不同髋臼杯前倾位置和球头假体大小对全髋关节置换术后后方稳定性的影响

目的探讨髋臼杯的前倾位置与球头大小对全髋关节置换（THA）术后后方稳定性的影响。方法利用计算机导航技术在假骨上模拟THA术后，不同髋臼杯前倾位置和不同球头大小在屈髋90°、内收0°和内收30°时髋关节内旋到引起脱位的角度进行测量和比较发生后脱位时的角度差异。结果在髋臼杯外展45°、前倾0°、5°、10°、15°时，28mm和36mm球头在屈髋90°内收0°和30°睛况下内旋至脱位的角度有明显差别（均为P〈0．05），36mm球头可有更大的内旋角度，稳定性优于28mm球头。但当髋臼杯前倾20°时28mm与36mm球头内旋至脱位的角度间的差异无统计学意义（P〉0．05），内收30°时比内收0°时髋关节内旋至脱位的角度减小。关节稳定性随髋臼杯前倾减小而下降。髋臼杯前倾0°和髋关节内收30°时，28mm球头在外旋位时就可发生脱位。结论髋臼杯前倾角度增加可增加THA术后关节的稳定性，大球头的稳定性优于小球头，前倾达到某一角度时，大球头和小球头间的后方稳定性无差别。

The effects of acetabular component position and hip ball diameter on posterior stability after total hip replacement

Objective To study the effects of acetabular component position and hip ball diameter on the posterior stability of the hip joint after total hip replacement.Methods Computer navigation system and synthetic bone model were used to simulate the motion of hip after total hip replacement. The hip was flexed to 90 degree and was adducted 0 and 30 degree as indicated by the computer navigation, after then it was progressively internally rotated until the hip was dislocated. The degree of internal rotation when the hip was dislocation was recorded.Results When the acetabular component abduction was 45 degree and anteversion were 0, 5, 10, 15 degrees, and the hip was flexed to 90 degree and adducted to 0 and 30 degrees, there was significant difference between 28 mm and 36 mm hip balls in the degrees of internal rotation when the hip was dislocated （P〈0.05）. 36 mm diameter hip ball was significantly better in stability. The degree of internal rotation when the hip dislocated was less when the hip was adducted 30 degree compared to 0 degree. The stability was diminished with less acetabular component anteversion. With 0 degree anteversion and the hip adducted to 30 degree, a 28 mm diameter hip ball would lead to dislocation even if the hip was in external rotation. Conclusions The increasing anteversion of acetabular component can increase the stability of total hip replacement. Large hip ball is more stable than small hip ball. However, when anteversion of acetabular component is sufficient, there is no difference in stability between large and small hip balls.