Intraoperative computed tomography with integrated navigation in percutaneous
Kuo-Ti Penga, Yen-Yao Lia, Wei-Hsiu Hsua,*, Meng-Huang Wua, Jen-Tsung Yangb,
Chu-Hsiang Hsub, Tsung-Jen Huanga
aDepartment of Orthopedic Surgery, Chang Gung Memorial Hospital at Chia-Yi, Taiwan
bDepartment of Neurosurgery, Chang-Gung Memorial Hospital, Chia-Yi, Taiwan
Iliosacral screw fixation has generally accepted to treat
unstable pelvic fractures with posterior sacroiliac joint disrup-
tion.1–3Percutaneous iliosacral screwing decreased the invasive
nature and the incidence of wound infections (not uncommon with
open procedures).4,5However, percutaneous iliosacral screwing
was reported 2–16% rate of screw malposition due to the complex
three-dimensional anatomic relationship of the pelvis and
sacrum.6,7Incorrect placement of iliosacral screws can result in
malposition by as little as 48 has resulted in damage to
Various methods, including fluoroscopy,2,10computed tomog-
raphy (CT),11,12fluoroscopic CT, and computer-assisted techni-
ques,3,13–15have been suggested in order to achieve more accurate
screw insertion. Fluoroscopy with lateral sacral images in
combination with the anteroposterior (AP), inlet, and outlet views
of pelvis, were suggested to help surgeons placing the screws more
accurately in the narrow safe zone. However, individual images
corresponding to these four planes were provided sequentially
instead of concomitantly, that might result in inherent errors
during the complicated process of interpolation by surgeons.
Navigation systems based on either CT or fluoroscopy were
developed, but high rate of screw malposition was still reported
due to changes in intersegmental anatomy during transportation
from CT table to final positioning.14,16
The integration of an intraoperative CT (iCT) scanner with a
navigation system was recently developed that offers real time
Injury, Int. J. Care Injured 44 (2013) 203–208
A R T I C L E
I N F O
Accepted 21 September 2012
Intraoperative computed tomography
A B S T R A C T
Background: Iliosacral screw fixation has generally been accepted as a treatment for unstable pelvic
fractures with posterior sacroiliac joint disruption despite a 2–16% rate of screw malposition. The
integration of an intraoperative computed tomography (iCT) with a navigation system was utilized in
percutaneous sacroiliac screwing to provide an alternative.
Methods: From October 2010 to November 2011, thirteen patients presented pelvic fractures with
posterior ring disruption (lateral compression type 2–3 [n = 12] and vertical shear type [n = 1] by Young-
Burgess Classification) and underwent percutaneous iliosacral screwing using an iCT integrated with
navigation system. The perioperative data and radiographic outcomes of the patients were collected and
Results: Navigation times ranged from 10 to 45 min (mean of 21.2 ? 10.6 min). Radiation exposure to the
skin utilizing integrated navigation system ranged from 23.5 to 28.1 mGy (mean of 26.4 ? 1.5 mGy), and the
dose associated with examining the screw position ranged from 22.5 to 26.8 mGy (mean of 25.5 ? 1.1 mGy).
Effective dose of radiation ranged from 9.26 to 17.43 mSv (mean of 13.16 ? 2.52 mSv). The iCT demonstrated
iliosacral screws in adequate position (i.e., no penetration or encroachment of the neuroforamen or cord). No
neurologic or vascular injury occurred in these cases.
Conclusions: An iCT with an integrated navigation system provided accuracy for percutaneous iliosacral
screwing. In addition, the accumulated dose was minimized for surgeons. However, effective dose of
radiation in iCT with an integrated navigation system group was higher than fluoroscopic-assisted
iliosacral screwing in hands of the same group of surgeons. No neurologic complications occurred. The
iCT with an integrated navigation system provided an alternative to percutaneous iliosacral screwing.
? 2012 Elsevier Ltd. All rights reserved.
* Corresponding author. Address: 6 West, Chia-Pu Road, Puzi City, Chia-yi (613),
Taiwan. Tel.: +886 5 3621000x2855; fax: +886 5 3623006.
E-mail addresses: email@example.com (K.-T. Peng),
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firstname.lastname@example.org (C.-H. Hsu), email@example.com (T.-J. Huang).
