A digital anatomy study of the secure corridor for infra-acetabular screw placement / 中华创伤骨科杂志

ABSTRACT

Objective:To compare the parameters for infra-acetabular screw placement between men and women using a digital Chinese anatomical model of the pelvis and acetabulum.Methods:The normal pelvic CT data were collected from the 163 adult patients who had been admitted to the Traditional Chinese Medicine Hospital of Xinjiang Uygur Autonomous Region from January 2018 to December 2021. There were 61 males and 102 females with an age of 53.0 (45.0, 60.0) years. Mimics 21.0 software was used to reconstruct the three dimensional pelvis which was then imported into Autodesk maya 2022 software before the model was flattened. Polygonal modeling tools were used to create a cylinder to simulate an infra-acetabular screw for length and angle measurements of the screw. The diameters of the infra-acetabular screws were measured by axial fluoroscopy in Mimics 21.0 software. The maximum diameters and maximum lengths of the infra-acetabular bone channel were compared between males and females, and the angles between the axis of the infra-acetabular screw and the anterior pelvic plane and the median sagittal plane were also compared between genders.Results:The maximum diameters of the left and right infra-acetabular corridors were 5.24 (4.26, 6.38) mm and 5.04 (4.50, 6.57) mm in males, and 3.99 (3.81, 4.51) mm and 3.89 (3.65, 4.90) mm in females; the maximum lengths of the left and right infra-acetabular corridors were (98.43±4.42) mm and (98.01±5.08) mm in males and 87.73 (84.22, 90.98) mm and 87.51 (84.59, 90.15) mm in females. The left and right angles between the infra-acetabular screw axis and the median sagittal plane were -0.98°±4.79° and -1.08°±4.91° in men, and 6.20° (3.34°, 11.16°) and 6.44° (3.77°, 11.85°) in women. The differences in the above data between men and women were statistically significant ( P<0.05). There was no statistically significant difference between men and women in the angle between the infra-acetabular screw axis and the anterior pelvic plane ( P>0.05). Conclusions:The length and diameter of the infra-acetabular corridor in males are greater than those in females, the angle between the infra-acetabular corridor and the sagittal plane in males is smaller than that in females, and the infra-acetabular corridor in males is more parallel to the sagittal plane. Therefore, the fluoroscopy angle should be adjusted for males to reduce the difficulty in screw placement when an infra-acetabular screw is placed during surgery.