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Radiation Exposure in Posterior Lumbar Fusion: A Comparison of CT Image-Guided Navigation, Robotic Assistance, and Intraoperative Fluoroscopy

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Study Design Retrospective clinical review. Objective To assess the use of intraoperative computed tomography (CT) image-guided navigation (IGN) and robotic assistance in posterior lumbar surgery and their relationship with patient radiation exposure and perioperative outcomes. Methods Patients ≥18 years old undergoing 1- to 2-level transforaminal lateral interbody fusion in 12-month period were included. Chart review was performed for pre- and intraoperative data on radiation dose and perioperative outcomes. All radiation doses are quantified in milliGrays (mGy). Univariate analysis and multivariate logistic regression analysis were utilized for categorical variables. One-way analysis of variance with post hoc Tukey test was used for continuous variables. Results A total of 165 patients were assessed: 12 IGN, 62 robotic, 56 open, 35 fluoroscopically guided minimally invasive surgery (MIS). There was a lower proportion of women in open and MIS groups ( P = .010). There were more younger patients in the MIS group ( P < .001). MIS group had the lowest mean posterior levels fused ( P = .015). Total-procedure radiation, total-procedure radiation/level fused, and intraoperative radiation was the lowest in the open group and highest in the MIS group compared with IGN and robotic groups (all P < .001). Higher proportion of robotic and lower proportion of MIS patients had preoperative CT ( P < .001). Estimated blood loss ( P = .002) and hospital length of stay ( P = .039) were lowest in the MIS group. Highest operative time was observed for IGN patients ( P < .001). No differences were observed in body mass index, Charlson Comorbidity Index, and postoperative complications ( P = .313, .051, and .644, respectively). Conclusion IGN and robotic assistance in posterior lumbar fusion were associated with higher intraoperative and total-procedure radiation exposure than open cases without IGN/robotics, but significantly less than MIS without IGN/robotics, without differences in perioperative outcomes. Fluoro-MIS procedures reported highest radiation exposure to patient, and of equal concern is that the proportion of total radiation dose also applied to the surgeon and operating room staff in fluoro-MIS group is higher than in IGN/robotics and open groups.
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Original Article
Radiation Exposure in Posterior Lumbar
Fusion: A Comparison of CT Image-Guided
Navigation, Robotic Assistance, and
Intraoperative Fluoroscopy
Erik Wang, BA
1
, Jordan Manning, BA
1
, Christopher G. Varlotta, BS
1
,
Dainn Woo, BS
1
, Ethan Ayres, MPH
1
, Edem Abotsi, BA
1
,
Dennis Vasquez-Montes, MS
1
, Themistocles S. Protopsaltis, MD
1
,
Jeffrey A. Goldstein, MD
1
, Anthony K. Frempong-Boadu, MD
1
,
Peter G. Passias, MD
1
, and Aaron J. Buckland, MBBS, FRACS
1
Abstract
Study Design: Retrospective clinical review.
Objective: To assess the use of intraoperative computed tomography (CT) image-guided navigation (IGN) and robotic assis-
tance in posterior lumbar surgery and their relationship with patient radiation exposure and perioperative outcomes.
Methods: Patients 18 years old undergoing 1- to 2-level transforaminal lateral interbody fusion in 12-month period were
included. Chart review was performed for pre- and intraoperative data on radiation dose and perioperative outcomes. All
radiation doses are quantified in milliGrays (mGy). Univariate analysis and multivariate logistic regression analysis were utilized for
categorical variables. One-way analysis of variance with post hoc Tukey test was used for continuous variables.
Results: A total of 165 patients were assessed: 12 IGN, 62 robotic, 56 open, 35 fluoroscopically guided minimally invasive surgery
(MIS). There was a lower proportion of women in open and MIS groups (P¼.010). There were more younger patients in the MIS
group (P< .001). MIS group had the lowest mean posterior levels fused (P¼.015). Total-procedure radiation, total-procedure
radiation/level fused, and intraoperative radiation was the lowest in the open group and highest in the MIS group compared with
IGN and robotic groups (all P< .001). Higher proportion of robotic and lower proportion of MIS patients had preoperative CT (P
< .001). Estimated blood loss (P¼.002) and hospital length of stay (P¼.039) were lowest in the MIS group. Highest operative
time was observed for IGN patients (P< .001). No differences were observed in body mass index, Charlson Comorbidity Index,
and postoperative complications (P¼.313, .051, and .644, respectively).
Conclusion: IGN and robotic assistance in posterior lumbar fusion were associated with higher intraoperative and total-
procedure radiation exposure than open cases without IGN/robotics, but significantly less than MIS without IGN/robotics,
without differences in perioperative outcomes. Fluoro-MIS procedures reported highest radiation exposure to patient, and of
equal concern is that the proportion of total radiation dose also applied to the surgeon and operating room staff in fluoro-MIS
group is higher than in IGN/robotics and open groups.
Keywords
radiation, intraoperative CT, image-guided navigation, robotic surgery, minimally invasive surgery
Introduction
As rates of lumbar spinal instrumentation and minimally inva-
sive surgery (MIS) continue to increase, methods to improve
accuracy and reduce radiation burden have concurrently
adapted. Pedicle screws are used to improve fusion rates but
1
NYU Langone Orthopedic Hospital, New York, NY, USA
Corresponding Author:
Aaron J. Buckland, Spine Research Center, Department of Orthopaedic
Surgery, NYU Langone Health, 306 East 15th Street, Ground Floor, New
York, NY 10003, USA.
Email: aaronbuckland@me.com
Global Spine Journal
1-8
ªThe Author(s) 2020
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their placement can be challenging, and misplacement can lead
to neurologic damage, vascular and visceral structure damage,
persistent pain, revision surgeries, and higher overall costs.
1,2
Utilization of 2-dimensional fluoroscopic navigation, which
has been the mainstay of multiple medical disciplines since
gaining popularity in the 1980s, has been shown to reduce the
number of misplaced screws.
3-6
Despite this, however, pedicle
screw misplacement has been estimated to occur between 5%
and 30%of spine procedures involving freehand and fluoros-
copically guided placement.
7-13
New technologies have been
increasingly used to improve the accuracy of pedicle screw
positioning and patient safety, including robotic navigational
guidance and intraoperative computed tomography (CT)
image-guided navigation (IGN).
14-20
A major topic of discussion regarding novel methods of
navigational assistance in spine surgery is radiation exposure,
chiefly the balance of who is exposed and to what dosage.
Radiation exposure in spinal procedures, especially in MIS,
is of concern to everyone involved in the surgery, including
the patient, surgical team, and operating room staff. Dosimetry
readings during fluoroscopically guided spinal surgery have
been shown to be 10 to 12 times greater than those in nonspine
orthopedic procedures, based on measured fluoroscopy
times.
21
Other than the patient, surgeons generally receive the
highest dose due to their proximity to radiation scatter
6,22-25
(Figure 1). Thus, it is crucial to consider the radiation dosages
given not only to the patient perioperatively but also to the
operating room staff.
Several studies have raised concerns over radiation expo-
sure with both robotic assistance and IGN, particularly in
weighing the reduction of intraoperative radiation exposure
to operative staff against potentially increased exposure to the
patient.
26-28
Radiation exposure for spine surgeons using con-
ventional fluoroscopy may approach or exceed the annual
cumulative exposure acceptable for established lifetime dose
equivalent limits.
