Computed tomography fluoroscopy-guided placement of iliosacral screws in patients with unstable posterior pelvic fractures
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- Iguchi, T., Ogawa, K., Doi, T. et al. Skeletal Radiol (2010) 39: 701. doi:10.1007/s00256-009-0826-3
The purpose of this study was to evaluate retrospectively the safety and effectiveness of the computed tomography (CT) fluoroscopy-guided placement of iliosacral screws in patients with unstable posterior pelvic fractures.
Materials and methods
Six patients (four women and two men; mean age 55.8 years; range 35–77 years) with unstable posterior pelvic fractures underwent iliosacral screw placement under CT fluoroscopy guidance between November 2007 and August 2008. Unstable pelvic ring injury (AO types B and C) was the indication for this procedure.
In all the six patients except one, CT fluoroscopy-guided placement had been technically successful. In one patient, a second screw had been inserted, with a tilt to the caudal site, and slightly advanced into the extrasacral body; afterward, it could be exchanged safely for a shorter screw. Five patients and one patient underwent placement of two screws and one screw, respectively. The mean duration of the procedure was 15.0 min (range 9–30 min) per screw; the duration was 12.3 min and 18.2 min for the first and second screws, respectively. No complications requiring treatment occurred during or after the procedure. The mean clinical and radiologic follow-up period was 14 months (range 6–21 months). All pelvic injuries had healed satisfactorily, without complication, and all patients are now doing well clinically and can walk.
CT fluoroscopy-guided placement of iliosacral screws is a safe and effective treatment in patients with unstable posterior pelvic fractures.
KeywordsPelvisFractureScrew fixationComputed tomography fluoroscopy
Percutaneous placement of iliosacral screws, one of the established treatments for unstable posterior pelvic fractures, is performed for fixing the posterior pelvis [1–6]. Although, traditionally, the placement of iliosacral screws was performed under fluoroscopy guidance in an operating room, it was sometimes difficult to insert the screws safely and accurately without advancing into the sacral foramina or extrasacral body. This was due to the insufficient visualization and assessment of the posterior pelvic anatomy under fluoroscopic guidance [1, 2]. The incidence of screw malpositioning under fluoroscopic guidance is reported to be 2.8–13.2% [1, 2]. Anatomically, the sacral nerves and venous plexus are in the sacral foramina and anterior to the sacral body, respectively. Incorrect advancement into the sacral foramina or extravertebrally results in injury to these structures and causes major complications, including nerve damage and massive hemorrhage. It is reasonable and desirable to perform percutaneous screw placement under computed tomography (CT) guidance, as this would enable an accurate assessment to be made of the posterior pelvic anatomy, positions of the guidewire and screw, and complications of the procedure on CT images during and immediately after the procedure. In fact, some orthopedists and interventional radiologists perform this procedure under CT guidance, and they have reported excellent results and advantages, including feasibility, safety, accuracy, and cost effectiveness, with CT guidance [3–6]. However, to the best of our knowledge, those authors placed the screws under conventional CT guidance and not under CT fluoroscopy guidance.
With the recent advances in modalities and equipment, interventional radiology techniques have also improved, enabling their application in many regions, including the thoracic, abdominal, and musculoskeletal areas. The use of CT fluoroscopy is one of the representative improvements. Moreover, compared with procedures performed under conventional CT guidance, those performed under CT fluoroscopy guidance have been reported to exhibit better technical accuracy, require less time, and produce lower radiation [7, 8].
The purpose of this study was to evaluate retrospectively the safety and effectiveness of the CT fluoroscopy-guided placement of iliosacral screws in patients with unstable posterior pelvic fractures.
Materials and methods
The patients or their family members had given informed consent to the placement of the iliosacral screws. Our institutional review board does not advocate the need for approval of retrospective reports.
Summary of information on patients and procedures (F female, M male)
Classification of pelvic fracture
Laterality of placement
Number of screws placed
Procedure time (min)
Follow-up period (months)
Placement of iliosacral screws
The procedure was performed percutaneously under CT fluoroscopy guidance (Aquilion; Toshiba, Tokyo, Japan) in an interventional radiology room. CT fluoroscopy images were acquired at a scanning speed of 0.50 s per rotation (360°) with a voltage of 120 kV, current of 30 mA, and collimation of 3 mm. To reduce radiation exposure, CT fluoroscopy was performed intermittently; it was used only to confirm and adjust the positions of the guidewire and screw and was not used during their advancement. Further, the guidewire and screw were held with a pair of 19 cm-long plastic forceps during CT fluoroscopy to maintain their positions and avoid direct radiation exposure to the operator’s hands.
