Morphometry of iliac anchorage for transiliac screws: a cadaver and CT study of the Eastern population

To describe the morphometry of iliac columns for transiliac screw and to testify the conformity among the anatomic measurement, two-dimensional (2D) and three-dimensional (3D) computed tomography.

We evaluated the length, inner width, and angle of three screw trajectories starting at the iliac tubercle, posterior superior iliac spine, and posterior inferior iliac spine toward the anterior inferior iliac spine. Measurements were made on specimen, two- and 3D computed tomography using 18 embalmed cadaveric pelves.

There was no significant difference among three measure methods. The path between the posterior superior iliac spine and anterior inferior iliac spine had the largest iliac column length, with 135 mm in male and 110 mm in female. The canal allowed placement of 8-mm screw in male and 6.5 mm in female with the angle of 25 degrees laterally directed from the midsagittal plane. The line between the posterior inferior iliac spine and anterior inferior iliac spine was below or just located at the top of greater sciatic notch in the majority measurements. The safe section for transiliac screw approximately located above the greater sciatic notch and could be divided into anterior and posterior parts.

The measurements among anatomic measurement, 2D and 3D computed tomography are consistent. The screw path from the posterior superior iliac spine toward anterior inferior iliac spine provided the longest anchor site. At the same time, the line between the posterior inferior iliac spine and anterior inferior iliac spine is not available for transiliac screw insertion of eastern population. The posterior of the safe section also can be regarded as another ilium anchorage area for transiliac screws.