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ORIGINAL ARTICLE
Six-month outcomes from a randomized controlled trial
of minimally invasive SI joint fusion with triangular titanium
implants vs conservative management
Bengt Sturesson
1
•Djaya Kools
2
•Robert Pflugmacher
3
•Alessandro Gasbarrini
4
•
Domenico Prestamburgo
5
•Julius Dengler
6
Received: 21 January 2016 / Revised: 28 April 2016 / Accepted: 29 April 2016 / Published online: 14 May 2016
ÓThe Author(s) 2016. This article is published with open access at Springerlink.com
Abstract
Purpose To compare the safety and effectiveness of min-
imally invasive sacroiliac joint fusion (SIJF) using trian-
gular titanium implants vs conservative management (CM)
in patients with chronic sacroiliac joint (SIJ) pain.
Methods 103 adults with chronic SIJ pain at nine sites in
four European countries were randomly assigned to and
underwent either minimally invasive SIJF using triangular
titanium implants (N=52) or CM (N=51). CM was
performed according to the European guidelines for the
diagnosis and management of pelvic girdle pain and con-
sisted of optimization of medical therapy, individualized
physical therapy (PT) and adequate information and reas-
surance as part of a multifactorial treatment. The primary
outcome was the difference in change in self-rated low
back pain (LBP) at 6 months. Additional endpoints inclu-
ded quality of life using EQ-5D-3L, disability using
Oswestry Disability Index (ODI), SIJ function using active
straight leg raise (ASLR) test and adverse events.
NCT01741025.
Results At 6 months, mean LBP improved by 43.3 points
in the SIJF group and 5.7 points in the CM group (differ-
ence of 38.1 points, p\0.0001). Mean ODI improved by
26 points in the SIJF group and 6 points in the CM group
(p\0.0001). ASLR, EQ-5D-3L, walking distance and
satisfaction were statistically superior in the SIJF group.
The frequency of adverse events did not differ between
groups. One case of postoperative nerve impingement
occurred in the surgical group.
Conclusions In patients with chronic SIJ pain, minimally
invasive SIJF using triangular titanium implants was safe
and more effective than CM in relieving pain, reducing
disability, improving patient function and quality of life.
Keywords Sacroiliac joint dysfunction Pelvic girdle
pain Sacroiliac joint fusion Titanium sacroiliac implant
Randomized controlled trial Conservative management
iFuse Implant System
Introduction
Pain from the sacroiliac joint (SIJ) was first described in
the 1800s [1]. Often described as a form of pelvic girdle
pain (PGP), SIJ pain was believed to be the major source of
low back pain (LBP) in the early twentieth century [2,3].
The discovery of disc herniation in the 1930s [4] turned the
focus from the SIJ to the intervertebral disc as a pain
source. Since treatment of disc pathology does not always
result in LBP relief, interest has resurfaced in the SIJ as
potential source of LBP. Recently several reports estimate
that 15–30 % of LBP is caused by the SIJ [5,6]. The SIJ
The members of iMIA Study Investigators/study coordinators are
listed in ‘‘Appendix’’ .
&Bengt Sturesson
sturesson.bengt@gmail.com
1
Department of Orthopedics, Aleris, A
¨ngelholm Hospital,
A
¨ngelholm, Sweden
2
Department of Neurosurgery, Onze-Lieve-Vrouw Hospital
Aalst, Aalst, Belgium
3
Department of Orthopedics and Traumatology, University
Hospital Bonn, Bonn, Germany
4
Instituto Ortopedico Rizzoli di Bologna, Bologna, Italy
5
Department of Orthopedics and Traumatology, ASST Ovest
Milanese, Ospedale di Legnano, Legnano, Italy
6
Department of Neurosurgery, Charite
´, Universitaetsmedizin
Berlin, Berlin, Germany
123
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DOI 10.1007/s00586-016-4599-9
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may be an even more common pain source after lumbar
fusion [7,8].
LBP is an important socioeconomic problem, increasing
the risk of early retirement and poverty in patients older
than 45 years [9]. Although conservative management
(CM) remains the first-line treatment for SIJ pain, a sig-
nificant number of patients do not respond well, resulting in
unremitting pain. The innervation, movement and eluci-
dation of basic biomechanics [10–12] of the SIJ justify its
treatment with sacroiliac joint fusion (SIJF). Approaches to
SIJF were reported as early as the 1920s [13,14] and case
series of open SIJF report modest to good effectiveness
[15–19]. However, open surgery is demanding for both the
surgeon and patient since it results in substantial blood loss,
pain and morbidity from soft tissue disruption, and a high
frequency of non-union [16,19,20]. Therefore, minimally
invasive techniques [21], which can also be performed
percutaneously [22], were developed to reduce postopera-
tive morbidity while maintaining or improving upon
effectiveness. Some comparative studies suggest that
minimally invasive strategies may be superior to open
strategies [23–25]. Herein, we present the first prospective
multicenter European study comparing the safety and
effectiveness of minimally invasive SIJF using triangular
titanium implants vs CM for patients with chronic SIJ pain.