24,29
However, a single acquisition required
for IGN has also been shown to expose the patient to the
equivalent of 4.35 years’ background radiation.
1
The purpose
of this study was to assess the use of IGN and robotic assis-
tance in 1- or 2-level transforaminal lateral interbody fusion
(TLIF) surgeries, along with their relationship to patient
radiation exposure and perioperative outcomes. This study
is, to our knowledge, the first to compare this across IGN,
robotic assistance, fluoroscopically guided MIS (fluoro-MIS),
andopenTLIF.
Materials and Methods
Data Source and Inclusion Criteria
A retrospective review from January 2018 to December
2018 was conducted for adult patients (18 years) under-
going 1- or 2-level TLIF at a single academic institution. 19
spine surgeons were involved in the study, all of whom
were fellowship trained in either orthopedic surgery or neu-
rosurgery. All surgeons were required to perform radiation
safety courses as part of hospital accreditation. Patients
were grouped by type of guidance used for pedicle screw
insertion: intraoperative CT IGN, robotic assistance, fluoro-
MIS, and open surgery. IGN was utilized by 2 different
surgeons, who each primarily performed IGN cases. Robotic
assistance was used by 7 different surgeons, one of whom
performed more than half of all robotic cases. Sixteen dif-
ferent surgeons performed open cases and 9 different sur-
geons performed fluoro-MIS cases (Table 1). In all cases, a
radiation technician was present to operate the fluoroscopy
as per hospital radiology guidelines.
Robotic Guidance System
The robotic guidance system used at our institution is the
ExcelsiusGPS system (Globus Medical Inc, Audubon, PA,
USA). The system was used for open and mini-open cases, as
well MIS cases in lieu of conventional fluoroscopic guidance
during pedicle screw insertion. Patients who underwent preo-
perative CT scanning outside the operating room had their
images uploaded to the proprietary software prior to surgery.
After fiducial marker placement, all patients underwent intrao-
perative fluoroscopic registration, and these images were
merged with preoperative CT data. This method allowed the
robotic arm to be stereotactically positioned in order to guide
Figure 1. Scattered radiation during intraoperative fluoroscopy of
the lumbar spine. Primary beam: x-ray beam prior to any interaction
with the patient, grid, table or image intensifier. Exit beam: beam that
interacts with the detector. Leakage radiation (green): leakage from
the x-ray tube housing that does not contribute significantly to staff
dose. Scattered radiation (red): radiation resulting from Compton
scattering in the patient that contributes most to staff radiation dose.
Backscatter of radiation is more pronounced toward the source side.
2Global Spine Journal
incision marking, drilling, and pedicle screw insertion. Final
fluoroscopic imaging was performed to confirm implant posi-
tioning (Figure 2).
Intraoperative CT Image-Guided Navigation
The IGN system used at our institution is the Airo mobile
intraoperative CT scanner (BrainLab, Munich, Germany). The
system was used for open instrumented cases. With this system,
a radiology technician executes scans intraoperatively with a
mobile CT scanner after placement of a fiducial marker on a
known anatomical landmark. Images were transferred automat-
ically to the navigation workstation, which enabled the surgeon
to guide screw placement via simultaneous axial, sagittal, and
coronal views displayed on the navigation system. Postinstru-
mentation imaging was performed via 2D fluoroscopy or
intraoperative CT depending on surgeon preference (Figure 3).
Data Collection and Outcome Measures
Chart review was performed for demographic data (age, gen-
der, body mass index [BMI], and Charlson comorbidity index
[CCI]), preoperative and intraoperative radiation dose and peri-
operative outcomes. Preoperative CT scan utilization and
radiation dose, intraoperative radiation dose and time (via use
of fluoroscopy and/or CT) and total-procedure radiation dose
(sum of preoperative CT and intraoperative radiation doses)
were assessed. Total-procedure radiation dose per level
involved during surgery was also calculated by dividing
total-procedure radiation dose by the number of levels involved
in surgery. All radiation doses were determined from the
DICOM Radiation Dose Structured Reports (RDSR) and quan-
tified in milliGrays (mGy). Surgical data assessed included
levels fused, estimated blood loss (EBL), length of stay (LOS),
operative time, and general perioperative complications
(including cardiac, urinary and neurologic complications,
along with ileus and surgical site infection).
Statistical Analysis
Statistical analysis was performed using the Statistical Pack-
age for Social Sciences, version 23 (IBM Corp, Armonk, NY).
Univariate analysis and multivariate logistic regression anal-
ysis for categorical variables and 1-way analysis of variance
for continuous variables were utilized. Significance was set
at P<.05.
Results
Patient Sample and Demographics
A total of 165 patients underwent 1- or 2-level TLIF during the
study period (51.83%female, 48.17%male). Mean age was
59.13 +13.18 years, BMI was 29.43 +6.72 kg/m
2
, and CCI
1.20 +1.56. Twelve cases utilized intraoperative CT IGN for
pedicle screw placement and 62 used robotic assistance. In all,
56 cases were open and 35 were fluoroscopically guided MIS.
The open (38.18%female) and fluoro-MIS (45.71%female)
Table 1. Total Number of Cases Performed by Surgeon.
Surgeon Total Number of Cases Performed
12
27
34
42
57
61
735
81
914
10 1
11 23
12 8
13 5
14 11
15 11
16 1
17 11
18 12
19 9
Figure 2. Operating room setup of intraoperative robotic assistance
system for transforaminal lateral interbody fusions (TLIFs) at our
institution.
Wang et al 3
patient groups had a lower proportion of females compared
with the IGN (66.67%female) and robotic (64.52%female)
patient groups (P¼.021, Table 2). Patients were also younger
in the MIS group (50.63 years) compared with the other groups
(63.42 years in IGN, 61.74 years in robotic, 60.63 years in
open; P< .001). There were no differences in BMI (P¼
.313) among any of the groups, though there was a trend toward
higher CCI in IGN (1.83) and open (1.54) patients compared
with robotic (0.98) and MIS patients (0.83, P¼.051).
Perioperative Outcomes
The fluoro-MIS group had the lowest mean posterior levels
fused (1.06 levels in MIS vs 1.42 in IGN, 1.27 in robotic, and
1.32 in open; P¼.015, Table 3). EBL was significantly lower
in the MIS group compared with all others (162.14 vs 441.67
mL in IGN, 380.24 mL in robotic, and 355.36 mL in open; P¼
.002) and this was confirmed with post hoc Tukey test. LOS
was also lowest in the MIS group (2.83 vs 4.75 days in IGN,
3.89 days in robotic, and 3.89 days in open; P¼.039), but post
hoc Tukey test showed that this was not a significant difference
in paired comparisons. Operative time was highest for IGN
patients (303.5 vs 264.85 minutes robotic, 229.91 minutes
open, and 213.43 minutes MIS; P< .001). Post hoc Tukey
test showed that there was a significant difference in operative
time comparing IGN patients with MIS and open patients but
not with robotics patients. There were no significant differ-
ences in postoperative complications among any of the groups
(P¼.644).
Radiation Exposure
Total-procedure radiation was highest in the fluoro-MIS
group, followed by the robotics, IGN and then open groups
(P< .001, Table 4). Total-procedure radiation per level fused
Table 2. Differences in Demographics Among Different TLIF Methods.
