老年患者人工股骨头置换的三维有限元分析

Finite element analysis of arthroplasty for unstable femoral intertrochanteric fractures in senile people

摘要:

目的 对人工股骨头置换治疗的老年股骨转子间不稳定骨折有限元模型进行生物力学分析。方法 对1 名健康老年男性志愿者左侧股骨行螺旋CT 断层扫描后将数据导入Mimics14.0 软件得到股骨实体，获得左侧股骨转子间不稳定骨折模型。根据AML 生物型假体及Muller 骨水泥假体的设计参数，制作AML 普通柄、加长柄及骨水泥柄模型，并植入骨折模型中模拟3 种不同材料的人工股骨头置换术。将人工股骨头置换模型与正常股骨模型导入Ansys13.0 软件中，对各部分材料赋值后加载负荷并作应力分析。结果 正常股骨自近端至远端不断增加，并于中下段达到峰值。人工股骨头置换后并未改变股骨总体的应力趋势，同样是由近端到远端逐渐增加，应力集中部位为全长股骨中段，但股骨近端的受力小于正常股骨，同时股骨上最大等效应力增加。3 种假体受力集中部位均为骨髓腔峡部与假体连接处，假体的最大等效应力相近；3 种假体对股骨受力的影响趋势相同，但加长柄对股骨下端应力的改变小于普通柄，股骨的最大等效应力由高到低依次为加长柄、普通柄和骨水泥柄。结论 人工股骨头置换术用于Tronzo-Evans IV 型股骨转子间不稳定骨折可提高股骨的最大等效应力。

Abstract:

Objective To explore the biomechanical property of arthroplasty for unstable intertrochanteric fractures in the elderly through finite element analysis. Methods A healthy male volunteer was chosen and given spiral CT to his left femur. The 3D bone substance was obtained after the data were imported into Mimics 14.0. Then unstable intertrochanteric fracture model was obtained by the segmentation and other operation. According to the parameters of the prosthesis and the anatomical data of the femur, conventional type, lengthening type and cement prosthetic replacement models were obtained. The force situations were compared among the 3 prosthetic replacement models and normal femur model. Results The force situations were similar in both sides of the normal femur; the force was increased from proximal to distal femur and reached its peak in the middle and lower segment. The force distribution of the artificial femoral head replacement models was similar as the normal femur and the force peaks were located in the middle segment; the force of the proximal femur in the artificial femoral head replacement models was smaller than that in the normal femur, and the maximum equivalent stress on femur increased in the artificial hip prosthesis. The maximum equivalent stress on femur of the cement prosthetic replacement model (43.2 Mpa) was smaller than that of the conventional type (46.1 MPa) and the lengthening type (47.2 MPa) prosthetic replacement models. Conclusions The force distribution of artificial femoral head replacement models is similar to that of normal femur. It can provide stability in early postoperative period.