股骨颈骨折内固定方式的有限元分析

目的　研究股骨颈骨折不同内固定方式对骨折端应力分布规律的影响 ,寻找符合生物力学原理的最佳内固定方式 ,为临床应用提供理论依据。方法　在Pro/ENGINEER中建立股骨近端实体模型 ,导入ANSYS 5 7建立有限元模型。在单钉固定的情况下对Pauwel,s角为 5 0°的经颈型骨折模型施加载荷 ,通过不同固定角度时的力学特征综合评价固定效果 ,并找出最佳固定角度 ;对该最佳固定角度下多钉不同固定方式进行计算和分析 ,评价不同固定方式的优劣。结果　单钉固定时当固定角度为 5 0°时 ,各参数同时达到最小值 ,说明以该角度固定可取得最佳的力学效果 ;如采用多钉固定 ,两钉横放效果最差 ,两钉竖放抗扭性较差 ,两钉斜放和三钉固定时力学环境好。从临床实用角度综合分析 ,单钉固定力学效果较好 ,且操作简单。结论　不同固定角度和螺钉组合方式对骨折面的力学环境有重要影响。

FEA of Different Internal Fixations for Femoral Neck Fractures

Objective To investigate the effects of stress changes by using different internal fixation methods in femoral neck fracture in order to find out the most optimal one with sound biomechanical principles before clinical application. Methods Pro/ENGINEER software was used to create a solid model, which was subsequently input into ANSYS 5.7 to establish Finite Element Analysis (FEA) model. A femoral neck fracture with Pauwel's angle of 50° and fixed with a single screw was used to find out the best fixation angle with sound biomechanical principle. Different internal fixations with 2 or 3 screws were then used to find the one with best fixation quality at this best fixation angle. Results When fixation was made for single screw at 50°, all evaluated parameters reached their lowest value, which suggested the optimal screw fixation angle. When 2 or 3 screws were used for fixation, the fixation with two level ones revealed overall the most inferior mechanical stability; two vertically placed screws for fixation showed the lowest anti-torsional property; the fixation with two obliquely inserted screws or combination of three screws provided better mechanical stability. After balancing many factors and from the clinically practical point of view, Single screw fixation was found to be technically simple and also provided reasonable good fixation effects. Conclusion Results of FEA analysis suggested that the difference in screw fixation angles and in way of combined use of screws might have important influence on biomechanical stability of femoral neck fracture fixation.