Total (n ¼165) IGN (n ¼12) Robotic (n ¼62) Open (n ¼56) MIS (n ¼35) P
Gender (female), % 51.83 66.67 64.52 38.18 45.71 .021
Age, y 59.13 +13.18 63.42 +8.56 61.74 +11.78 60.63 +13.9 50.63 +12.48 <.001
BMI, kg/m
2
29.43 +6.72 27.1 +3.36 28.79 +6.97 29.82 +6.67 30.78 +7.1 .313
CCI 1.20 +1.56 1.83 +1.34 0.98 +1.19 1.54 +1.94 0.83 +1.4 .051
Abbreviations: TLIF, transforaminal lateral interbody fusion; IGN, intraoperative computed tomography image-guided navigation; robotic, robotic assistance; MIS,
minimally invasive surgery with fluoroscopy; BMI, body mass index; CCI, Charlson Comorbidity Index.
Figure 3. Operating room setup of intraoperative computed tomo-
graphy (CT) image-guidance navigation system for transforaminal lat-
eral interbody fusions (TLIFs) at our institution.
Table 3. Differences in Perioperative Outcomes Among Different TLIF Methods.
Total (n ¼165) IGN (n ¼12) Robotic (n ¼62) Open (n ¼56) MIS (n ¼35) P
Posterior levels fused 1.25 +0.44 1.42 +0.51 1.27 +0.45 1.32 +0.47 1.06 +0.24 .015
EBL, mL 330 +308.14 441.67 +180.7 380.24 +349.04 355.36 +301.01 162.14 +207.93 .002
LOS, d 3.73 +2.31 4.75 +1.14 3.89 +2.64 3.89 +1.74 2.83 +2.55 .039
Operating time, min 244.9 +70.38 303.5 +67.53 264.85 +73.16 229.91 +60.03 213.43 +60.46 <.001
Postoperative complication, % 15.15 8.33 19.35 14.29 11.43 .644
Abbreviations: TLIF, transforaminal lateral interbody fusion; IGN, intraoperative computed tomography image-guided navigation; robotic, robotic assistance; MIS,
minimally invasive surgery with fluoroscopy; EBL, estimated blood loss; LOS, length of stay.
4Global Spine Journal
was also highest in the MIS group, following the same hier-
archy (P< .001). This was also the case for intraoperative
radiation (P< .001). A higher proportion of robotic and lower
proportion of MIS patients underwent preoperative CT (25%in
IGN, 82.26%in robotic, 37.5%in open, 8.57%in MIS; P<
.001). There was no difference in preoperative radiation dose
among patients who underwent preoperative CT (P¼.931).
Fluoroscopy Time
Mean intraoperative fluoroscopy time by surgeon by type of
guidance used for pedicle screw insertion was assessed to see if
there were differences in radiation usage time among different
surgeons. Surgeons were grouped by those who performed
majority MIS cases, majority open cases and majority roboti-
cally assisted cases. Surgeons 5 and 12, who performed major-
ity IGN cases, were excluded due to minimal fluoroscopy
usage during IGN cases. Surgeons 1, 4, 6, 8, 10, and 16 were
excluded from comparison due to having 2 or fewer total
patients. There was no significant difference in fluoroscopy
time among the surgeons who performed majority open cases
and majority robotic cases (P¼.782 and .785, respectively,
Table 5). There was a greater variation in fluoroscopy time for
surgeons performing the majority MIS cases, with Surgeons
11 and 15 in particular having higher mean fluoroscopy times
(P¼.074, Table 5).
Discussion
Advancements in imaging technology have diversified the
options of image guidance techniques in the surgical proce-
dures of various disciplines. Robotic navigational guidance and
intraoperative CT IGN have been increasingly used in spine
surgeries in an attempt to improve patient safety and the pre-
cision of pedicle screw placement. In addition to assessing
cost-effectiveness and accuracy of screw positioning in these
operations, an important topic of discussion pertaining to novel
methods of navigational assistance is radiation exposure. While
several studies have explored the risks of radiation exposure for
the patient, surgeon, and operating room staff when using
fluoroscopic guidance, there is a lack information comparing
it with robotic assistance and IGN.
6,22-25
Because of this, our
study aimed to assess the relationship between types of gui-
dance used for pedicle screw placement and patient radiation
exposure, along with perioperative outcomes.
In this study, we compared 4 types of guidance for pedicle
screw placement in TLIF surgeries: IGN, robotic assistance,
open surgery, and fluoroscopic-MIS. Overall, the fluoro-MIS
cohort had younger patients and less levels fused and also
trended toward a lower mean CCI. Unsurprisingly, EBL was
also lowest in the MIS cohort in comparison with the IGN,
robotic and open groups, which were comparable. Though
analysis of variance showed a significant difference in LOS
between groups (P¼.039), with the MIS group having the
lowest mean, post hoc analysis demonstrated that there were
no significant differences between groups. We also found a
higher proportion of females in the open and fluoro-MIS
cohorts compared with the IGN and robotic groups (P¼
.021), though it is questionable how clinically relevant this is,
especially given some of the smaller cohort sizes. There were
no significant differences in postoperative complications
among any of the groups.
Regarding operative time, surgeries using IGN had the long-
est procedures on average (303.5 minutes), followed by roboti-
cally assisted surgeries (264.85 minutes), both of which were
longer than open (229.91 minutes) and MIS (213.43 minutes)
procedures with conventional fluoroscopy use (P< .001).
While IGN procedures were significantly longer than open and
MIS procedures, post hoc analysis showed no difference
Table 4. Differences in Radiation Exposure Among Different TLIF Methods.
Total (n ¼165) IGN (n ¼12) Robotic (n ¼62) Open (n ¼56) MIS (n ¼35) P
Total-procedure radiation, mGy 51.19 +42.02 50.21 +22.84 59.84 +32.48 22.56 +22.62 82.02 +56.24 <.001
Total-procedure radiation per level, mGy 45.52 +40.97 41.88 +27.70 51.18 +32.05 18.56 +19.53 79.41 +54.25 <.001
Intraoperative radiation, mGy 42.16 +41.81 44.69 +13.08 44.85 +34.61 14.81 +15.54 80.28 +55.6 <.001
Preoperative CT, % 47.27 25.00 82.26 37.50 8.57 <.001
Preoperative CT radiation, mGy 19.88 +9.48 22.09 +19.67 19.36 +7.32 20.67 +12.28 20.28 +12.16 .931
Abbreviations: TLIF, transforaminal lateral interbody fusion; IGN, intraoperative computed tomography image-guided navigation; robotic, robotic assistance; MIS,
minimally invasive surgery with fluoroscopy.
Table 5. Mean Intraoperative Fluoroscopy Time by Surgeon by Type
of Guidance Used for Pedicle Screw Insertion.
a
Surgeon Fluoroscopy Time, s P
Majority MIS cases 2 49.60 .074
3 37.45
11 106.42
15 101.58
19 67.61
Majority open cases 9 24.24 .782
13 12.27
17 21.75
Majority robotic cases 7 48.12 .785
14 44.40
18 43.47
Abbreviation: MIS, minimally invasive surgery with fluoroscopy.
a
Surgeons 5 and 12, who had majority cases using intraoperative computed
tomography image-guided navigation, were excluded due to minimal fluoro-
scopy usage during those cases. Surgeons 1, 4, 6, 8,10, and 16 were excluded
due to having 2 or fewer total patients.
Wang et al 5
compared with robotic surgeries. This could possibly stem
from additional time required for setting up the IGN and
robotic systems, which has been reported to prolong operating
time.
