应用三维有限元分析探讨髓芯减压术后产生的空洞对股骨头应力的影响

目的探讨股骨头缺血性坏死髓芯减压术造成的空洞形状、大小及与软骨下骨板距离对股骨头应力集中的影响。方法取成年男性正常股骨标本一具，经层厚2．0mm的螺旋CT扫描得各断面图象，输入计算机识别和提取股骨轮廓并行三维重建，导人ANSYS9．0进行前处理。按生理状态下股骨力载荷的三维空间分布，施加髋关节反力700N，外展肌力300N，髂腰肌力188N，和股外侧肌力292N。结果应力集中系数，以方孔为最大，角部倒圆方孔次之，圆孔最小。本组中，方孔与圆孔比较，应力集中最大增加可达80％；角部倒圆方孔与圆孔比较，应力集中最大增加可达30％。结论在空洞形状、空洞大小及空洞与软骨下骨板距离这三个因素中，空洞形状对应力集中的影响最大。髓芯减压术造成的空洞轮廓应以平缓曲线过渡，避免出现尖角。

Effect of the holes following core decompression on the stress of femora head:a 3D finite element analysis

Objective To explore the influence of shape and size of the holes following core decompression and the distance between hole and subchondral plate on stress concentration of femora head.Methods A normal femur specimen was chosen from a male adult and CT scanning was conducted by 2 mm interval to get the images of cross sections. The images were then inputted into computer to get contour of femur and rebuild 3D model. The pretreatment was managed by ANSYS 9.0. The hip joint reaction force of 700 N, the abductor muscle force of 300 N, the Iliopsoas force of 188 N and the vastus lateralis muscle force of 292 N were applied according to the Three-dimensional space distribution of femur force under physiological state. Results The sequence of holes （from small to large） in magnitude of stress concentration coefficient, were square hole, fillet hole and round hole. The stress concentration coefficient of square hole, as compared with round hole, would increase by 80% at its height reach, while the coefficient of fillet hole, as compared with round hole, would increase by 30% at its hightest reach.Conclusions The influence of the shape of hole upon the magnitude of stress concentration coefficient was the largest. The contour of hole following core decompression should be gentle and avoid abrupt angle.