The Value Of MRI Anterior Cartilaginous Acetabulum-Head-index To Evaluate Hip Function After Treatment Of Development Dysplasia Of The Hip

ObjectiveTo evaluate the feasibility of high resolution MRI for the measurement of anterior cartilaginous acetabulum-head-index(A-CAHI)and the diagnostic value of A-CAHI combined with lateral cartilaginous acetabulum-head-index(L-CAHI)for hip clinical function after treatment in developmental dysplasia of the hip(DDH).Materials and MethodsSixty-one patients with treated DDH for 3 years were recruited,all imaged with conventional MRI and high resolution PDWI of unilateral hip joint in oblique sagittal view.92 hips were divided into satisfactory clinical function group after treated(McKay rating excellent or good,46 hips)and unsatisfactory clinical function group(McKay rating fair or poor,46 hips)by pediatric orthopaedic specialists.A-CAHI and L-CAHI were measured respectively on high-resolution oblique sagittal PDWI and conventional coronal T1-weighted MR images.AHI was also measured on anteroposterior hip radiographs.All of the measurements were performed independently by two radiologists at different times.The measurement of A-CAHI was repeated 2 weeks later by one of the radiologists.Intraclass correlation coefficient was calculated for A-CAHI measurement.Mann-Whitney U test was used to compare the difference of A-CAHI and L-CAHI between two groups.The diagnostic value using A-CAHI,L-CAHI,AHI or A-CAHI combined with L-CAHI for unsatisfactory clinical function were investigated by the ROC curve.This study had been approved by our ethics committee.ResultsTotally 61 hip developmental dysplasia patients were examined,and totally 92 affected hips with developmental dysplasia were confirmed by follow-up.The mean inter-observer and intra-observer agreements were high for A-CAHI(ICC=0.997,0.976,respectively;P<0.05).The mean values of A-CAHI and L-CAHI were significantly higher in satisfactory clinical function group after treated compared with the unsatisfactory clinical function group(A-CAHI:86.41%±5.48%vs.70.00%±9.60%;L-CAHI:81.62%±3.69%vs.70.30%±6.90%;P<0.05 for all).A-CAHI combined with L-CAHI had the significant highest diagnostic accuracy compared with A-CAHI,L-CAHI,and AHI(AUC:0.994 vs.0.969/0.968/0.861,respectively;P<0.05 for all),and the sensitivity and specificity for the diagnosis of prognosis were 95.7%and 97.8%,respectively.A-CAHI and L-CAHI also had high predictive accuracy respectively,and the diagnostic threshold were 79.12%and 77.26%respectively,but the value of them were found to be statistically insignificant(AUC:0.969 vs.0.968;P>0.05).ConclusionHigh resolution MRI provides a precise,reliable and reproducible method of measuring A-CAHI.A-CAHI combined with L-CAHI was found to have the highest diagnostic accuracy for hip clinical function in the treated DDH and also can be a useful supplementary tool for the conventional imaging assessment.