Methods
iFuse Implant System Minimally Invasive Arthrodesis
(iMIA, NCT01741025) is an ongoing prospective, open-
label, multicenter randomized controlled trial. Enrollment
took place between June 2013 and May 2015 at 9 spine
care clinics in Europe. The clinical investigational plan was
approved by all relevant ethics committees prior to first
patient enrollment and all study data were 100 % source
verified.
Patient population
The target patient population was adults with chronic,
disabling SI joint pain unrelated to acute trauma or
underlying inflammatory disease. Patients were between 21
and 70 years old, had LBP for [6 months (or [18 months
for pregnancy-related pain), were diagnosed with the SI
joint as the primary pain generator based on the following 3
criteria: (1) pain was present at or close to the posterior
superior iliac spine (PSIS) and patient could point with a
single finger to the location of pain (Fortin Finger Test
[26]), (2) at least 3 positive findings on 5 provocative
physical examination maneuvers for SIJ pain, and (3) at
least 50 % pain reduction on fluoroscopically guided
injection of local anesthetic into the joint (SIJ block).
Examples of physical examination maneuvers for SIJ pain
are shown in Fig. 1. The predictive value of physical
examination maneuvers for a positive SI joint block is
fairly high, especially when multiple physical examination
tests are positive [27].
Enrollment also required a baseline Oswestry Disability
Index [28] (ODI) score of at least 30 %, a baseline LBP
visual analog score (VAS) of at least 50 (0–100 scale) and
signed consent form. Key exclusion criteria included:
severe LBP due to other causes, autoimmune sacroiliitis,
recent pelvic trauma, spine surgery in the last 12 months,
diagnosed or suspected osteoporosis and allergy to
titanium.
Randomization and masking
Subjects were assigned at random in a 1:1 ratio after eli-
gibility and baseline assessments by study coordinators
using a password-protected web site. Randomization
sequences were computer-generated using a random num-
ber generator. We used a stratified randomization process
that was stratified by both site and pregnancy as a cause of
SIJ pain. Subjects and researchers were not blinded to
treatment.
Interventions
Conservative management was designed according to the
European guidelines for the diagnosis and management of
pelvic girdle pain [29]. CM consisted of (1) optimization of
medical therapy, (2) individualized physical therapy (PT)
that focused on mobilization and stabilization exercises for
control and stability, and (3) adequate information and
reassurance of the patient as part of a multifactorial treat-
ment. CM subjects were asked to undergo PT sessions at
least twice per week for up to 8 weeks. The protocol
allowed cognitive behavioral therapy (CBT) as part of CM,
but this was not available at all sites and no high quality
evidence suggests that it is effective in chronic SIJ pain. The
protocol specifically noted that interventional procedures
(e.g., SI joint steroid injections, radiofrequency ablation of
lateral branches of sacral nerve roots) are not part of CM.
Minimally invasive SIJF was performed using
iFuse Implant System
Ò
(SI-BONE, Inc., San Jose, CA,
USA) as described previously [30]. The device system is
CE marked for SIJF. Subjects requiring treatment of both
SI joints could undergo staged procedures. To reduce SI
joint micromotion or rotation after surgery, the implant is
designed in a triangular shape for interference fit and
immediate joint stabilization. For the first 3 weeks after
surgery patients were kept at heel-toe touchdown weight-
bearing which was then increased until patients were fully
ambulatory.
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Follow-up
Subjects underwent in-clinic follow-up visits at 1, 3 and
6 months (study visits continue to 2 years after treatment
initiations). Follow-up assessments consisted of LBP VAS,
ODI, active straight leg raise test (ASLR) [31], EQ-5D
[32], and self-rated assessments of satisfaction, desirability
of having the same intervention again, overall pain levels
and walking distance, and a review of adverse events (per
ISO 14155:2011). According to the study protocol, subjects
assigned to CM were allowed to cross over from CM to
surgical care after the month 6 visit was complete.
Study endpoints, cohorts and statistical analysis
The study’s primary endpoint was the change in LBP VAS
score at 6 months after the most recent SIJF (to accom-
modate subjects with staged bilateral surgery) or start of
CM. A modified intent-to-treat cohort was used for statis-
tical analysis, which includes all enrolled subjects who
underwent the assigned study treatment. A sample size of
40 subjects per group had 80 % power to detect a differ-
ence of 20 points in VAS SIJ pain assuming a standard
deviation (SD) of 35 points. The sample size was inflated to
50 subjects per group to account for potential loss to fol-
low-up. There were no interim stopping plans. The primary
analysis used a general linear model that adjusted for
pregnancy-relatedness as a randomizing stratification
variable. According to the statistical analysis plan, missing
data for the primary endpoint were to be imputed using
regression methods if the missing data rate exceeded 5 %.
