正常的髋关节是一个杵臼关节,它的稳定性依赖于臼的形态、方向、臼对头的包含,以及髋关节周围的肌肉、V 型韧带、圆韧带和关节囊。而臼对头的包含不是一成不变的,新生儿髋臼相对浅,股骨头呈半球形,臼对头的包含很大程度上依赖软骨性的臼盂,随着婴儿的生长发育,臼的深度相对加深,股骨头渐渐发育至近似于球的三分之二,这个过程要到3岁以后才能完成。因此,从 X 线片上测量髋臼指数,随着年龄的增长,髋臼指数减少就是这个道理。 The normal hip joint is a mortisei joint whose stability depends on the morphology, orientation, acetabulum of the acetabulum, the muscles around the hip joint, the V-shaped ligament, the round ligament and the joint capsule. The acetabular inclusion is not static, neonatal relatively shallow acetabulum, femoral head was hemispherical, acetabular contralateral depends largely on the cartilage of the mortar, with the baby’s growth and development, the depth of the mortar is relatively deepened, Femoral head gradually developed to approximately two-thirds of the ball, the process to be completed after 3 years of age. Therefore, measuring the acetabular index from the X-ray film, with age, the acetabular index decreased is the truth.