The patients were placed in a semi-lateral position under general anesthesia, and CT images were obtained prior to screw placement. The selected path for the iliosacral screw placement bypassed the sacral foramina and large vessels. A skin incision was made; subsequently, a guidewire (Best Medical Co., Saitama, Japan) was hammered and inserted into the sacral vertebral body. After the appropriate position of the guidewire had been confirmed on CT fluoroscopy images, a cannulated cancellous screw (diameter 7.5 mm; Best Medical Co.) and a washer (Best Medical Co.) were passed through the guidewire by forward pressure and rotation. If possible, another screw was placed by the above-described method. Small wounds were closed after the withdrawal of the guidewire. Finally, conventional CT images and three-dimensional images, which were reconstructed from CT images, were obtained to confirm the position of the implanted screws and to check for complications.
The mean clinical and radiologic follow-up period was 14 months (range 6–21 months). All pelvic injuries had healed satisfactorily, without complications, and all patients are now doing well clinically and can walk.
In 1987 Ebraheim et al. first reported CT-guided placement of iliosacral screws as a safe and accurate technique . Since then, some studies on CT-guided screw placement have reported some advantages of and excellent results with this procedure in comparison with fluoroscopy guidance in an operating room [3–6]. This procedure is feasible, appropriate, and safe. The accuracy of screw positioning was 93–100% [3–5]. There were no reports of complications that would require treatment [3–6]. Only a few complications were reported: one case of screw breakage at the final follow-up out of 113 screws placed in 66 patients , and one case of screw breakage and two case of axial dislocations out of 27 screws placed in 13 patients . Additionally, the CT-guided placement of iliosacral screws is considered to be more cost effective than fluoroscopy-guided placement in an operating room [3, 4]. In all our six patients this procedure was very effective, as well as that in other previous reports of conventional CT-guided placement of iliosacral screws [3–6]. All pelvic injuries had healed satisfactorily without complications and all patients can now walk.
With conventional CT, operators need to ask a technician to scan, and then have to wait for reconstruction and display of the images after scanning . Conversely, with CT fluoroscopy, operators are able to obtain the images anytime by themselves . Further, CT fluoroscopy is able to provide rapid reconstruction and display of CT images on a monitor as efficiently as sonography and fluoroscopy. Therefore, since the development of CT fluoroscopy in 1993 , many of its potential advantages, such as decreased patient radiation dose, shorter procedure time, and increased procedure efficacy [7, 8], have benefited many interventional radiology procedures (e.g., biopsy, drainage, and radiofrequency ablation) and patients. Carlson et al. reported that the median patient radiation dose per procedure and the procedure time for CT fluoroscopy (n = 203) were, respectively, 94% less and 32% less than the corresponding values for conventional CT (n = 99) (P < 0.05) .
In the largest report of conventional CT-guided placement of iliosacral screws, Ziran et al. reported that the mean duration of the procedure per screw was 26 min (range 18–45 min) and expected the use of CT fluoroscopy to shorten the procedure time further . In accordance with their expectation, the mean procedure time per screw was shorter (15.0 min) in our series. Because the placement of the second screw was more time consuming than that of the first screw, this indicated that the placement of the second screw was more difficult than that of the first screw, possibly because the first screw had already been placed in the best position. In future, our procedure time may be much shorter because of our learning curve.
In both conventional CT-guided and CT fluoroscopy-guided placement of iliosacral screws, it is more difficult for one to confirm the trajectories of the guidewire and screw than with fluoroscopy-guided placement when they are inserted with a tilt to the cranial or caudal site. The CT gantry-tilt technique is a modified approach to overcome this disadvantage . However, even if this technique is used, it is sometimes insufficient to maintain visualization of the entire guidewire and screw during their advancement. In such cases it is necessary to confirm their tip positions more carefully. Actually, in our patients, one screw was inserted with a tilt to the caudal site and was slightly advanced into the extrasacral body even if the CT gantry was tilted; fortunately, no complications requiring treatment occurred, and, afterward, it could be exchanged safely for a shorter screw.
There are several limitations to this study. It was retrospectively designed and included a small number of patients in a single institution. The follow-up period was not sufficiently long. Further, our study was not designed to compare the safety and effectiveness of the placement of iliosacral screws under CT fluoroscopy guidance and conventional CT guidance. In future, it would be interesting to compare the procedure time and radiation exposure between CT fluoroscopic guidance and conventional CT guidance.
In conclusion, CT fluoroscopy-guided placement of iliosacral screws is a safe and effective treatment in patients with unstable posterior pelvic fractures. Additionally, compared with conventional CT-guided placement, it may have some potential benefits, including decreased patient radiation dose, shorter procedure time, and increased procedure efficacy.