Digital anatomical study of screw placement for quadrilateral plate through the middle window of ilioinguinal approach

Abstract

Background Screw placement directly for quadrilateral plate fractures of the acetabulum is very difficult. This study was performed to simulate the surgical procedure and try to obtain effective and safe screw angles through the middle window of ilioinguinal approach in Chinese patients. Methods We randomly collected the pelvic computed tomography (CT) scans of 50 adults. DICOM-formatted CT-scan images were imported into Mimics software. The three-dimensional reconstruction (3D) digital model of the semi-pelvic was established. In the coronal and sagittal planes, a 3.5 mm cylinder was used to simulate the pathway of the screw from the designated insertion point. The angles of insertion and intersex differences were explored by statistical analyses. Results The screws could be inserted via four angles: medial inclination, lateral inclination, anterior inclination and posterior inclination. The mean minimum medial inclination angle (MIMIA) of insertion point A was 4.96°±1.11° in males and 8.66°±3.40° in females, and the intersex difference was significant. The mean minimum medial inclination angle (MIMIA) of insertion point C was -5.31°±3.69° in males and 1.75°±8.95° in females, and the intersex difference was significant. There were no differences in all the angles between males and females in insertion point B. Conclusions Preoperative measurement and calculation by digital tools before the screw placement for quadrilateral plate fractures of the acetabulum are feasible. Double cortical screws could be placed safely through the middle window of ilioinguinal approach to increase the stability of acetabulum.