Additional analyses, including multivariate analyses, were
used to examine center-level effects and the effect of
potential confounders. Poolability was assessed by com-
paring treatment effects across sites. No changes to the
statistical analysis plan were made post hoc.
Secondary endpoints included change from baseline in
the following: LBP VAS at other time points, ASLR for the
affected side, ODI, and EQ-5D, walking distance, and
adverse events. Age and sex norms for EQ-5D were taken
from Ko
¨nig et al. [33] and values in the current trial were
compared with those from the Swedish Spine Registry
[34]. Continuous endpoints were compared using methods
similar to the primary endpoint using all available data.
Ordinal endpoints were examined using logistic or pro-
portional odds logistic regression. Analysis of procedure-
related variables focused on the index (first side) procedure
only. We used Poisson regression to examine the number
of adverse events per subject. No adjustment for multi-
plicity was performed. All statistical analyses were per-
formed using R[35].
Results
Enrollment
109 subjects were enrolled in 4 countries (31 from Bel-
gium, 45 from Germany, 21 from Italy and 12 from Swe-
den) between June 2013 and May 2015, of whom 6 (4
Fig. 1 Physical examination tests for SI joint pain. aLong ligament test, bFABER, ccompression, dO
¨stgaard test (thigh thrust), eGaenslen’s
test, factive straight leg raise test
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assigned to CM, 2 to SIJF) withdrew prior to receiving any
intervention. 4 subjects (all at one site) were enrolled
despite having inadequate acute pain relief after SIJ block.
As these subjects underwent study treatment, they were
included in all analyses.
Table 1shows demographic characteristics of the 103
participating subjects. Mean age was 48.1 years and 75
subjects (72.8 %) were women. 39 (37.9 %) were current
smokers. Most subjects experienced SIJ pain during vari-
ous activities (Table 1) and mean duration of SIJ pain was
4.7 years. Most (72.8 %) had undergone prior SI joint
steroid injections and 16.5 % had had prior radiofrequency
ablation of the sacral nerve root lateral branches. 37
(35.9 %) had undergone prior lumbar fusion.
Patient flow
To date, two subjects exited the study after receiving
treatment but prior to completion, both in the CM group, 1
due to inability to tolerate physical therapy (Fig. 2). The
six-month follow-up rate was 49/51 (96 %) in the CM
group and 52/52 (100 %) in the SIJF group. No subject
assigned to CM crossed over early. All subjects assigned to
SIJF underwent the procedure.
SIJ fusion
All subjects assigned to SIJF underwent the procedure soon
after assignment (median days to surgery: 18). 18 SIJF sub-
jects were diagnosed at baseline with bilateral SIJ pain
meeting study eligibility criteria; however, only 7 (39 %)
underwent bilateral SIJF, the remaining 11 patients receiving
only unilateral treatment. Mean procedure time was 57 min
(range 19–107 min). Fluoroscopy time, which was not col-
lected routinely at one center, averaged 2.3 min (range
1–4 min). In one case, four implants were placed; in the
remaining cases, three implants were placed. Median hospital
length of stay was 3 days (range 1–28). The long length of stay
was due to acute postoperative glaucoma causing severe
diminution of vision and requiring two eye surgeries.
Conservative management
For subjects assigned to CM, the mean number of PT
sessions was 26.5 and 37 (72.5 %) underwent at least 15
sessions of PT (Table 3). One subject withdrew due to
inability to tolerate PT.
Primary endpoint
At baseline mean VAS LBP was slightly higher in the SIJF
group vs the CM group (77.7 vs 73.0, p=0.0606). In the
CM group, mean LBP VAS decreased to 67.8 at 6 months
[mean (SD) improvement of 5.7 (24.4) points,
p=0.1105]. In the SIJF group, LBP VAS decreased to
34.4 [mean improvement of 43.3 (25.0) points, p\0.0001,
Fig. 3]. The difference in VAS LBP improvement was 37.6
points higher in the SIJF group; controlling for underlying
condition, the difference was 38.1 points (both
p\0.0001). A random effects model (with study site as a
random effect) showed a similar difference in pain
improvement across groups (37.8 points). By month 6,
78.8 % of subjects in the SIJF group had an improvement
in LBP VAS by at least 20 points (minimal clinically
important difference) compared to only 22.4 % in the CM
group (Fisher p\0.0001 for comparison). Preplanned
subgroup analysis for the primary endpoint, which included
pain related to pregnancy or not, history of prior lumbar
fusion or not and unilateral vs bilateral SIJ pain at baseline,
showed similar responses in subgroups. Additional sub-
group analysis, including gender, sex, age (by quartiles),
BMI category, pain duration (by quartiles), and whether
taking strong opioids at baseline, also showed no differ-
ences in responses between SIJF and CM within subgroups.
