MRI study of the infantile developmental dislocation of the hip / 实用放射学杂志

ABSTRACT

Objective To investigate the diagnostic value of MRI in the infantile developmental dislocation of the hip.Methods Forty-five cases of preoperative hip MRI data of DDH (patient group)and 40 cases of normal hip (control group)MRI data were retrospectively analyzed.Three types were classified according to the standard of Dunn.Then the bony acetabular index (BAI),cartilaginous acetabular index (CAI)were measured on coronal MRI and all the intra-articular structures (articular cartilage,labrum, teres ligament and iliopsoas)in the acetabulum that impeded the reduction of the femoral head were observed.Results There were normal hips (80 hips)and dislocated hips (73 hips).In dislocated hips typeⅠ (30 hips),typeⅡ (20 hips),and typeⅢ (23 hips) were found.The values of BAI were (26.13±2.19)°and (35.87±4.42)°,CAI (13.84±1.07)°and (21.92±4.70)°for patient group and control group.The values of BAI were (31.80±1.74)°,(37.80±3.40)°and (39.17±4.11)°,CAI (17.20±2.68)°,(20.91±2.02)°and (27.50±2.78)°for the typesⅠ,Ⅱ,Ⅲ respectively.Differences of BAI and CAI between patient group and control group were showed (t=-11.048 and -9.188,P =0.000).Statistically significants were found among the typeⅠ,Ⅱ,Ⅲ(F=22.159 and 47.241,P =0.000).There were linear correlations for patient group ,control group,and the typeⅠ,Ⅱ,Ⅲ (r= 0.964,0.844,0.953,0.931 and 0.870,P =0.000).Some pathological changes such as varus labrum,thick teres ligament,iliopsoas spasm,articular cartilage hyperplasia,fat hyperplasia,joint effusion were observed in the type Ⅱand Ⅲ.Conclusion MRI is not only used for measuring the values of BAI and CAI,and a linear correlation among all kinds of DDH,but also some factors hindering the reduction of the femoral head can be found clearly.It can provide an important reference basis for the diagnosis and treatment of DDH.