Evaluation of the ossific development in developmental dysplasia of the hip through three-dimensional coordinate system based on CT

Objective To Evaluate the bone development of the hip in developmental dysplasia of the hip (DDH) by three-dimensional (3D) CT. Methods Preoperative 3D CT was performed for 16 unilateral DDH from Dec, 2010 to Dec, 2014 in Tongji Hospital, with 4 males and 12 females, age rank from 20 months to 9 years. When assessing the CT images, the three dimensional coordinate system were established to analysis the development of hips by a paired self-control study. Additionally, the ossific radius, the dislocation length, and the relationships of those variables with the age, the dislocation length were analyzed. Results The ossific volume of the ilium were (31.14±16.25) cm3 and (32.84±17.36) cm3 for the normal side and dislocation side, respectively (t=2.660, P=0.018). The ossific volume of the ischium were (11.61±5.63) cm3 and (8.62±4.09) cm3 for the normal side and dislocation side, respectively (t=3.041, P=0.008). The ossific volume of the pubis were (4.93±2.73) cm3 and (3.93±1.94) cm3 for the normal side and dislocation side, respectively (t=3.776, P=0.002). The ossific volume of the head and superior part of femur were (23.42±12.48) cm3 and (20.21±8.93) cm3 for the normal side and dislocation side, respectively (t=3.158, P=0.006). It is related to the age but not the dislocation length that the ossific volume of the pubis, the ischium and the superior part of femur. Conclusion Preoperative 3D-CT in cases of DDH revealed the bone development of the hip in DDH. Digital model is thought to help discover the bone characteristics of DDH hips. Older age, less ossific volume of bones. Key words: Three dimensional reconstruction; Three dimensional digital model; Developmental dysplasia of the hip; Ossific development