However, subjects who underwent bilateral SIJF had
smaller improvements in back pain compared to those who
underwent unilateral SIJF (analysis of variance
p=0.0110). Combining all postoperative time points,
back pain improved by 37.8 points more in the SIJF (re-
peated measures analysis of variance, p\0.0001).
Disability
Disability, as measured by Oswestry Disability Index (ODI)
score, was high at baseline (mean 56.6). In the CM group,
ODI improved slightly from baseline (mean improvement
5.8 points, p=0.0114, Fig. 3c). In the SIJF group, ODI
improved by 25.5 points (p\0.0001). The difference in
6 month ODI improvement across groups was 19.8 points,
p\0.0001, Fig. 3. All individual components of ODI
showed more improvements in the SIJF group vs CM group
(maximum pvalue 0.0002). The proportion of subjects with
a 15-point 6-month improvement in ODI from baseline was
71.2 vs 24.5 % (p\0.0001). Subgroup analysis showed no
factor that predicted change in ODI except that changes
were larger for subjects who underwent unilateral SIJF
(p=0.0134). Self-reported walking distance was signifi-
cantly increased after SIJF (Fig. 4a) but only minimally after
CM (proportional odds logistic regression, p=0.0111).
SIJ functionality
SIJ functionality was also assessed using the ASLR. Mean
(median) ASLR ratings decreased, expressed on the 0–6
scale, improved from 4.0 (4) to 2.0 (2) in the SIJF group
and from 3.8 (4) to 3.7 (4) in the CM group. Mean
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reductions were 2.0 points in the SIJF group and 0.2 points
in the CM group (p\0.0001). The proportion of subjects
who could raise the affected leg with no or minimal diffi-
culty at 6 months was 71.1 % in the SIJF group and 32.0 %
in the CM group (p=0.0002).
Quality of life
Mean (SD) EQ-5D TTO index and visual analog scale
(EQ-5D VAS) were markedly depressed in both groups at
baseline compared to age- and sex-matched population
norms (Fig. 4e, f). EQ-5D TTO improved more in the SIJF
group compared to the CM group [change of 0.37 points
(p\0.0001) in SIJF group change of 0.11 points in CM
group (p=0.0189), 0.21 point difference, p\0.0001].
Similarly, EQ-5D VAS improved more in the SIJF group
(20.2 points more improvement, p\0.0001).
Additional effectiveness outcomes
Satisfaction levels were higher at months 3 and 6 in the SIJF
group compared to the CM group (Table 4, Fig. 4c,
p\0.0001 by proportional odds logistic regression) as were
the proportion of patients reporting that they would have the
assigned intervention again (Fig. 4d, p=0.0001). A larger
proportion of SIJF subjects reported they were improved
Table 1 Baseline
characteristics of enrolled/
randomized subjects
CM
(n=51)
SIJ Fusion
(n=52)
pvalue**
Age, mean (SD) [range] 46.7 [23–69] 49.4 [27–70] 0.2104
Female, N(%) 37 (72.5) 38 (73.1) 1.0000
Pain duration, mean (SD) [range] 4.5 [0.45–23] 4.9 [0.58–44] 0.7765
Body mass index, mean (SD) [range] 27.6 [16–44] 26.5 [18–42] 0.3545
Smoking, N(%)
Current 16 (31.4) 23 (44.2) 0.0444
Former 8 (15.7) 14 (26.9)
Never 27 (52.9) 15 (28.8)
Pain syndrome
Pain began in peripartum period 3 (5.9 %) 6 (11.5 %) 0.4878
Radiates down leg 40 (78.4 %) 42 (80.8 %) 0.8107
Pain in groin 36 (70.6 %) 31 (59.6 %) 0.3027
Pain sitting 38 (74.5 %) 42 (80.8 %) 0.4856
Pain rising 40 (78.4 %) 48 (92.3 %) 0.0546
Pain walking 42 (82.4 %) 43 (82.7 %) 1.0000
Pain climbing stairs 41 (80.4 %) 41 (78.8 %) 1.0000
Pain descending stairs 29 (56.9 %) 33 (63.5 %) 0.5491
Prior treatment
Prior physical therapy 27 (52.9 %) 32 (61.5 %) 0.4287
Prior prolotherapy 0 (0 %) 0 (0 %) 1.0000
Prior steroid SIJ injections 38 (74.5 %) 37 (71.2 %) 0.8253
Prior radiofrequency ablation
a
6 (11.8 %) 11 (21.2 %) 0.2888
Work status
Working normal hours/type 3 (5.9 %) 5 (9.6 %) 0.7918
Working with limitations 12 (23.5 %) 13 (25.0 %)
Not working due to lower back pain 27 (52.9 %) 23 (44.2 %)
Not working due to other reason 2 (3.9 %) 1 (1.9 %)
Retired 7 (13.7 %) 10 (19.2 %)
Ambulatory status
Ambulatory without assistance 46 (90.2 %) 42 (80.8 %) 0.2945
Ambulatory with assistance 3 (5.9 %) 8 (15.4 %)
Cannot walk 2 (3.9 %) 2 (3.8 %)
History of prior lumbar fusion 19 (37.3 %) 18 (34.6 %) 0.8388
** Fisher test for nominal variables; ttest for continuous variables
a
Radiofrequency ablation of lateral branches of sacral nerve root
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overall compared to baseline (Fig. 4d, p\0.0001). Self-re-
ported walking distance and global comparison to baseline
were also higher for the SIJF group (Fig. 4a and b).
