Clinical Study Of Pathological Morphology Of Acetabular Dysplasia In Patients With Developmental Dysplasia Of The Hip

Developmental dysplasia of the hip includes a series of hip dysplasia of the children:hip joint instability of neonates,subluxation,dislocation and acetabular dysplasia。Acetabular dysplasia,dysplasia of the femoral head,eccentric contraposition of the femoral head and acetabulum,alteration of the proximal femur, are the main bony pathological changes of DDH. Among them,acetabular dysplasia is the most foundational change. Controversy still exists about whether acetabular dysplasia is the congenital malformation of acetabulum, or is it the secondary change of acetabular development due to the physiological and biomechanical change after the hip dislocation. But in fact every child patient with DDH has acetabular dysplasia with varying degree. The study is to evaluate the pathomorphology of acetabulum in DDH patients using pelvic X-ray imaging and three-dimensional computed tomography imaging.MethodsFrom January 2008 to October 2009, we have accepted DDH children who have anterioposterior X-ray imaging data aging 0-5 yeas old,amounting to 152 cases. Acetabular index is measured on anterioposterior pelvic X-ray imaging using digital measuring software. The measurements are input to computer and analyzed by SPSS11.5 analytical software. There are 72 patients with complete three-dimensional computed tomography images, and these patients are further classified three subgroups:0-1.5 years old,1.5-3 years old, and 3-5 years old. We observed the morphology of acetabulum,type of acetabular defect. Some quantitative parameters were employed to evaluate the acetabulum including anterior acetabular index, posterior acetabular index and axial acetabular index of axial plane. 152 patients were categorized seven groups according their ages:0-6 months,6 months-1 years old,1-1.5 years old,1.5-2 years old,2-3 years old,3-4 years old and 4-5 years old. Acetabular index in the affected sides is seen Table 1.The AI has no significance statistically when compared between these groups. Acetabular index in the unaffected sides is seen Table 2,it is evident that AⅠdeclines as age increases.The AⅠhas significance statistically when compared between these unaffected side groups.The constituent ratio of the AⅠbetween different age groups has no significance statistically.By three-dimensional computed tomography of 93 hips, three types of acetabular dysplasia were demonstrated in the investigation:①A1,abnormal direction of acetabulum; (2)A2,limited dysplasia of lateral-superior acetabulum;③A3,global dysplasia of lateral acetabulum.The anterior acetabular index, posterior acetabular index and axial acetabular index of the affected side are larger than the unaffected sides of the same age group. But there is no significance statistically. Between the different age groups, there is no significance statistically when comparing the anterior acetabular index, posterior acetabular index, and axial acetabular index of the affected sides.ConclusionThe shape and degree of acetabular dysplasia differ in DDH. And there is no direct correlation between acetabular dysplasia and age. Acetabular dysplasia may be a congenital malformation.