The Application Of MRI In The Closed Reduction Of Developmental Dysplasia Of The Hip

Objective:Discussed the risk factors affecting the result of closed reduction and imaging indications of reduction success or failure in early judgment by assess MRI data of developmental dysplasia of the hip（DDH）after closed reduction.Compared MRI data of the children with DDH before closed reduction to further explore the significance of these factors in evaluating the outcome of closed reduction.Methods:Collected DDH children who underwent closed reduction and external fixation with plaster trousers from June 2015 to September 2016 in Tianjin Hospital,total 85 children,103 hips.All children underwent MRI examination after closed reduction,using GE Discovery MR 750 3.0T superconducting MR body scanning equipment to inspect the both hip joints.Scanning plane and sequence including coronal PDWI,coronal T₂WI and axial PDWI.Measuring the cartilaginous acetabular head index（CAHI）to evaluate the result of closed reduction.when CAHI is less than80%,the closed reduction results are not satisfied,.All children were divided into two groups:closed reduction successful and closed reduction failure group.The value of BAI,CAI,CE angle and CCE angle of two groups were measured on coronal images respectively.Meanwhile,the performance of acetabular cartilage,labrum and round ligament in two groups were observed carefully.Using SPSS 23 software,choosed independent sample t test to compare BAI,CAI,CEA,CCEA and age in two groups,choosedχ² test to compare sex,laterality,high signal area in the acetabular cartilage on T₂WI,labrum hypertrophy and varus,round ligament hypertrophy in two groups.In 40 children who underwent MRI examination before closed reduction,selected the independent sample t test to compare the BAI,CAI,CE and CCE angle in two groups;selectedχ² test to compare the high signal area in acetabular cartilage on T₂WI,labrum hypertrophy and varus and round ligament in two groups.Results:Compared with two groups after closed reduction,the sex,the hip side,age,and the value of BAI and CAI were not statistically significant difference.The value of CEA and CCEA in the failure group were significantly smaller than those in the successful group（P<0.05）.At the same time,incidence of the high signal in the acetabulum cartilage on T₂WI,the hypertrophy of labrum,the extension and thickened of the round ligament of failure group were significantly more than those in the successful group（P<0.05）.From two groups preoperative data comparison,the value of BAI,CAI,CEA,CCEA and incidence of the high signal area in acetabular cartilage on T₂WI had no obvious differences;the number of labrum hypertrophy and varus,round ligament extended and hypertrophy in the successful group were significantly less than the failure group（P<0.05）.Conclusion:The value of CEA and CCEA decreased obviously,which highly indicates the outcome of closed reduction failure.The high signal area in the acetabular cartilage founded on T₂WI,labrum hypertrophy and varus,round ligament prolonged and hypertrophy are the important factors which prevent the closed reduction and cause the outcome of treatment failure.Early diagnosis has great significance and plays a vital role in determining the treatment plan and preventing the occurrence of complications.