Adverse events
Within 180 days of initial treatment, there were 24 repor-
ted adverse events: 10 events in 9 SIJF subjects and 14
events in 13 CM subjects. The mean (median) number of
events per subject prior to 180 days was slightly smaller in
the SIJF group compared to CM: 0.19 (0) vs 0.27 (0),
p=0.0918. There were 18 severe adverse events prior to
month 6, 8 in the SIJF group and 10 in the CM group.
Adverse event severity was distributed equally across
groups (Wilcoxon pvalue 0.7868). Of the 8 severe adverse
events in the SIJF group, none were related to the device
and 2 were related to the procedure (postoperative hema-
toma and postoperative neural impingement related to
incorrect device placement). The two procedure-related
severe adverse events in the SIJF group were both rever-
sible and within the spectrum of possible surgical com-
plications known from comparable spine procedures.
Device- and procedure-related events
One subject had postoperative radicular pain resulting from
implant protrusion into the sacral neural foramen. Pain
resolved when the implant was pulled back a few mm. Two
additional subjects had postoperative hematomas; one
resulted in gluteal pain and required surgical evacuation
and one was treated conservatively. No subject has
undergone late revision of implants.
Discussion
In our trial of patients with chronic SIJ pain, improvements
in LBP, disability scores, physical function and quality of
life were superior in subjects receiving minimally invasive
SIJF using triangular titanium implants compared to CM.
Differences in these outcomes occurred soon after treat-
ment initiation and were statistically significant between
the two groups at all postoperative time points.
Our findings both replicate and extend previous studies.
In previously published case series [36–39], systematic
reviews [40,41], a prospective multicenter clinical trial
[42], and a recently published randomized clinical trial of
similar design conducted in the USA [43], similar
improvements in SIJ pain, self-rated limitations in activi-
ties due to pain (Oswestry Disability Index) and quality of
life were observed in participants undergoing SIJF. Our
study provides an additional, independent confirmation that
the improvements after surgery are clinically important and
statistically superior to those seen with continued
Fig. 2 Patient flow
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conservative care. Similar to previous studies, preplanned
subgroup analyses revealed no predictors of poor responses
after surgical fusion.
Our randomized trial differed in design and intervention
compared to a US randomized trial; in the US study, non-
surgical management included intraarticular SIJ steroid
injections and radiofrequency (RF) ablation. Instead, our
trial included only PT and adequate information and reas-
surance, consistent with European guidelines for pelvic
girdle pain [29]. We note that although SIJ steroid injec-
tions and RF ablation are not commonly delivered in
Europe, many trial participants had already undergone such
treatments.
Subjects in our cohort had marked reduction in base-
line quality of life compared to the general population,
with EQ-5D scores substantially lower than population
controls. At 3 and 6 months, minimally invasive SIJF
resulted in improved EQ-5D scores (postoperative means
Fig. 3 Improvement in VAS low back pain (a) and change from
baseline (b), Oswestry Disability Index (c), active straight leg raise
test (d), EQ-5D time trade-off (TTO) index (e), and EQ-5D visual
analog scale. For all plots, green lines show SIJF and blue lines show
CM. For eand f,green and blue horizontal lines indicate age- and
sex-matched German population norms and arrows represent baseline
(bottom of arrow) and 12-month findings (top of arrow) from the most
recent Swedish Spine Registry data [34]
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of 0.69 and 0.74) that were similar to postoperative values
observed for other low back pain surgical procedures [44].
In contrast, EQ-5D score improvements in the CM group
were minimal. The improvements in quality of life seen
in our study mirror those seen in a prior randomized trial
[43]. Our study, combined with the prior randomized trial
and 4- and 5-year outcomes from both European [39] and
US [45] cohorts, suggest that minimally invasive SIJ
fusion can be added to the portfolio of spine surgeries
proven safe and effective that European surgeons can
offer their patients.
Minimal clinically important differences (MCID) are
often used to assess the clinical significance of study
findings as they may be distinct from statistical differences.
Although they were developed for degenerative spinal
conditions other than SIJ and the effects of SIJF, the MCID
for improvement in chronic back pain is approximately
20 % when measured by VAS [46] and that for ODI is
approximately 13–15 points [47]. For EQ-5D, the MCID is
less well defined, with changes of 0.15–0.46 reported [44,
48]. Observed mean values in our study exceeded these
MCID values for pain, ODI and EQ-5D, and response rates
were markedly higher in the SIJF group compared to CM.
