臼杯假体高度对臼杯-骨界面应力应变影响的有限元分析

目的探究臼杯假体模拟植入Crowe Ⅱ/Ⅲ型DDH髋臼的不同高度时臼杯-骨界面间应力和应变分布特征。 方法基于3位Crowe Ⅱ/Ⅲ型DDH患者髋关节的CT扫描数据,利用计算机软件作髋臼三维建模,在距髋臼下缘连线垂直高度为15、21、30 mm处分别模拟植入臼杯模型,并转化为三维有限元网格模型,施加静力载荷,记录臼杯-骨界面的应力和应变数据,行配对t检验或Wilcoxon符号秩检验分析各组最大应力及应变的差异。 结果3组臼杯模型在距髋臼下缘连线垂直高度为21 mm处的最大应力值最小,分别为患者A 10.03 Mpa、患者B 17.67 Mpa和患者C 14.99 Mpa。在安装高度为15 mm和30 mm处,臼杯的最大应力值分别为患者A 20.64、12.03 Mpa,患者B 22.06、23.02 Mpa和患者C 34.72、17.88 Mpa。对15、21、30 mm处骨质、臼杯的最大应力及应变行两两配对检验显示各组差异无统计学意义(校正后P>0.0167)。不同安装高度下臼杯假体及假体周围骨组织应变量没有明显分布规律。 结论对于Crowe Ⅱ/Ⅲ型DDH患者行全髋关节置换术,适当上移臼杯旋转中心能减少臼杯假体最大应力。

Finite element analysis of effects of stress and strain on acetabular cup-bone interface at different heights

ObjectiveTo investigate the stress and strain feature at the acetabular cup-bone interface at different heights of the Crowes Ⅱ/Ⅲ DDH acetabular implant. MethodsThe hip CT scan data of three Crowe Ⅱ/Ⅲ DDH patients were used for acetabular three-dimensional model reconstruction, then the cup models were implanted at vertical distance of 15, 21, 30mm respectively from the inferior edge of the acetabulum. The model was transformed into a three-dimensional finite element mesh model, and applied a static load to record the stress and strain at the cup-bone interface. The differences of the stress and strain at the cup-bone interface were analyzed by paired-sample t test or Wilcoxon rank test. ResultsThe minimal value of maximal stress was appeared at the vertical height of 21 mm, patient A 10.03 Mpa, patient B 17.67 Mpa and patient C 14.99 Mpa. At the height of 15mm and 30mm, the maximal values of maximal stress of the cup were as follows: patient A 20.64 and 12.03 Mpa, patient B 22.06 and 23.02 Mpa, patient C 34.72 and 17.88 Mpa. Paired-samples t test revealed no significant difference in the stress and strain at the cup-bone interface(P>0.0167, P value was corrected). There was no specific pattern on the strain of the acetabulum and the bone tissue at different heights. ConclusionFor total hip arthroplasty in the patients with Crowe Ⅱ/Ⅲ DDH, the cup model implanted upward appropriately can decrease the maximal stress of the cup model.