髋臼内陷技术对成人DDH全髋关节置换术髋臼杯生物力学影响的有限元分析

目的 探讨髋臼内陷技术对成人发育性髋关节发育不良（developmental dysplasia of the hip,DDH）髋关节置换术后髋臼假体的生物力学效应。方法 获取1名成人单侧DDH患者双侧髋关节CT图像数据,进一步构建患侧半骨盆有限元模型,在此基础上,建立臼杯不同内陷水平的有限元模型,对比分析原位组和不同水平内移组之间的生物力学差异。结果 在模拟拔出试验中,原位组最大抗拔出载荷强度为1 166 N;相比原位组,4 mm和8 mm内移组抗拔出载荷强度分别增加了45.8%和57.1%;原位组髋臼假体在步态周期站立位相载荷工况下的臼杯-骨界面最大微动为166.4 μm,内移4 mm及8 mm组相对原位组分别减少了46.2%和62.1%。对于臼杯植入后髋臼周围即刻应力分布,不同组别之间的差异并不显著;而在步态周期站立位相载荷工况下,原位组髋臼周围平均应力及峰值应力均最小,平均应力随内移程度的增加而增大,内移4 mm组峰值应力最高。结论 相较原位植入假体,髋臼内陷技术可以提高假体初始稳定性,稳定性和内移程度成正比。但内移程度不足导致骨覆盖面积不足时,臼杯-骨界面边缘应力显著增加,可能会导致假体相关并发症风险的升高。

Effects of Medial Protrusio Technique of Total Hip Arthroplasty on Acetabular Cup in Adult Patient with Developmental Dysplasia of the Hip: A Finite Element Analysis

Objective To investigate the biomechanical effects of the medial protrusio technique on the acetabular cup in adult patients with developmental hip (DDH) after total hip arthroplasty. Methods The CT scanning data of bilateral hips from an adult patient with unilateral DDH were obtained further to develop a finite element model of the affected hemipelvis. The medial protrusio technique with various levels of medial protrusio was simulated, and the biomechanical differences between the medial protrusio and non-protrusio groups were evaluated. Results In the simulated pull-out test, the maximum anti-pull-out load strength of the non-protrusio group was 1 166 N. Compared with the non-protrusio group, the anti-pull-out load strength of the 4 mm and 8 mm medial protrusio groups increased by 45.8% and 57.1%, respectively. The peak micromotion at the cup-bone interface for the non-protrusio group was 166.4 μm in the standing phase of the gait cycle, and that of the 4 mm and 8 mm medial protrusio groups was decreased by 46.2% and 62.1%, respectively. Regarding the immediate stress distributions of periacetabular bone tissues following cup implantation, the differences between the groups were not significant. Under the loading condition of the standing phase, the non-protrusio group yielded the lowest average and peak stresses. The average stress increased with the level of medial protrusio, and the highest peak stress was observed in the 4 mm medial protrusio group. Conclusions The medial protrusio technique can improve the initial stability of the acetabular cup, and the initial stability is positively proportional to the protrusio level. However, owing to the concentration of marginal stress at the cup-bone interface, a minor medial protrusio cup with insufficient bone coverage might increase the risk of various prosthesis-related complications.