CT-GUIDED ILIOSACRAL SCREW FIXATION IN INSTABLE PELVIC RING LESIONS – CLINICAL RESULTS AND TECHNICAL RECOMMENDATIONS

Abstract

Introduction: Percutaneous iliosacral screws are commonly used for the fixation of the posterior pelvis. The procedure is technically demanding because of the limitations of radiological visualisation of the relevant landmarks. There have been several reports of misplaced screws and other complications, occasionally with serious consequences. To achieve a secure surgical procedure we routinely use a CT-guided technique for percutaneous pelvic screw fixation since 2004.

Methods: Between September 2004 and January 2009, 39 patients were treated using CT-guided screw fixation. Under general anaesthesia patients were placed on a vacuum mattress in a stable lateral position within the CT gantry (Siemens SOMATOM definition; i-Fluoro: 20mAs; Hand CARE mode). The scanner bed was on a calibrated track so the same images could be used and repeated throughout the procedure. Gantry and patient were draped under sterile conditions. The laser sights of the CT indicated the cutaneous site which corresponded to the underlying osseous level (first or second sacral pedicle). At this the CT scan trajectory in the CT-fluoro mode indicated the extrapolated position of the guide-wire. A 3.2mm guide-wire was inserted using battery-powered equipment or hammer blows. When the guide-wire was in a correct position a self-drilling cannulated lag screw was placed (6.5mm DePuy). Two screws were inserted in sacral fractures, one screw in sacroiliac ligament ruptures.

Results: 19 of 39 patients were polytraumatized. In 10 cases there were both side injures. Overall 71 screws were placed. Median time for the procedure was 36 minutes in unilateral lesions and 48 min in bilateral lesions. There were no cases of infection, non-union or neurological deficit. Postoperative CT revealed correct screw positions in all cases. Screw removal was done routinely in the patients younger than sixty years to resolve the blocked sacroiliac joint.

Conclusions: CT-guided is a safe and feasible treatment option in patient with instable pelvic ring lesions. A close collaboration between interventional radiologist and surgeon is essential. Compared to other procedures g.e. internal plate fixation or fluoroscopic guided procedures CT-guided screw insertion seems to be more secure and could strongly be advocated.