头颈直径比与假体安装参数对髋关节活动度影响的计算机模拟研究

观察不同头颈直径比股骨假体全髋置换中,髋关节假体安装参数对髋关节活动度的影响,并探讨杯与颈前倾角优化组合。建立全髋关节假体三维可视化计算机模型,计算满足两组不同髋关节活动度下,髋臼外展角每变化5°时相应的髋臼前倾角安装角度,并在以髋臼外展角为横坐标,髋臼前倾角为纵坐标的坐标系上描点、连线画图,并对数据进行分析。实验显示,颈干角135°,髋关节一般标准和严格标准活动度,髋臼杯前倾角(Y)与股骨颈假体前倾角(X)的关系分别为Y1=-0.728X1+40.916,Y2=-0.7384 X2+46.456;允许的最小髋臼外展角(OImin)和头颈直径比(GR)的关系分别为OImin’1=254.27GR 1-3.172,OImin’2=230.58GR 2-2.519。髋关节活动度和髋臼安装角度安全范围随着头颈直径比增大而增大;髋关节活动度要求越高,髋臼安装角度安全范围越小。可允许的最小髋臼外展角随着头颈直径比的增大而变小。髋臼前倾角与股骨颈前倾角呈负相关。

Simulation Study on Influence of Orientation Parameter of Total Hip Components on the Range of Motion of Hip at Different Head/Neck Ratios Using Computer-Assisted Model

In this study a simulation model was proposed to examine the influence of orientation parameter of total hip components on the range of hip motion and obtain optimum combination of cup and neck anteversions in total hip arthroplasty at different general head/neck ratios(GR).A three-dimensional generic parametric and kinematic simulation module of total hip arthroplasty(THA) was developed.The corresponding operative anteversion(OA) of the cup was related to the operative inclination(OI) of the cup which every 5° was calculated,and described using dots and lines in a coordinate system in which OI of acetabular cup was horizontal ordinate and OA of acetabular cup was vertical ordinate.The results showed that when CCD-angle was 135°,the optimum relationship between OA of acetabular(Y)and FA of normal criteria and severe criteria(X)could be estimated by the formula: Y1=0.728X1+40.916(R2=0.999 9)and Y2=-0.738 4X2+46.456(R2=0.999 9)respectively,and the minimum allowable operative inclination(OImin) of acetabular should be more than 254.27GR-3.172(R2 = 0.991 7)and 230.58GR-2.519(R2 = 0.993 5)respectively.Large GR greatly increased the range of motion of the hip and the size of cup safe-zone.The more severe of the hip motion,the smaller size of the cup safe-zone,but could be retrieve by increasing the GR.The minimum allowable operative inclination(OImin) of acetabular was largely reduced with an increasing GR.The OA was negative with the femoral anteversion(FA).