3
However, other studies have reported that total-
procedure time is not significantly extended, despite a longer
setup time, because navigation allows for quicker placement of
pedicle screws.
30,31
In addition, a patient-level cost analysis
conducted by Dea et al
32
in 2016 reported a cost-effective
reduction in revision surgery for symptomatic postoperative
screw malposition using CT-based navigation. Taking all of
this into account, future comparison studies would be benefi-
cial and could incorporate cost data for a more complete picture
of cost-effectiveness.
Perhaps of more concern in this study is our findings on
radiation dosage. Because open procedures generally used min-
imal intraoperative fluoroscopy, the radiation doses for these
patients were predictably the lowest. More strikingly, radiation
dosage was highest for intraoperative, total-procedure and
total-procedure per level measurements in the fluoro-MIS
patient group. This is not necessarily a surprising finding, as
past studies have reported higher radiation exposure in less
invasive spine approaches.
23
However, the contrast in mean
dosage between the MIS group and both the IGN and robotic
groups is starker than one may expect. Mean total-procedure
radiation for the MIS cohort was 82.02 mGy compared with
50.21 mGy and 59.84 mGy in the IGN and robotic groups,
respectively (P< .001). The MIS patients also had the fewest
number of levels fused on average, so the difference was more
apparent when calculating total-procedure radiation per level
(79.41 mGy for MIS versus 41.88 mGy for IGN and 51.18 mGy
for robotic; P> .001). Despite the MIS patients having by far
the lowest rate of preoperative CT, which adds approximately
20 mGy of radiation to the total-procedure sum, they were still
exposed to substantially more radiation overall.
In assessing for differences in intraoperative fluoroscopy
time by different surgeons, we found no significant difference
between surgeons who primarily performed open and robotic
cases. There was, however, a greater variation in fluoroscopy
time among surgeons who performed majority MIS cases, with
2 surgeons in particular averaging over 100 seconds of fluoro-
scopy use per case while the others averaged in the 40- to 70-
second range (P¼.074). Because of the images being taken by
radiation technicians who wereusedbyallsurgeons,we
believe that this reflects some surgeons acquiring a larger num-
ber of images, rather than higher radiation dose per image.
Furthermore, the lower doses of radiation used by Surgeons 2
and 3 suggests that surgeon technique may help reduce radia-
tion doses in the MIS group.
While the aforementioned radiation measurements are for
the patient, because this radiation dose total stemmed primarily
from intraoperative fluoroscopy in MIS cases, it raises con-
cerns about the proportion of total radiation dose applied to
the surgeon and operating staff, who are performing these sur-
geries on a regular basis. Moreover, the surgeons are positioned
in closest proximity to intraoperative radiation scatter, whereas
for intraoperative CT or preoperative CT, they are not in close
proximity to the radiation source.
Radiation exposure in medicine is by no means benign. It
can lead to illness and injury in patients and surgeons alike and
is estimated to cause 0.6%to 3%of cancer cases worldwide.
33
There are currently no specific guidelines regarding radiation
exposure limits to surgeons and other operative room staff,
though there are general recommendations to minimize radia-
tion through various methods, such as the use of barriers and
other protective equipment.
34
Regardless of the system used for
guidance when placing pedicle screws, there should be an
attempt to maximize the configuration of imaging equipment
to achieve ALARA (as low as reasonably achievable) patient
radiation dose.
35
IGN and robotic assistance are still less uti-
lized at many institutions, with high costs and an involved
training process likely being primary prohibitive factors. None-
theless, these methods would likely expose both the patient and
the operative staff to significantly less radiation in nonopen
cases, compared with conventional fluoroscopic guidance,
without compromising perioperative outcomes. For this reason,
the judicious usage of IGN and robotic assistance could prove
to be advantageous, and this study suggests that further explo-
ration into their utilization is warranted.
Our study has some limitations. Because this was a retro-
spective cohort study, it has all of the accompanying limitations
of such a study. We also had a limited sample size, particularly
in the IGN group. Differences in intraoperative radiation expo-
sure may also be affected by the fact that procedures in differ-
ent groups were not all performed by the same surgical team.
Future studies could benefit from having a larger sample size as
more procedures are performed using these methods. A multi-
institutional study would also increase the sample size and may
reduce potential for surgeon technique and selection bias in
testing IGN and robotic guidance systems as well. Addition-
ally, further exploration into assessing occupational radiation
exposure with different methods of guidance would benefit this
conversation, as few studies have directly investigated radia-
tion exposure to surgeons and the rest of the operating room
staff themselves. In particular, further research involving data
collected from surgeon-worn dosimeters would better quantify
radiation dosage received in relation to fluoroscopy time. Nev-
ertheless, this study is, to our knowledge, the first to compare
patient radiation exposure between IGN, robotic assistance,
and conventional intraoperative fluoroscopic guidance in both
MIS and open TLIF surgeries. While there were no significant
differences in perioperative outcomes among groups, with the
exception of the expected lower EBL and LOS in MIS proce-
dures, further discussion about the costs and benefits of IGN
and robotic guidance systems are warranted, especially with
regard to radiation safety in comparison with conventional
fluoroscopy use.
Conclusion
Intraoperative CT IGN and robotic assistance in posterior lum-
bar fusion were associated with higher intraoperative and total-
6Global Spine Journal
procedure radiation exposure than open cases without IGN or
robotics; however, fluoroscopic-MIS has the highest total pro-
cedural radiation dose. While fluoroscopic-MIS procedures
reported highest radiation exposure to the patient, an additional
significant concern is that the proportion of total radiation dose
also applied to the surgeon and operating room staff in the
fluoroscopic-MIS group is much higher than that in IGN,
robotics, and open groups. More comprehensive or consistent
training for surgeons about fluoroscopy use may be beneficial
to reduce unnecessary intraoperative radiation exposure, par-
ticularly in MIS cases.
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to
the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, author-
ship, and/or publication of this article.
ORCID iD
Themistocles S. Protopsaltis, MD https://orcid.org/0000-0002-
4978-2600
Aaron J. Buckland, MBBS, FRACS https://orcid.org/0000-0002-
9424-0843
Ethical Approval
Each institution obtained approval from their local Institutional
Review Board to analyze or review patients in the retrospective data-
base. Waiver of consent was obtained from each patient.
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8Global Spine Journal
... Stephan Heisinger, MD 1 , Stefan Aspalter, MD 1 , and Josef G. Grohs, MD 1 The study published by Wang et al is highly interesting in our opinion and it highlights a crucial aspect of spinal surgery in terms of patient safety. 1 Furthermore, it is beyond all doubt essential to assess the radiation exposure of conventional fluoroscopy-guided surgery to robotic navigational guidance and intraoperative computed tomography (CT) image-guided navigation. As stated by Wang et al and shown by various authors, the application of these techniques yields improved accuracy of pedicle screw positioning. 1 However, there are some aspects of this study that need to be discussed, and we would like to compare our findings on radiation exposure in intraoperative computed tomography (iCT) versus fluoroscopy-assisted surgery to this study. ...
