The study of percutaneous retrograde screw fixation for acetabular anterior column fractures using a virtual three-dimensional model

Abstract

Objective To discuss the applied anatomical basis of pereutaneous retrograde screw fix-ation for the anterior Column fractures of acetabular. Methods The CT scans images of 164 (80 males and 84 females without any bony problem, with the mean age of 49.1 years) hemipelves were obtained and the virtual three-dimensional reconstruction models were created. Virtual cylindrical implants were placed in-traosseously in the anterior column of acetabular. The maximum diameter, length and the insert direction were determined for lag screws and were calculated. The perpendicular distances from the insert point (A) of virtual cylindrical implants to the rim of superior ramus (B) and pubic symphyses (C) were measured. In the same model, cross-sections of the anterior columns were created and the diameters of them were measured. A disc was placed in the minimum cross-section, and its maximum diameter was measured. Results The mean maximum diameter and length of virtual cylindrical implants were (8.16±1.21) mm and (109.39±8.95) mm. And the angle to the transverse plane, coronal plane and sagittal plane were 39.66°±3.92°、20.81°±4.58°and 42.66°±3.23°respectively. The distant of AB and AC were (18.42±4.82) mm and (17.76±2.63) mm. The dif-ferences of the diameter, length, and distance of AB between the male and female were of statistical signifi-cance. The mean smallest cross-sectional diameter and the mean maximal discs diameter were both larger than the mean maximum diameter of the equivalent virtual cylindrical implants. Conclusion The anterior column of male would accommodate with the screws of 6.5 mm, but not to all of female. The insert points of screws are difference between male and female. The size of the screws used for anterior column should not be based solely on the measurement of cross-sectional diameter. Key words: Acetabulum; Fractures; Bone screws