Abstract
BackgroundThe infra-acetabular screw which is placed from the pubis to the ischium can be used as a special positional screw of the posterior column of the acetabulum. This study was performed to simulate the surgical procedure and obtain the ideal insertion point, diameter, length and angle of the screw through the method of axial perspective in Chinese patients.MethodsWe randomly collected the pelvic computed tomography (CT) scans of 200 adults. DICOM-formatted CT-scan images were imported into Mimics software to establish the 3D digital model of the right semi-pelvic was established. A virtual cylinder representing the screw was placed from the pubis to the ischium to fix the posterior column. The largest secure diameter and length of the virtual screw were measured and the position of the insertion point and the directions of the screw were also researched.ResultsThe screw insertion safe zone exhibits an irregular shape of “tear drop” in the reconstructed pelvic model. The mean maximum diameter of screws was 5.01 ± 1.28 mm, and the mean maximum length of screws was 93.99 ± 8.92 mm. The screw insertion corridor with the least diameter 3.5 mm was found in 94 of 100 males (94%) and 86 of 100 females (86%). We found gender-dependent differences for the mean maximum diameter and the maximum length of the screw. There was statistically significant difference between genders in the position of insertion point.ConclusionsIn this study, we suggest an individual preoperative 3D reconstruction simulation to develop better screw placement plans, which provides a valuable guideline for seeking the largest secure corridor of infra-acetabular screw. Further biomechanical studies are needed to verify the function of the screw.
Highlights
The infra-acetabular screw which is placed from the pubis to the ischium can be used as a special positional screw of the posterior column of the acetabulum
Digital Imaging and Communication in Medicine (DICOM)-formatted computed tomography (CT)-scan images of each patient were imported into Materialise’s Interactive Medical Image Control System (Mimics) software (20.0; Materialise, Leuven, Belgium)
We reduced the transparency of the semi-pelvic models and turned it to the axial perspective view, which was parallel to the posterior of obturator formamen from top to bottom (Fig 1A)
Summary
The infra-acetabular screw which is placed from the pubis to the ischium can be used as a special positional screw of the posterior column of the acetabulum. Letournel and Judet suggested the ideal screw path is parallel of the quadrilateral wall, in which the screw could fix the quadrilateral fracture and prevent the medial subluxation [8]. The placement of this additional screw can increase the fixation strength of plate for acetabular fractures [4, 5]. On this basis, Culemann et al described the infra-acetabular screw [1]. The knowledge of the correct insertion point and screw direction is essential to avoid penetrating into joint and injury to neurovascular structures [9]
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