... Stephan Heisinger, MD 1 , Stefan Aspalter, MD 1 , and Josef G. Grohs, MD 1 The study published by Wang et al is highly interesting in our opinion and it highlights a crucial aspect of spinal surgery in terms of patient safety. 1 Furthermore, it is beyond all doubt essential to assess the radiation exposure of conventional fluoroscopy-guided surgery to robotic navigational guidance and intraoperative computed tomography (CT) image-guided navigation. As stated by Wang et al and shown by various authors, the application of these techniques yields improved accuracy of pedicle screw positioning. 1 However, there are some aspects of this study that need to be discussed, and we would like to compare our findings on radiation exposure in intraoperative computed tomography (iCT) versus fluoroscopy-assisted surgery to this study. ...
... As stated by Wang et al and shown by various authors, the application of these techniques yields improved accuracy of pedicle screw positioning. 1 However, there are some aspects of this study that need to be discussed, and we would like to compare our findings on radiation exposure in intraoperative computed tomography (iCT) versus fluoroscopy-assisted surgery to this study. 2 The authors reveal that in the open surgery fluoroscopyguided subgroup 1.32 + 0.47 levels were fused, and they stated that the fluoroscopy time of 3 surgeons who performed the majority of these cases ranged from 12.27 to 24.24 seconds per procedure. ...
... There has been recent debate regarding this radiation exposure and the safety of fluoroscopyguided orthopedic procedures. In the study by Wang et al. regarding posterior lumbar fusion, researchers expressed their apprehensions after discovering concerning radiation exposure to both patients and medical staff even during fluoroscopy-guided minimally invasive surgeries [9]. Several studies pertaining to the use of fluoroscopy-guided THA fail to assess radiation exposure or dose to which patients and surgical staff are subjected [10][11][12]. ...
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PurposeTo investigate the average fluoroscopy time, as well as the patient and surgical staff average radiation exposure in the context of intraoperative fluoroscopy use during anterior total hip arthroplasty (THA).Methods PubMed, Cochrane, Embase, Web of Science and Scopus were systematically searched for studies pertaining to intraoperative anterior THA fluoroscopy (PROSPERO ID 258049). The comprehensive literary search was conducted using “THA,” “fluoroscopy” and “radiation exposure” as the search criteria, which resulted in 187 total papers. Of these 187 papers, 11 studies were included in this systematic review as they involved anterior THA and specifically contained data regarding radiation exposure dose and/or time.ResultsEleven studies were included, enrolling 1839 patients. The average fluoroscopy time was 21.4 (95% confidence interval [CI] 16.6–26.1) seconds, whereas the average patient radiation dose was 1.8 × 10–3 (95% CI 7.4 × 10–4–2.9 × 10–3) Gy.Conclusions Although several studies fail to report fluoroscopy time and radiation dose in THA patients, fluoroscopy-guided THA has emerged as a safe procedure. Additional studies may analyze if radiation exposure during the surgeon’s THA learning curve is significantly higher, as well as what protocols may potentially reduce radiation exposure even further.
... Fluoroscopy had the highest radiation dosage (82.02 mGy) followed by robotic assistance (59.84 mGy) and CT image-guided navigation (50.21 mGy). This level of radiation exposure creates a potentially significant hazard to those individuals who perform a high volume of complex spinal surgery with fluoroscopy (4,5). ...
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The advancements in computing and digital localizer technologies has led to the evolving clinical application of image-guided technology for the surgical management of spinal disorders. Image-guided spinal navigation addresses the limitations of fluoroscopy and improves the accurate placement of fixation screws. Several navigation platforms are currently available, each having its own unique advantages and disadvantages. The most recent spinal navigation system developed utilizes machine vision structured light imaging which creates a precise and detailed three-dimensional image of the exposed surface anatomy and co-registers it to a pre-operatively or intra-operatively acquired image. This system improves upon the intraoperative workflow and efficiency of the navigation process. With the continued advancements in machine vision, there is a potential for clinical applications that extend beyond surgical navigation. These applications include reducing the potential for wrong level spine surgery and providing for real-time tracking of spinal deformity correction. As the adoption and clinical experience with navigation continues to expand and evolve, the technology that enables navigation also continues to evolve.
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Robotic-assisted adult deformity surgery has played a rapidly expanding role since its introduction. As robotic spine technologies improve, the potential to limit complications and morbidity is vast. The improvements in instrumentation accuracy combined with the ability to maintain that accuracy in multiple positions allow creative surgical approaches and techniques that can limit operative time, blood loss, and improve outcomes. In the years to come, robotic-assisted spine surgery and navigation will likely play an expanding role that continues to be defined. LEVEL OF EVIDENCE: 5, expert opinion.
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Background context The use of spinal image guidance systems (IGS) has increased patient safety, accuracy, operative efficiency, and reduced revision rates in pedicle screw placement procedures. Traditional intraoperative 3D fluoroscopy or CT imaging produces potentially harmful ionizing radiation and increases operative time to register the patient. An IGS, FLASH Navigation, uses machine vision through high resolution stereoscopic cameras and structured visible light to build a 3D topographical map of the patient's bony surface anatomy enabling navigation use without ionizing radiation. Purpose We aimed to compare FLASH navigation system to a widely used 3D fluoroscopic navigation (3D) platform by comparing radiation exposure and pedicle screw accuracy. Design A randomized prospective comparative cohort study of consecutive patients undergoing open posterior lumbar instrumented fusion. Patient Sample Adults diagnosed with spinal pathology requiring surgical treatment and planning for open posterior lumbar fusion with pedicle screws implanted into 1-4 vertebral levels. Outcome measures Outcome measures included mean intraoperative fluoroscopy time and dose, mean CT dose length product (DLP) for preoperative and day 2 CT, pedicle screw accuracy by CT, estimated blood loss and revision surgery rate. Methods Consecutive patients were randomized 1:1 to FLASH or 3D and underwent posterior lumbar instrumented fusion. Radiation doses were recorded from pre- and postoperative CT and intraoperative 3D fluoroscopy. Two independent blinded radiologists reviewed pedicle screw accuracy on CT. Results A total of 429 (n=210 FLASH, n=219 3D) pedicle screws were placed in 90 patients (n=45 FLASH, n=45 3D) over the 18-month study period. Mean age and indication for surgery were similar between both groups, with a non-significantly higher ratio of males in the 3D group. Mean intraoperative fluoroscopy time and doses were significantly reduced in FLASH compared to 3D (4.51±3.71s vs 79.6±23.0s, p<0.001 and 80.9±68.1cGycm² vs 3704.1±3442.4 cGycm², p<0.001, respectively). This represented a relative reduction of 94.3% in the total intraoperative radiation time and a 97.8% reduction in the total intraoperative radiation dose. Mean preoperative CT DLP and mean day 2 postoperative CT DLP were significantly reduced in FLASH compared to 3D (662.0±440.4mGy-cm vs 1008.9±616.3 mGy-cm, p<0.001 and 577.9±294.3 mGy-cm vs 980.7±441.6 mGy-cm, p<0.001, respectively). This represented relative reductions of 34.4% and 41.0% in the preoperative CT dose and postoperative total DLP, respectively. The FLASH group required an average of 1.2 registrations in each case with an average of 2447 (±961.3) data points registered with a mean registration time of 106s (±52.1). A rapid re-registration mechanism was utilized in 22% (n=10/45) of cases and took 22.7s (±11.3). Re-registration was used in 7% (n=3/45) in the 3D group. Pedicle screw accuracy was high in FLASH (98.1%) and 3D (97.3%) groups with no pedicle breach >2mm in either group (p<0.001). EBL was not statistically different between the groups (p=0.38). No neurovascular injuries occurred, and no patients required return to theatre for screw repositioning. Conclusions FLASH and 3D IGS demonstrate high accuracy for pedicle screw placement. FLASH showed significant reduction in intraoperative radiation time and dose with lower but non-significant blood loss. FLASH showed significant reduction in preoperative and postoperative radiation, but this may be associated to the lower number of males/females preponderance in this group. FLASH provides similar accuracy to contemporary IGS without requiring 3D-fluoroscopy or radiolucent operating tables. Reducing registration time and specialized equipment may reduce costs.
