A positioning method for the transiliac-transsacral screw bone channel based on a manual tracing of a transparent overlay of preoperative computed tomography images in patients with pelvic fracture and a unilateral trans-sacroiliac corridor.

Unstable posterior pelvic ring injuries are carrying a significant mortality risk, and the gold standard treatment for this condition is percutaneous sacroiliac screw fixation. However, traditional methods for transiliac-transsacral screw placement involve numerous difficulties in the positioning of the screw channels. Although computer-assisted navigation can improve accuracy, its complexity and high-cost limit its widespread adoption. This study aimed to develop and implement a positioning method for transiliac-transsacral screw placement via computed tomography (CT) imaging. The proposed technique involves detailed manual tracing of anatomical structures from CT scans onto transparent overlays. This process, performed on sagittal planes, aims to delineate a "safe channel" within the cancellous bone of the sacrum, thereby avoiding sacral nerves, canals, and blood vessels. Proportional measurements derived from these tracings serve as references to guide intraoperative screw placement via standard radiography. A retrospective study of 12 patients with unstable posterior pelvic ring injuries demonstrated the practical applicability of this method. All procedures were performed by a single senior surgeon. Postoperative CT assessments according to the Gertzbein-Robbins scale indicated favorable screw placement accuracy, with no observed complications in this cohort. The study highlights that while computer-assisted navigation remains a superior option when available, this CT-based manual tracing technique offers a viable and safe alternative for settings in which access to advanced navigation systems is limited. Key limitations include the manual nature of the design, the reliance on consistent patient positioning, and the need for further prospective, large-scale, and multioperator studies to validate the reproducibility and long-term efficacy of this approach. A key prerequisite for this technique is achieving adequate reduction and ensuring the presence of a safe bony corridor. A significantly displaced bilateral pelvic fracture, which prevents the formation of a safe corridor, is considered a contraindication to this approach.