Percutaneous, 2D-fluoroscopic navigated iliosacral screw placement in the supine position

Objective. In pelvic surgery, computer-assisted procedures are currently used predominantly for percutaneous iliosacral screw placement. The aim of this study was to evaluate the possibilities and limits of a 2D-fluoroscopic navigated procedure used for this indication. Methods. A consecutive series of patients with non or slightly displaced injuries of the posterior pelvic ring were prospectively investigated. Cannulated cancellous screws of 7.3 mm were percutaneously implanted in the supine position. The navigated procedure was performed using an active optoelectronical system and a 2D C-arm. Target parameters were practicability, precision and intraoperative radiation exposure time compared to patients treated using a non-navigated technique. Results. In a 15 month period, 35 screws were implanted in 20 patients. The average procedure took 36.2 +/- 12.5 min (range 18-62 min), with a fluoroscopic time of 0.9 +/- 0.3 min (range 0.6-1.8 min) per screw. The displacement rate was 8% (n=3/35, CI 1.8-23.0). Compared to retrospectively selected patients treated using a non-navigated technique (n=13), a significant increase in procedure time (P=0.01), a significant decrease of radiation exposure time (P < 0.001) and a decreased displacement rate (P > 0.05) were observed in the navigated group. Conclusion. The 2D-fluoroscopic navigated procedure used in this study can be recommended for percutaneous stabilisation of non or minor displaced injuries of the posterior pelvis. This procedure reduces intraoperative radiation exposure and improves intraoperative orientation but does not crucially enhance the precision of screw placement compared to the non-navigated technique. Finally, it is limited by its poor image resolution and lack of three-dimensionality.