Objective To investigate the effect of cartilage acetabular ,glenoid labrum and acetabular tissue on closed reduction of developmental dysplasia of hip ( DDH ) by analyzing the outcomes of the ultrasound measurement on DDH before and after Pavik Harness treatment . Methods Graf method was used in ultrasound measurement before the treatment . Position of cartilaginous acetabulum and glenoid labrum and displacement direction of femoral head in 31 patients with hip dislocations ( type D ,type Ⅲ ,typeⅣ ,36 hips) were recorded . T he follow‐up testing with ultrasound measurement on the inside of the hip were performed after 1 －2 weeks of Pavik Harness treatment . M ediolateral dimension ,anteroposterior dimension and the area of maximum section of acetabular tissue were measured . Reduction effects were evaluated . Results T he success rate of reduction of dislocation hips with cartilaginous acetabulum on the head orientation was obviously higher than that on the foot orientation( P ＜0 .000 1) . T he success rate of reduction of dislocation hips with glenoid labrum on the head orientation was obviously higher than that on the foot orientation ( P ＝ 0 .001 6 ) . T here was a statistically significant difference in the success rate of different types of hip dislocation ( type D , type Ⅲ , type Ⅳ ) ( P＝ 0 .002 7 ) . T here were statistically significant differences in mediolateral dimension ,anteroposterior dimension and the area of maximum section of acetabular tissue between the reduction group and the group without dislocation ,the irreducible group and the group without dislocation ,the irreducible group and the reduction group ( P ＜ 0 .01) . Conclusions Ultrasonography is of great significance in the diagnosis and treatment of children with DDH . T he position of hip cartilaginous acetabulum and glenoid labrum ,types of hip dislocation and the volume of acetabular tissue have important effects on the success of the closed reduction .

Objective:To evaluate the feasibility of high resolution MRI for the measurement of anterior cartilaginous acetabulum-head-index (A-CAHI) and the value of A-CAHI for predicting hip clinical function after treatment in developmental dysplasia of the hip (DDH).Methods:The imaging data of 92 hips from 61 children with treated DDH were retrospectively reviewed in Shandong Medical Imaging Research Institute from January 2019 to January 2020. All children underwent conservative treatments or surgical interventions 3 years ago. Hip function after treatment was evaluated clinically based on the modified MacKay criteria. The hips were divided into satisfactory clinical function group (McKay rating excellent or good, n=46) and unsatisfactory group (McKay rating fair or poor, n=46). All patients were imaged with conventional MRI, high resolution fat suppressed proton density weighted image (FS-PDWI) of the unilateral hip joint in oblique sagittal view, and anteroposterior hip radiographs. A-CAHI and lateral cartilaginous acetabulum-head-index (L-CAHI) were measured respectively on high-resolution oblique sagittal PDWI and conventional coronal T 1WI. Acetabulum head index (AHI) was also measured on anteroposterior hip radiograph. Mann-Whitney U test or independent-samples t test was used to compare the difference of A-CAHI, L-CAHI and AHI between satisfactory and unsatisfactory clinical function 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. The area under the curve (AUC) and the Z statistic were used to compare diagnostic performance. Results:The values of A-CAHI, L-CAHI and AHI were significantly higher in satisfactory clinical function group compared with the unsatisfactory group ( Z=-7.746, -7.735, t=-7.199, all P<0.001).A-CAHI combined with L-CAHI had the significant highest diagnostic accuracy compared with A-CAHI, L-CAHI and AHI (AUC were 0.994, 0.969, 0.968, 0.861, respectively), with significant differences ( Z=1.975, 2.006, 3.553, P=0.048, 0.051,<0.001). The sensitivity and specificity of A-CAHI combined with L-CAHI for the diagnosis of prognosis were 95.7% and 97.8%, respectively. Conclusions:A-CAHI measured by high resolution MRI was found to have the highest diagnostic accuracy for prediction of hip clinical function in the treated DDH, and combined with L-CAHI can improve the diagnostic accuracy significantly.