Morphological characteristics of hips in children with developmental dislocation of the hip:three-dimensional reconstruction of computed tomography scan / 中国组织工程研究

ABSTRACT

BACKGROUND: The development of hip joint in children with developmental dislocation of the hip (DDH) has been evaluated by X-ray plain film, which mainly presents Shen Tong's line continuity and epiphyseal nucleus position. There is still a lack of quantitative and objective evaluation methods. OBJECTIVE: To evaluate the rotation center and dislocation degree in DDH children by using three-dimensional (3D) computed tomography (CT).METHODS: Preoperative 3D CT was performed for 16 unilateral DDH from December 2010 to December 2014 in Tongji Hospital of Huazhong University of Science and Technology, with 4 males and 12 females, at the mean age of (4.42±2.59) years. There were 10 cases on the left side and 6 cases on the right side. 3D digital models were constructed by analysis. The 3D coordinate system was established with reverse engineering software. In 3D coordinatesystem, using inverse solution method of sphere fitting engineering, the rotation center of the acetabulum, the rotationalcenter of the femoral head, and the radius of ossification were constructed. Ossific radius ratio and dislocation lengthwere calculated. RESULTS AND CONCLUSION: (1) The acetabulum has the same point as the rotation center with the head of femur,and no significant difference in X, Y, and Z coordinates was detected (Px > 0.05, Py > 0.05, Pz > 0.05). However, it is notthe same condition in ipsilateral acetabular rotation center and femoral head rotation center, showing significant differences (Px=0.052, Py 0.05). The ossific radius was (21.37±4.42) mm and (20.14±3.14) mm on the healthy and affected sides of the femoral head (P 0.05). (4) The dislocation length was 8.64-35.28 mm, mean (19.47±7.84) mm. (5) These findings suggest that 3D CT reconstruction can construct 3D digital models of DDHchildren. Thus, the accurate rotation center of the hip can be identified so as to precisely measure the dislocation length.