全髋关节置换术中髋臼假体位相的安全范围及杯颈前倾角的优化组合

The cup safe-zone and optimum combination of the acetabular and femoral anteversions in total hip arthroplasty

目的 探讨全髋关节置换术（THA）中髋臼杯的安全范围及杯颈前倾角的优化组合方法. 方法 建立THA三维可视化模型,定义两种髋关节活动度标准：一般标准（髋关节屈曲≥110°、屈曲90°时内旋≥30°、后伸≥30°和中立位外旋≥40°而没有假体撞击）和严格标准（髋关节屈曲≥120°、屈曲90°时内旋≥45°、后伸≥30°和中立位外旋≥40°而没有假体撞击）.头颈比变化范围为2.00 ～2.92,股骨假体前倾角变化范围为0～30°,髋臼假体外展角变化范围为10°～60°,髋臼前倾角变化范围为0 ～ 70°,计算满足髋关节两组活动标准、臼杯外展角每变化5°相应的髋臼假体前倾角的安装参数.结果 严格标准下的安全范围较一般标准小,两种标准下的髋臼杯安全范围面积随着头颈比增大而增大.当颈干角为130°时,一般标准和严格标准下髋臼杯前倾角（Y）与股骨假体前倾角（X）的关系分别为Y1=-0.840X1＋38.41,Y2=- 1.007 X2 ＋47.46；允许的最小髋臼外展角（OImin）和头颈比（GR）的关系分别为OImin＇1=168.13 GR1-2.504,OImin＇2=213.79 GR2-2.272.当颈干角从135°移向130°时,杯安全范围移向杯前倾角较小的区域,面积也有所减小.结论 THA中可以通过增大头颈比来扩大臼杯安放的安全范围.允许的最小髋臼外展角随着头颈比增大而变小,杯前倾角与股骨颈前倾角呈负相关.股骨颈前倾角的增大和颈干角的变小均使得杯安全范围移向杯前倾角较小的区域.

Objective To determine the cup safe-zone and the optimum combination of cup and neck anteversions in total hip arthroplasty（THA）. Methods A three-dimensional generic parametric and kinematic simulation module of THA was developed.Ordinary and strict criteria were defined regarding hip ROM as follows：normal criteria：flexion ≥ 110°,intorsion ≥ 30° at 90° flexion,backward extension ≥ 30°and extorsion ≥40° at the neutral position without prosthetic impingement; strict criteria：flexion ≥ 120°,intorsion≥45°at 90° flexion,backward extension ≥30° and extoraion ≥40° at the neutral position without prosthetic impingement.The changes in die head-neck ratio （GR）,die femoral neck anteversion （F.A）,the operative inclination （OI） and anteversion（OA） of the cup component ranged respectively from 2.00 to 2.92,0 to 30°,10° to 60° and 0 to 70°.For the 2 collodiaphyseal angles（CCD） of 130° and 135°,the corresponding OA related to the OI at every 5° was calculated. Results The size of cup safe-zone by the strict criteria is smaller than that by the normal criteria,and the sizes are both increased when a larger GR is chosen.When the CCD-angle is 130°,the optimum relationships between acetabular OA and FA by the normal and strict criteria can be estimated with the formula： Y1 =-0.840X1 ＋ 38.41 and Y2 =-1.007X2 ＋47.46 respectively. The minimum allowable operative inclination （O1min） of the acetabulum should be more than 168.13 GR1-2.504 and 213.79 GR2-2.272 respectively.When the CCD changes from 135° to 130°,the cup safe-zone moves to an arca of a smaller OA and shrinks slightly in area. Conclusions Although the more strict the criteria regarding hip ROM,the smaller the cup safe-zone,the reduced safe-zone can be retrieved by increasing the GR.The OImin is largely reduced with an increasing GR The OA is negatively associated with the FA.Increase in neck anteversion and decrease in CCD can move the cup safe-zone towards an area of a smaller OA.