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its intraoperative CT based registration which avoided errors
associated with changes in intersegmental anatomy during
transportation from CT table in the CT room to final positioning
in the operation room. Those minimization of bias could be
important when the safe zone is narrow in iliosacral screwing. In
the present study, all iliosarcal screws were in adequate position
confirmed by immediate iCT.
Compare to fluoroscopic guidance procedure, even the two C-
arm technique which could decrease the difficulty of procedures in
multiplanar examination,2a navigation system could provide real
time information for iliosacral screw insertion. The preinstall offset
(90 mm) was set in navigation system to identify the adequate
inlet of iliosacral screw (Fig. 3A–D) and replace the lateral view of
fluoroscopic technique. More information from the axial, sagittal
and coronal views could be assessed simultaneously. The
orientation of guide pin in axial, sagittal, coronal, and lateral
views (Fig. 3E–H) replaced the fluoroscopic inlet and outlet views.
The advantages of iCT with the integrated navigation system
minimized the inherent errors of conventional fluoroscopic
technique that commonly occurred during interpolation by the
surgeon. Compare to navigation systems based on either CT or
fluoroscopy, iCT with an integrated navigation system could
perform entire procedure in operating room and avoid the errors
associated with changes in intersegmental anatomy during
transportation from CT room to operation room. As compared to
fluoroscopically controlled iliosacral screwing, the extra-work of
iCT integrated navigation include application of reference tray,
registration and screwing with navigation. Time of these three
steps ranged from 16 to 49 min (mean of 29.46 ? 12.28 min). We
observed a learning curve effect that time of navigation could be
limited within 15 min in the later 5 cases (Fig. 3) which is comparable
to 2C arm fluoroscopic techniques in our previous work (p = 0.810).
For unstable transforaminal sacral fractures, internal fixation
was even technically difficult due to the distorted anatomic
structure and narrower safe zone. In these injuries, iatrogenic
complications were commonly observed. Templeman et al.
showed that malposition of the screw by as little as 48 could
cause damage to neurovascular structures.7Even though iliosacral
screwing for unstable comminuted transforaminal sacral fractures
represents an effective stabilizing procedure, neurovascular
complications ensued under fluoroscopic guidance due to poor
visualization and hence limit its application.18–22Intraoperative
fluoroscopy is often inadequate because of obesity, bowel gas,
intestinal content, dysplastic pelvis, and inadequate machinery.6In
the current series, 8 patients with fracture associated transform-
inal sacral fracture received iliosacral screw fixation using the iCT
integrated navigation system. No screw malposition occurred. This
method could provide accurate position and precise orientation for
unstable comminuted sacral fracture.
No radiation exposure to the surgeons is one of advantage of iCT
with navigation system. For pelvic surgeons, the accumulated
radiation exposure is a major concern while treating large volume
patients. This technique could minimize radiation accumulation
and reduced carcinogenesis. However, from the perspective of
patient, iCT with navigation patients group would have higher
radiation exposure than fluoroscopic-assisted patient group in the
hands of same group of surgeons (Table 2). Of note, postoperative
CT was not included for the fluoroscopic control group. In case that
postoperative CT was performed, the differences on effective dose
of radiation between iCT integrated navigation and fluoroscopi-
cally controlled iliosacral screwing might become insignificant.
Several limitations of this study should be addressed. First, the
small number of patients was enrolled in the current study, because
only pelvic fractures and sacroiliac disruption treated with
percutaneous screw implantation were included. Despite such a
small number of patients in these infrequent injuries, the
reproducibility and precision was well demonstrated. Second, the
equipment and software associated with this technique is of high
cost, indications demands further refinement such as transforaminal
sacral fracture. Third, this short-term study provided only immedi-
ate postoperative radiographic and neurovascular status, long term
follow-up was warranted to demonstrated the clinical outcomes.
In conclusion, an iCT with integrated navigation system for
percutaneous iliosacral screw insertion provided a good alterative
in iliosacral screwing especially for transforaminal sacral fractures.
It reduces the radiation exposure for the operating room personnel.
No neurologic complications occurred.
Conflict of interest statement
The authors declared no conflict of interest. No external funding
was received in the study.
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