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Background context Anterior Lumbar Interbody Fusion (ALIF) and Lateral Lumbar Interbody Fusion (LLIF) with percutaneous posterior screw fixation are two techniques used to address degenerative lumbar pathologies. Traditionally, these anterior-posterior (AP) surgeries involve repositioning the patient from the supine or lateral decubitus position to prone for posterior fixation. To reduce operative time (OpTime) and subsequent complications of prolonged anesthesia, single-position lumbar surgery (SPLS) is a novel, minimally invasive alternative performed entirely from the lateral decubitus position. Purpose Assess the perioperative safety and efficacy of single position anterior-posterior lumbar fusion surgery (SPLS). Study design Multi-center retrospective cohort study. Patient sample 390 patients undergoing AP surgery were included, of which 237 underwent SPLS and 153 were in the Flip group. Outcome measures Outcome measures included levels fused, percentage of cases including L5-S1 fusion, fluoroscopy radiation dosage, OpTime, estimated blood loss (EBL), length of stay (LOS), and perioperative complications. Radiographic analysis included lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), and segmental lumbar lordosis. Methods Patients undergoing primary ALIF and/or LLIF surgery with bilateral percutaneous pedicle screw fixation between L2-S1 were included over a 4-year period. Patients were classified as either traditional repositioned “Flip” surgery or SPLS. Outcome measures included levels fused, percentage of cases including L5-S1 fusion, fluoroscopy radiation dosage, OpTime, EBL, LOS, perioperative complications. Radiographic analysis included lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), and segmental lumbar lordosis. All measures were compared using independent samples t-tests and chi-squared analyses as appropriate with significance set at p<0.05. Propensity matching was completed where demographic differences were found. Results 390 patients undergoing AP surgery were included, of which 237 underwent SPLS and 153 were in the Flip group. Age, gender, BMI, CCI were similar between groups. Levels fused (1.47 SPLS vs 1.52 Flip, p=0.468) and percent cases including L5-S1 (31% SPLS, 35% Flip, p=0.405) were similar between cohorts. SPLS significantly reduced OpTime (103min vs 306min, p<0.001), EBL (97 vs 313ml, p<0.001), LOS (1.71 vs 4.12 days, p<0.001), and fluoroscopy radiation dosage (32 vs 88mGy, p<0.001) compared to Flip. Perioperative complications were similar between cohorts with the exception of postoperative ileus, which was significantly lower in the SPLS group (0% vs 5%, p<0.001). There was no significant difference in wound, vascular injury, neurological complications, or VTE. There was no significant difference found in 90 day return to OR. Conclusions SPLS improves operative efficiency in addition to reducing blood loss, length of stay and ileus in this large cohort study, while maintaining safety.
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Careful protocol selection is required during intraoperative three‐dimensional (3D) imaging for spine surgery to manage patient radiation dose and achieve clinical image quality. Radiation dose and image quality of a Medtronic O‐arm commonly used during spine surgery, and a Philips hybrid operating room equipped with XperCT C‐arm 3D cone‐beam CT (hCBCT) are compared. The mobile O‐arm (mCBCT) offers three different radiation dose settings (low, standard, and high), for four different patient sizes (small, medium, large, and extra large). The patient's radiation dose rate is constant during the entire 3D scan. In contrast, C‐CBCT spine imaging uses three different field of views (27, 37, and 48 cm) using automatic exposure control (AEC) that modulates the patient's radiation dose rate during the 3D scan based on changing patient thickness. hCBCT uses additional x‐ray beam filtration. Small, medium, and large trunk phantoms designed to mimic spine and soft tissue were imaged to assess radiation dose and image quality of the two systems. The estimated measured “patient” dose for the small, medium, and large phantoms imaged by the mCBCT considering all the dose settings ranged from 9.4–27.6 mGy, 8.9–33.3 mGy, and 13.8–40.6 mGy, respectively. The “patient” dose values for the same phantoms imaged with hCBCT were 2.8–4.6 mGy, 5.7–10.0 mGy, and 11.0–15.2 mGy. The CNR for the small, medium, and large phantoms was 2.9 to 3.7, 2.0 to 3.0, and 2.5 to 2.6 times higher with the hCBCT system, respectively. Hounsfield unit accuracy, noise, and uniformity of hCBCT exceeded the performance of the mCBCT; spatial resolution was comparable. Added x‐ray beam filtration and AEC capability achieved clinical image quality for intraoperative spine surgery at reduced radiation dose to the patient in comparison to a reference O‐arm system without these capabilities.
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Introduction. A new generation of iCT scanner, Airo®, has been introduced. The purpose of this study is to describe how Airo facilitates minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF). Method . We used the latest generation of portable iCT in all cases without the assistance of K-wires. We recorded the operation time, number of scans, and pedicle screw accuracy. Results . From January 2015 to December 2015, 33 consecutive patients consisting of 17 men and 16 women underwent single-level or two-level MIS-TLIF operations in our institution. The ages ranged from 23 years to 86 years (mean, 66.6 years). We treated all the cases in MIS fashion. In four cases, a tubular laminectomy at L1/2 was performed at the same time. The average operation time was 192.8 minutes and average time of placement per screw was 2.6 minutes. No additional fluoroscopy was used. Our screw accuracy rate was 98.6%. No complications were encountered. Conclusions . Airo iCT MIS-TLIF can be used for initial planning of the skin incision, precise screw, and cage placement, without the need for fluoroscopy. “Total navigation” (complete intraoperative 3D navigation without fluoroscopy) can be achieved by combining Airo navigation with navigated guide tubes for screw placement.
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Although application of intraoperative computer navigation technique had been integrated into placement of pedicle screws (PSs) in thoracic fusion for years, its security and practicability remain controversial. The aim of this study is to evaluate the accuracy, the operative time consumption, the amount of intraoperative blood loss, time of pedicle insertion and the incidence of complications of thoracic pedicle screw placement in patients with thoracic diseases such as scoliosis and kyphosis. Pubmed, Web of Knowledge, and Google scholar were searched to identify comparative studies of thoracic pedicle screw placement between intraoperative computer navigation and fluoroscopy-guided navigation. Outcomes of malposition rate, operative time consumption, insertion time, intraoperative blood loss, and the incidence of complications are evaluated. Fourteen articles including 1723 patients and 9019 PSs were identified matching inclusion criteria. The malposition rate was lower (RR: 0.33, 95 % CI: 0.28-0.38, P < 0.01) in computer navigation group than that in fluoroscopy-guided navigation group; the operative time was significantly longer [weighted mean difference (WMD) = 23.66, 95 % CI: 14.74-32.57, P < 0.01] in computer navigation group than that in fluoroscopy-guided navigation group. The time of insertion was shorter (WMD = -1.88, 95 % CI: -2.25- -1.52, P < 0.01) in computer navigation group than that in fluoroscopy-guided navigation group. The incidence of complications was lower (RR = 0. 23, 95 % CI: 0.12-0.46, P < 0.01) in computer navigation group than that in the other group. The intraoperative blood loss was fewer (WMD = -167.49, 95 % CI: -266.39- -68.58, P < 0.01) in computer navigation group than that in the other. In conclusion, the meta-analysis of thoracic pedicle screw placement studies clearly demonstrated lower malposition rate, less intraoperative blood loss, and fewer complications when using computer navigation. This result provides strong evidence that computer technology could be safer and more reliable than fluoroscopy-guided navigation.
