Investigation of pelvic symmetry using CAD software

Severe pelvic fractures often prove difficult for surgeons as they require patient-specific surgical treatment plans and customized equipment. Developing virtual patient-specific 3D pelvis models would ease the surgical planning process and enable development of custom fixation plates. This paper aims to examine pelvic symmetry to conclude whether the contralateral side may be used as a reference model for the fractured side of the pelvis. Fourteen subjects with intact pelvises were involved in this study. CT scans of the pelvises were converted to 3D models and the right sides of the pelvises were reflected and aligned with the left sides. A deviation analysis was then performed for each set of models and results showed that the average root mean square (RMS) of values was 1.14 +/- 0.26 mm and the average percentage of points below a deviation threshold of +/- 2 mm was 91.9 +/- 5.55%. The deviation color maps (DCMs) showed that the largest deviations were on the non-articular surfaces. The volume and surface area of each model were also examined and showed no significant differences between left and right sides. These results indicate that the pelvis displays bilateral symmetry and this concept can be used to develop fully intact patient-specific 3D pelvis models for fracture reconstruction using the unfractured contralateral side.