Improvements in EQ-5D TTO and VAS in our study were
similar to those seen in the Swedish spine registry for other
spine surgeries [34].
Our results extend findings from prior studies in
important ways. First, we included two functional assess-
ments [walking distance and physical functioning
(ASLR)], both of which have not been previously reported.
Both measures showed improvement in the SIJF group but
not in the CM group. Second, CM was provided per
European treatment guidelines, meaning that the control
group intervention may have been more standardized than
prior trials. Our findings extend prior trials and serve to
validate the procedure overall.
Surgical revision is an important clinical outcome. To
date, only one trial subject has undergone revision surgery
after SIJF; in this case, the implant was placed too close to
Fig. 4 Improvement in self-reported walking distance (a), global comparison to baseline (b), satisfaction level (c), and desirability of having
surgery again (d) in subjects treated with SIJF or CM
Table 2 Characteristics of SIJ fusion
SIJF
(n=52)
Days from enrollment to surgery, median (range) 18 (1–82)
Number of implants, N(%)
Three 51 (98.1%)
Four 1 (1.9%)
Procedure duration (min), median (range) 54 (19–107)
Fluoroscopy time (min), median (range)
a
2.1 (1.0–4.0)
Hospital length of stay (days), median (range) 3 (1–28)
a
Some sites did not record fluoroscopy time
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the sacral nerve root, a known risk, and this subject’s new
radicular pain improved on repositioning the implant. The
risk of early revision of this implant is approximately 1 %
and the risk of revision at 4 years is approximately 3.6 %
[49], a revision rate that is low compared to standard open
surgical procedures in the spine [50,51]. No unanticipated
adverse events occurred.
Our study has several limitations. Because the inter-
vention was not blinded, we cannot rule out the possibility
that knowledge of the treatment assignment might have
influenced patient responses to questions, which could have
contributed to the greater improvements seen in the SIJF
group. However, other potential biases—e.g., the fact that
11 of the 18 patients in the SIJF group diagnosed with
bilateral pain received only unilateral SIJF, might have
decreased the improvements in the SIJF group due to under
treatment. Moreover, blinding is not done in standard
clinical settings, so our results may be more generalizable
Table 3 Characteristics of CM
CM
(n=51)
Physical therapy sessions, N(%)
1 1 (2.0)
2–5 2 (3.9)
6–10 1 (2.0)
11–15 9 (17.6)
[15 37 (72.5)
Cognitive behavioral therapy sessions, N(%)
0 27 (52.9)
1 1 (2.0)
2–5 7 (13.7)
6–10 10 (19.6)
11–15 3 (5.9)
[15 3 (5.9)
Table 4 Other outcomes at
6 months CM SIJF pvalue
Walking distance
\100 m 12 (24.5 %) 6 (11.8 %) 0.0111
100–500 m 17 (34.7 %) 12 (23.5 %)
0.5–1 km 10 (20.4 %) 13 (25.5 %)
[1 km 10 (20.4 %) 20 (39.2 %)
Work status
Not working due to lower back pain 28 (57.1 %) 20 (39.2 %) 0.0711
Not working due to other reason 0 (0.0 %) 2 (3.9 %)
Retired 5 (10.2 %) 11 (21.6 %)
Working with limitations 10 (20.4 %) 6 (11.8 %)
Working normal hours/type 6 (12.2 %) 12 (23.5 %)
Walking status
Ambulatory without assistance 45 (91.8 %) 46 (90.2 %) 1.0000
Ambulatory with assistance 2 (4.1 %) 5 (9.8 %)
Cannot walk 2 (4.1 %) 0 (0.0 %)
Level of satisfaction
Very satisfied 9 (18.4 %) 28 (54.9 %) \0.0001
Somewhat satisfied 15 (30.6 %) 19 (37.3 %)
Somewhat dissatisfied 23 (46.9 %) 2 (3.9 %)
Very dissatisfied 2 (4.1 %) 2 (3.9 %)
Desirability of having assigned treatment again
Definitely not 10 (20.4 %) 2 (3.9 %) 0.0001
Don’t know 18 (36.7 %) 8 (15.7 %)
Definitely yes 21 (42.9 %) 41 (80.4 %)
Global comparison to baseline
Worse 16 (32.7 %) 3 (5.9 %) \0.0001
Same 17 (34.7 %) 6 (11.8 %)
Better 12 (24.5 %) 22 (43.1 %)
Much better 4 (8.2 %) 20 (39.2 %)
716 Eur Spine J (2017) 26:708–719
123
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
to what can be expected in standard practice compared to a
blinded trial.
While we included patients for whom the SIJ had been
identified as the primary cause of LBP, we cannot exclude
that patients with other contributory sources of LBP, e.g.,
facet arthropathy or degenerative disc disease, have been
enrolled. In these patients the LBP due to the SIJ pathology
might have been reduced; however, the other causes of the
LBP might not have been addressed adequately. It is rea-
sonable to suppose that both arms of the study are equally
affected by this potential problem.