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Computer-navigated pedicle screw insertion is applied to the thoracic and lumbar spine to attain high insertion accuracy and a low rate of screw-related complications. However, some in vivo and in vitro studies have shown that no advantages are gained with the use of navigation techniques compared to conventional techniques. Additionally, inconsistent conclusions have been drawn in various studies due to different population characteristics and methods used to assess the accuracy of screw placement. Moreover, it is not clear whether pedicle screw insertion with navigation techniques decreases the incidence of screw-related complications. Therefore, this study was sought to perform a meta-analysis of all available prospective evidence regarding pedicle screw insertion with or without navigation techniques in human thoracic and lumbar spine. We considered in vivo comparative studies that assessed the results of pedicle screw placement with or without navigation techniques. PubMed, Ovid MEDLINE and EMBASE databases were searched. Three published randomized controlled trials (RCTs) and nine retrospective comparative studies met the inclusion criteria. These studies included a total of 732 patients in whom 4,953 screws were inserted. In conclusion, accuracy of the position of grade I, II, III and IV screws and complication rate related to pedicle screw placement were significantly increased when navigation techniques were used in comparison to conventional techniques. Future research in this area should include RCTs with well-planned methodology to limit bias and report on validated, patient-based outcome measures.
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Objective: Pedicle screw placement remains challenging. The present study focuses on the comparison between 2 intraoperative-based neuronavigation systems (O-Arm and AIRO) during thoracolumbar screw instrumentation. Methods: This is a prospective, comparative, nonrandomized study conducted in 2 French academic centers. The O-Arm was used at the University Hospital of Bordeaux, whereas the AIRO was used at the University Hospital of Marseille. Routine computed tomography was performed on postoperative day 2 to evaluate pedicle screw placement. Measures of radiation exposure were extracted directly from reports provided by each system. The effective dose was calculated. Results: Overall, 74 screws were placed in 11 patients in the O-Arm group and 84 in 11 patients in the AIRO group. In the first group, 90.8% were rated as acceptable and 92.2% in the second (P > 0.05) according to the Heary and Gertzbein classifications, respectively, for thoracic and lumbar spine. Differences between both implantation systems were significant (P < 0.05) concerning dose length product (235 and 1039 mGy/cm, in O-Arm and AIRO, respectively), overall mean radiation dose received by 1 patient (3.52 and 15.6 mSv in O-Arm and AIRO, respectively), mean radiation dose per single scan (2.58 and 8.7 mSv in O-Arm and AIRO, respectively), mean effective dose per instrumented level (1.04 and 3.9 mSv in O-Arm and AIRO, respectively), and radiation dose received by the primary surgeon (0.63 and 0 μSv in O-Arm and AIRO, respectively). Conclusions: Intraoperative computed tomography-based navigation is a major innovation that improves the accuracy of pedicle screw positioning with acceptable patient radiation exposure and reduced surgical team exposure.
Article
Background Context: Imaging modalities used to visualize spinal anatomy intraoperatively include x-rays, fluoroscopy, and computed tomography (CT). All of these emit ionizing radiation. Purpose: Radiation emitted to the patient and the surgical team when performing surgeries using intraoperative CT-based spine navigation was compared. Study Design/Setting: This is a retrospective cohort case-control study. Patient Sample: Seventy-three patients underwent CT-navigated spinal instrumentation and 73 matched controls underwent spinal instrumentation with conventional fluoroscopy. Outcome Measures: Effective doses of radiation to the patient when the surgical team was inside and outside of the room were analyzed. The number of postoperative imaging investigations between navigated and non-navigated cases was compared. Methods: Intraoperative x-rays, fluoroscopy, and CT dosages were recorded and standardized to effective doses. The number of postoperative imaging investigations was compared with the matched cohort of surgical cases. A literature review identified historical radiation exposure values for fluoroscopic-guided spinal instrumentation. Results: The 73 navigated operations involved an average of 5.44 levels of instrumentation. Thoracic and lumbar instrumentations had higher radiation emission from all modalities (CT, x-ray, and fluoroscopy) compared with cervical cases (6.93 millisievert [mSv] vs. 2.34 mSv). Major deformity and degenerative cases involved more radiation emission than trauma or oncology cases (7.05 mSv vs. 4.20 mSv). On average, the total radiation dose to the patient was 8.7 times more than the radiation emitted when the surgical team was inside the operating room. Total radiation exposure to the patient was 2.77 times the values reported in the literature for thoracolumbar instrumentations performed without navigation. In comparison, the radiation emitted to the patient when the surgical team was inside the operating room was 2.50 lower than non-navigated thoracolumbar instrumentations. The average total radiation exposure to the patient was 5.69 mSv, a value less than a single routine lumbar CT scan (7.5 mSv). The average radiation exposure to the patient in the present study was approximately one quarter the recommended annual occupational radiation exposure. Navigation did not reduce the number of postoperative x-rays or CT scans obtained. Conclusions: Intraoperative CT navigation increases the radiation exposure to the patient and reduces the radiation exposure to the surgeon when compared with values reported in the literature. Intraoperative CT navigation improves the accuracy of spine instrumentation with acceptable patient radiation exposure and reduced surgical team exposure. Surgeons should be aware of the implications of radiation exposure to both the patient and the surgical team when using intraoperative CT navigation.
Article
Background context: Pedicle screws are routinely used in contemporary spinal surgery. Screw misplacement may be asymptomatic, but is also correlated with potential adverse events. Computer assisted surgery has been associated with improved screw placement accuracy rates. However, this technology has substantial acquisition and maintenance costs. Despite its increasing usage, no rigorous full economic evaluation comparing this technology to current standard of care has been reported. Purpose: Medical costs are exploding in a unsustainable way. Health economic theory requires that medical equipment costs be compared to expected benefits. To answer this question for computer assisted spinal surgery, we present an economic evaluation looking specifically at symptomatic misplaced screws leading to reoperation secondary to neurological deficits or biomechanical concerns. Study design/setting: Observational case-control study from prospectively collected data of consecutive patients treated with the aid of computer-assisted surgery (treatment group) compared to a matched historical cohort of patients treated with conventional fluoroscopy (control group). Patient sample: Consecutive patients treated surgically at a quaternary academic center. Outcome measures: The primary effectiveness measure studied was the number of reoperations for misplaced screws within one year of the index surgery. Secondary outcome measures included were: total adverse event rate and post-operative CT usage for pedicle screw examination. Methods: A patient-level data cost-effectiveness analysis from the hospital perspective was conducted to determine the value of a navigation system coupled with intra-operative 3D imaging (O-arm® Imaging and the StealthStation® S7 Navigation Systems, Medtronic, Louisville, CO) in adult spinal surgery. The capital costs for both alternatives were reported as equivalent annual costs based on the annuitization of capital expenditures method using a 3% discount rate and a 7-year amortization period. Annual maintenance costs were also added. Finally, reoperation costs using a micro-costing approach were calculated for both groups. An incremental cost-effectiveness ratio was calculated and reported as cost per reoperation avoided. Based on reoperation costs in Canada and in the US, a minimal caseload was calculated for the more expensive alternative to be cost saving. Sensitivity analyses were also conducted. Results: A total of 5132 pedicle screws were inserted in 502 patients during the study period, 2682 screws in 253 patients in the treatment group and 2450 screws in 249 patients in the control group. Overall accuracy rates were 95.2% for the treatment group and 86.9% for the control group. Within one year post treatment, two patients (0.8%) required a revision surgery in the treatment group compared to 15 patients (6%) in the control group. An incremental cost effectiveness ratio of $15,961/reoperation avoided was calculated for the computer-assisted surgery group. Based on a reoperation cost of $12,618, this new technology becomes cost-saving for centers performing more than 254 instrumented spinal procedures per year. Conclusion: Computer-assisted spinal surgery has the potential to reduce reoperation rates and thus to have serious cost-effectiveness and policy implications. High acquisition and maintenance costs of this technology can be offset by equally high reoperation costs. Our cost-effectiveness analysis showed that for high-volume centers with a similar case complexity to the studied population, this technology is economically justified.
