Evaluation of preoperative screw planning and X-ray simulation for iliosacral and transsacral screw placement

The percutaneous placement of iliosacral (IS) and transsacral (TS) screws has become a standard practice for the treatment of pelvic fractures. Due to the complex sacral anatomy, accurate screw placement is essential to avoid complications, such as neurovascular injury. The goal of this study was to quantify the deviation between planned and executed screw trajectories and to identify associated factors.

We conducted a retrospective cohort study on treating 51 patients with pelvic fractures from August 2021 to December 2023, using a total of 95 IS and TS screws. Preoperative planning was performed to generate a volume-rendered reconstruction that replicates standard intraoperative fluoroscopic views (lateral, inlet, outlet). These simulated images served as references during surgery. Postoperative Computed Tomography (CT) data were integrated with the preoperative plan to quantify screw deviations through accuracy metrics.

Median deviation from the planned entry point was 8.8 mm (6.2-12.8) for IS and 6.2 mm (4.2-9.0) for TS. Average distances were 5.7 mm (3.5-8.0) for IS and 4.8 mm ± 2.0 for TS. Angle deviation was 8.2° (4.6-12.8) for IS and 3.9° ± 1.8 for TS. One patient experienced loss of sensibility due to an IS screw conflicting with the L5 nerve root, needing revision surgery. A positive association was observed between BMI and the distance between entry points for TS screws. Learning curve analysis showed no significant change in accuracy over time.

Preoperative navigation using volume-rendered virtual imaging could not guarantee a precise positioning of IS and TS screws. Although geometric deviations were observed between planned and placed screws, clinical outcomes were favourable, with a very low complication rate. The technique proved feasible and safe in clinical practice, achieving moderate overall accuracy, and may therefore be particularly valuable for less-experienced surgeons.