Second, although CM was patterned after European
guidelines for pelvic girdle pain, which recommend treat-
ment individualized to patient needs, non-surgical care
provided to patients in our trial may have varied across
centers. Physical therapy may be helpful in post-partum
pelvic girdle pain [45], most of which is likely to emanate
from the SIJ, but the target population in our study differs
from the cited study. Finally, our report includes 6-month
data only; the study continues to 24 months of planned
follow-up. However, one-year data from other prospective
trials of the same device/patient population [42,43], as
well as longer-term data from retrospective cohorts [39,45]
suggest sustained effectiveness.
In summary, 6-month data from a randomized surgery
vs non-surgical clinical trial show that minimally invasive
SIJF using triangular titanium implants provided superior
pain, disability, function and quality of life outcomes
compared to CM (Figs. 3,4, Table 4). Combined with
previous evidence, minimally invasive SIJF is a reasonable
surgical option for patients with SIJ pain not responsive to
non-surgical care for at least 6 months.
Acknowledgments The authors would like to thank Peter Vajkoczy
(Department of Neurosurgery, Charite
´- Berlin, Germany) for co-
authoring a presentation of preliminary data of iMIA at both the
annual meeting of the German Society of Neurosurgery/Spine Sec-
tion in Berlin in October 2015 and at the annual meeting of the
German Spine Society in Frankfurt in December 2015. The authors
acknowledge Daniel Cher (SI-BONE, Inc., San Jose, California,
USA) and Eddie Van Eeckhoven (Eeckhoven bvba, Kontich, Bel-
gium) for help with iMIA design, oversight, data analysis and
preparation of a draft manuscript. The authors also gratefully
acknowledge study sponsorship and monitoring/source verification by
SI-BONE staff and contractors. Finally, the authors thank the patients
who participated in the iMIA trial.
Compliance with ethical standards
Conflict of interest Bengt Sturesson, Julius Dengler, Djaya Kools,
Robert Pflugmacher, Domenico Prestamburgo and Alessandro Gas-
barrini are investigators in SI-BONE clinical trials. Bengt Sturesson,
Djaya Kools and Robert Pflugmacher are paid consultants to SI-
BONE. The trial reported herein was funded by SI-BONE.
Open Access This article is distributed under the terms of the
Creative Commons Attribution 4.0 International License (http://
creativecommons.org/licenses/by/4.0/), which permits unrestricted
use, distribution, and reproduction in any medium, provided you give
appropriate credit to the original author(s) and the source, provide a
link to the Creative Commons license, and indicate if changes were
made.
Appendix
iMIA Study Investigators/study coordinators
Aalst, Belgium - D. Kools, G. Lesage, F. Martens, H.
Keymeulen.
Montegne´e, Belgium - Y. Lecomte.
Berlin, Germany - J. Dengler, S. Bayerl, J. Kopetzki.
Bonn, Germany - R. Pflugmacher, M. Webler, R.
Bornemann, T. Jansen.
Hilden, Germany - A. Mues.
Bologna, Italy - A. Gasbarrini, C. Griffoni, S. Colangeli,
R. Ghermandi.
Legnano, Italy - D. Prestamburgo, F. Valli.
Pavia, Italy - P. Gaetani, V. Silvani, M. Minelli, D.
Adinolfi, M. Verlotta, A. Cattalani.
A
¨ngelholm, Sweden - B. Sturesson, I. Dahlberg.
References
1. Erichsen J (1859) A lecture on the sacro-iliac disease. Lancet
73:25–27. doi:10.1016/S0140-6736(02)20467-5
2. Goldthwait JE, Osgood RB (1905) A consideration of the pelvic
articulations from an anatomical, pathological and clinical
standpoint. Boston Med Surg J 152:593–601
3. Steindler A (1938) Differential diagnosis of pain low in the back.
JAMA 110:106–113
4. Mixter W, Barr J (1934) Rupture of the intervertebral disc with
involvement of the spinal canal. N Engl J Med 211:210–215
5. Sembrano JN, Polly DW (2009) How often is low back pain not
coming from the back? Spine 34:E27–E32. doi:10.1097/BRS.
