢靠程度及应力分布情况。方法通过CT扫描获得健康成年男性右侧足踝部骨骼及软组织数据,利用Mimics、Patran、Abaqus等有限元分析软件建立单侧外固定架固定治疗跟骨SandersⅡ型骨折模型。在模拟下肢非负重状态下跟骨受到跟腱的最大拉应力时,骨折块之间的位移程度及外固定架应力分布情况。结果骨折块之间向踝关节内侧、后侧、上方的相对位移分别为0.027 2 mm、0.095 1 mm、0.139 8 mm;骨折块之间最大位移为0.175 3 mm,未达到跟骨关节内骨折手术指征中骨折线分离或移位>1 mm的标准;最大应力分布区域在外固定钉上,最大应力值为37.06 MPa,小于外固定钉屈服强度225 MPa。结论单侧外固定架固定治疗跟骨SandersⅡ型骨折是一种可靠的固定方式。

Objective To evaluate firm level and stress distribution of unilatera external fixator for Sanders Ⅱ calcaneus fracture by finite element analysis. Methods The data of right normal foot and ankle structure of normal adult male were collected through CT scans, and the Mimics software and Patran software were used to build the finite element models of external fixator for Sanders Ⅱ calcaneus fracture. The displacement and stress distribution of fractures with extenal fixator in the simulation of lower limb non-weight-bearing status, calcaneal tendon were subjected to the maximum tensile stress. Results The relative displacement between the fracture blocks to the medial, back, above the ankle were 0.027 2 mm, 0.095 1mm, and 0.139 8 mm respectively. The maximum relative displacement was 0.175 3 mm, which was less than separation or displacement of the fracture line 1 mm of the surgical indications of intra-articular cancaneal fractues. The maximum stress area was in the fixed nails, and the maximum stress value was 37.06 MPa, which was less than the external fixation nail yield strength 225 MPa. Conclusion It is a reliable fixation for unilateral extemal fixator of Sanders Ⅱ calcaneal fracture.