Article
Background context: Imaging modalities used to visualize spinal anatomy intraoperatively include x-rays, fluoroscopy and CT. All emit ionizing radiation. Purpose: Radiation emitted to the patient and the surgical team when performing surgeries using intraoperative CT-based spine navigation were compared. Study design/setting: Retrospective cohort case-control study. Patient sample: 73 patients underwent CT navigated spinal instrumentation and 73 matched controls underwent spinal instrumentation with conventional fluoroscopy. Outcome measures: Effective doses of radiation to the patient when the surgical team was inside and outside of the room were analyzed. Number of postoperative imaging investigations between navigated and non-navigated cases were compared. Methods: Intraoperative x-rays, fluoroscopy and CT dosages were recorded and standardized to effective doses. The number of postoperative imaging investigations was compared with the matched cohort of surgical cases. A literature review identified historical radiation exposure values for fluoroscopic-guided spinal instrumentation. Results: The 73 navigated operations involved an average of 5.44 levels of instrumentation. Thoracic and lumbar instrumentations had higher radiation emission from all modalities (CT, X-ray, fluoroscopy) compared to cervical cases (6.93 mSv vs. 2.34 mSv). Major deformity and degenerative cases involved more radiation emission than trauma or oncology cases (7.05 mSv vs. 4.20 mSv). On average, the total radiation dose to the patient was 8.7 times more radiation than the radiation emitted when the surgical team was inside the operating room. Total radiation exposure to the patient was 2.77 times the values reported in the literature for thoracolumbar instrumentations performed without navigation. In comparison, the radiation emitted to the patient when the surgical team was inside the operating room was 2.50 lower than non-navigated thoracolumbar instrumentations. The average total radiation exposure to the patient was 5.69 mSv, a value less than a single routine lumbar CT scan (7.5 mSv). The average radiation exposure to the patient in this study was approximately one quarter the recommended annual occupational radiation exposure. Navigation did not reduce the number of postoperative x-rays or CT scans obtained. Conclusions: Intraoperative CT navigation increases the radiation exposure to the patient and reduces the radiation exposure to the surgeon when compared to values reported in the literature. Intraoperative CT navigation improves the accuracy of spine instrumentation with acceptable patient radiation exposure and reduced surgical team exposure. Surgeons should be aware of the radiation exposure implications to both the patient and the surgical team when using intraoperative CT navigation.
Article
Study Design. In vitro evaluation of monitoring screw placement using an image-guided system compared with the routine use of an image intensifier. Objectives. To compare a new computer-guided method of monitoring pedicle screw placement with a well-known method of monitoring using an image intensifier, using measurements of screw placement time and accuracy. Summary of Background Data. Pedicle screw placement relies on the identification of anatomic landmarks for the point of entry of the pedicle. The direction and depth of screw penetration are guided by an intraoperative lateral-view image intensifier. The use of frameless stereotaxy for computer-aided pedicle screw placement may increase the accuracy and safety of the screw insertion. To the authors’ knowledge, there are no published data comparing these systems on the basis of operative time and screw placement accuracy. Method. Eight human cadaveric sections of five vertebrae each were used for an in vitro simulation of pedicle screw placement. Four spine surgeons were chosen to simulate the transpedicular screw placement. Each surgeon placed one screw into each pedicle of two spine sections (10 vertebrae, 20 screws). The surgeon was assisted by the lateral-view image intensifier on one spine section and by the navigational system on the second one. The four surgeons placed 80 pedicle screws. Forty screw placements were monitored by fluoroscopy and 40 by the image-guided navigational system. The time spent to place one screw was recorded, as well as the remarks by each surgeons on each method. Spines were rescanned, and the positions of the screws were compared between the group on which the image intensifier has been used and the group on which the navigational system had been used. Results. In the image-guided technique group, one thoracic screw disrupted the lateral cortex of the pedicle, the average distance to the anterior wall of the body was 5 mm, and the average time for the insertion of one screw was 13.5 minutes. In the other group, two screws disrupted the inner cortex of a thoracic pedicle, the average distance to the anterior wall was 10.7 mm, and the average time for the insertion of one screw was 4 minutes. Conclusions. In vitro computer-aided pedicle screw insertion is more accurate than lateral-view fluoroscopy in the thoracic spine. The main disadvantage is the time consumption compared with that required by lateral-view fluoroscopy. The total time of the surgical operation should be decreased with the future development of these techniques.
Article
Radiation exposure to patients and spine surgeons during spine surgery is expected. The risks of radiation exposure include thyroid cancer, cataracts, and lymphoma. Although imaging techniques facilitate less invasive approaches and improve intraoperative accuracy, they may increase radiation exposure. We performed a systematic review to determine whether (1) radiation exposure differs in open spine procedures compared with less invasive spine procedures; (2) radiation exposure differs in where the surgeon is positioned in relation to the C-arm; and (3) if radiation exposure differs using standard C-arm fluoroscopy or fluoroscopy with computer-assisted navigation. A PubMed search was performed from January 1980 to July 2013 for English language articles relating to radiation exposure in spine surgery. Twenty-two relevant articles met inclusion criteria. Level of evidence was assigned on clinical studies. Traditional study quality evaluation of nonclinical studies was not applicable. There are important risks of radiation exposure in spine surgery to both the surgeon and patient. There is increased radiation exposure in less invasive spine procedures, but the use of protective barriers decreases radiation exposure. Where the surgeon stands in relation to the image source is important. Increasing the distance between the location of the C-arm radiation source and the surgeon, and standing contralateral from the C-arm radiation source, decreases radiation exposure. The use of advanced imaging modalities such as CT or three-dimensional computer-assisted navigation can potentially decrease radiation exposure. There is increased radiation exposure during less invasive spine surgery, which affects the surgeon, patient, and operating room personnel. Being cognizant of radiation exposure risks, the spine surgeon can potentially minimize radiation risks by optimizing variables such as the use of barriers, knowledge of position, distance from the radiation source, and use of advanced image guidance navigation-assisted technology to minimize radiation exposure. Continued research is important to study the long-term risk of radiation exposure and its relationship to cancer, which remains a major concern and needs further study as the popularity of less invasive spine surgery increases.