Three-dimensional Radiographic Investigation On The Skeletal Abnormalities Of Developmental Dislocation Of Hip

Background: Developmental dislocation of the hip (DDH) is currently one of the common musculoskeletal disorders, which have severe impact on the growth and development of children, and their living quality as well. The DDH pathology includes the 3-D spatial abnormalities in bones, cartilaginous and soft tissues. Our previous knowledge about DDH mainly came from the 2-D radiographic examinations, which could not represent the 3-D pathology. This leads to the inappropriate diagnosis, decision-making for the treatment, and even outcome evaluation. Purposes: By means of 3DCT technique, we investigated the skeletal pathologies from acetabulum to femoral head in DDH for the assistance in surgical planning. Methods: 1. One hundred and forty-six patients with DDH had their hips examined with 3DCT preoperatively. The imaging study was performed to investigate the pathoanatomy of bony abnormalities in these cases. The acetabular index (AI) and femoral neck anteversion (FNA) were measured respectively for therecognition of the pathological typing. 2. Fifty-seven patients with DDH were examined by using 3DCT. We used 3DCT to demonstrate the whole acetabular growth circumstance and acetabular coverage by three-dimensional measurement of AI and centre-edge angles(CEAs). 3. Forty-one patients with DDH were studied to compare the whole acetabular growth circumstance and acetabular coverage by using 3DCT before and after the surgical treatment. 4. The system of Developmental Dislocation of Hip-Computer Aided Design(DDH-CAD) was developed to simulate the surgical treatment of DDH by applying the techniques of both medical visualization and computer-aided design. Results: 1. The skeletal abnormalities were revealed in DDH in terms of acetabulum, femoral head and congruous relationship between acetabulum and femoral head. The morphology of DDH in terms of AI and CEA is greatly different from that of control. Three types of acetabular dysplasia were demonstrated in our investigation: (1)AI, abnormal direction of acetabulum; (2)A2, limited dysplasia of lateral-superior acetabulum; (3)A3, global dysplasia of lateral acetabulum. 2. The 3DCT measurements can represent the whole acetabular growth circumstance and acetabular coverage. Mean value of normal AI at the lateral-superior rim was 19.6° with a 95% confidence interval of 14.3°-24.1°. Mean value of normal CEA at the lateral rim was 27° with a 95% confidence interval of 26.2°-27.9°. 3. There is no significant difference in AI and FNA between normal control and postoperative group.And there are significant difference in CEA between normal control and postoperative group. The values of CEA in DDH are...