Effect of Iliosacral Screw Implantation Through a New Channel in Three-Dimensional Printing Pelvic Model.

Background: The exit point of classic iliosacral screw (ISS) is deep and viewing device cannot be used, implantation of ISS may lead to malposition and nerve injury. Objective: The aim of this study is to explore the effect of ISS implanted through a new channel (NSIS) with the aid of a viewing device. Methods: With the aid of a viewing device, NISSs were implanted into 50 3D printed pelvis models (1:1), in which the entry point was located at a vertical distance of 6 mm from the middle of the superior posterior quarter of the acetabular rim, and the exit point was the intersection of the vertical extension line of S1 superior articular process and the horizontal median line of S1 transverse process. Screws with diameter of 6.5 mm and 7.3 mm and length of 90 mm were implanted into the left and right sides of the pelvic models, respectively. The implantation was observed. CT scan was performed when penetrating of channel was suspected. Results: None of the implanted screws perforated the tunnel, but 6.0% (3 models) of the screws were too long and a little bit penetrated (< 4 mm) behind the back of the tunnel, which was found in small models. Conclusion: The NISS implantation is simple, safe and accurate, but individualized screw implantation with appropriate diameter and length should be more accurate. Trial registration number: WXSJY-LY-2020-00216, date of registration: June 5, 2020, retrospectively registered. [ABSTRACT FROM AUTHOR]