利用有限元分析技术探讨后踝骨折的治疗方案

Optimization for Posterior Malleolus Fracture Treatment with Finite Element Analysis Method

目的通过踝关节三维有限元模型,研究静止站立位后踝骨折后胫距关节面的应力变化及位移趋势,为后踝骨折的治疗提供理论依据。方法以一套正常人体站立位踝关节CT图像为原始数据,应用有限元建模技术,建立带有关节软骨的踝关节三维有限元模型,对模型的有效性进行验证。通过对后踝关节面进行分区、切割,模拟计算后踝不同骨折范围条件下施加正常应力时的关节软骨接触面积、最大接触应力、平均接触应力、最大位移等参数。结果随着骨折范围的增加,胫骨软骨接触面积呈逐渐减小趋势,胫骨软骨的平均接触应力值逐渐增大,胫骨相对位移增加。胫距关节的应力区主要集中在踝穴的外侧及前外侧,当后踝骨折面积超过1/3时,关节负重区面积明显缩小,关节位移趋势增加。结论后踝骨折面积超过1/3时,关节接触面积明显减小,应力变化明显增加,关节位移趋势增加,预后不佳,具有手术复位固定的指征。

Objective To provide the theoretical basis for the treatment of posterior malleolus fracture by investigate the stress variation and displacement trend of tibial astragaloid joint at still stand position with 3D finite element model of ankle, which has suffered the posterior malleolus fracture. Methods The 3D finite element model of ankle with cartilage was established with a set of the normal standing human ankle CT images as primitive data. The model was validated and after the CT image of tibial astragaloid joint was zoned and cut into different range fracture in normal stress loading cases, we simulated the articular cartilage contact area, max contact press, mean contact press and max displacement. Results With the increase of the fracture area, the contact area of tibial articular cartilage decreased, the contact stress of the joint and relative displacement increased gradually. As the fracture area exceeded third, the joint load area decreased obviously and the joint displacement trend increased. Conclusions As the fracture area is more than third, the articular cartilage contact area and contact stress change obviously, which results in bad prognosis and in need of surgical operation.