0b013e31818b8882
6. Bernard TN, Kirkaldy-Willis WH (1987) Recognizing specific
characteristics of nonspecific low back pain. Clin Orthop
217:266–280
7. DePalma MJ, Ketchum JM, Saullo TR (2011) Etiology of chronic
low back pain in patients having undergone lumbar fusion. Pain
Med 12:732–739. doi:10.1111/j.1526-4637.2011.01098.x
8. Liliang P-C, Lu K, Liang C-L et al (2011) Sacroiliac joint pain
after lumbar and lumbosacral fusion: findings using dual
sacroiliac joint blocks. Pain Med Malden Mass 12:565–570.
doi:10.1111/j.1526-4637.2011.01087.x
9. Schofield DJ, Callander EJ, Shrestha RN et al (2015) Back prob-
lems, comorbidities, and their association with wealth. Spine J Off
J North Am Spine Soc 15:34–41. doi:10.1016/j.spinee.2014.06.018
10. Sturesson B (2007) CHAPTER 23—Movement of the sacroiliac
joint with special reference to the effect of load A2—Wilson,
Andry VleemingVert MooneyRob StoeckartPhilip. In: Mov.
Stab. Lumbopelvic Pain Second Ed. Churchill Livingstone,
Edinburgh, pp 343–352
11. Vleeming A, Volkers AC, Snijders CJ, Stoeckart R (1990)
Relation between form and function in the sacroiliac joint. Part II:
biomechanical aspects. Spine 15:133–136
Eur Spine J (2017) 26:708–719 717
123
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
12. Sturesson B, Selvik G, Ude
´n A (1989) Movements of the
sacroiliac joints. A roentgen stereophotogrammetric analysis.
Spine 14:162–165
13. Gaenslen FJ (1927) Sacro-iliac arthrodesis: indications, author’s
technic and end-results. J Am Med Assoc 89:2031–2035
14. Smith-Petersen MN (1921) Arthrodesis of the sacroiliac joint. A
new method of approach. J Bone Jt Surg 3:400–405
15. Hagen R (1974) Pelvic girdle relaxation from an orthopaedic
point of view. Acta Orthop Scand 45:550–563
16. Waisbrod H, Krainick JU, Gerbershagen HU (1987) Sacroiliac
joint arthrodesis for chronic lower back pain. Arch Orthop
Trauma Surg Arch Fu
¨r Orthop Unf-Chir 106:238–240
17. Kibsga
˚rd TJ, Røise O, Sudmann E, Stuge B (2013) Pelvic joint
fusions in patients with chronic pelvic girdle pain: a 23-year fol-
low-up. Eur Spine J 22:871–877. doi:10.1007/s00586-012-2512-8
18. Giannikas KA, Khan AM, Karski MT, Maxwell HA (2004)
Sacroiliac joint fusion for chronic pain: a simple technique
avoiding the use of metalwork. Eur Spine J Off Publ Eur Spine
Soc Eur Spinal Deform Soc Eur Sect Cerv Spine Res Soc
13:253–256. doi:10.1007/s00586-003-0620-1
19. Buchowski JM, Kebaish KM, Sinkov V et al (2005) Functional
and radiographic outcome of sacroiliac arthrodesis for the
disorders of the sacroiliac joint. Spine J Off J North Am Spine
Soc 5:520–528. doi:10.1016/j.spinee.2005.02.022 (discussion
529)
20. Schu
¨tz U, Grob D (2006) Poor outcome following bilateral
sacroiliac joint fusion for degenerative sacroiliac joint syndrome.
Acta Orthop Belg 72:296–308
21. Belanger TA, Dall BE (2001) Sacroiliac arthrodesis using a
posterior midline fascial splitting approach and pedicle screw
instrumentation: a new technique. J Spinal Disord 14:118–124
22. Manfre
´L (2014) Percutaneous sacroiliac joint fixation in
sacroiliac instability. The first case report using a fully CT-guided
technique. Interv Neuroradiol J Peritherapeutic Neuroradiol Surg
Proced Relat Neurosci 20:621–625
23. Ledonio CGT, Polly DW, Swiontkowski MF (2014) Minimally
invasive versus open sacroiliac joint fusion: are they similarly
safe and effective? Clin Orthop 472:1831–1838. doi:10.1007/
s11999-014-3499-8
24. Ledonio C, Polly D, Swiontkowski MF, Cummings J (2014)
Comparative effectiveness of open versus minimally invasive
sacroiliac joint fusion. Med Devices Evid Res 2014:187–193.
doi:10.2147/MDER.S60370
25. Graham Smith A, Capobianco R, Cher D et al (2013) Open versus
minimally invasive sacroiliac joint fusion: a multi-center com-
parison of perioperative measures and clinical outcomes. Ann
Surg Innov Res 7:14. doi:10.1186/1750-1164-7-14
26. Fortin JD, Falco FJ (1997) The Fortin finger test: an indicator of
sacroiliac pain. Am J Orthop Belle Mead NJ 26:477–480
27. Szadek KM, van der Wurff P, van Tulder MW et al (2009)
Diagnostic validity of criteria for sacroiliac joint pain: a sys-
tematic review. J Pain 10:354–368. doi:10.1016/j.jpain.2008.09.
014
28. Fairbank JC, Pynsent PB (2000) The Oswestry disability index.
Spine 25:2940–2952 (discussion 2952)
29. Vleeming A, Albert HB, O
¨stgaard HC et al (2008) European
guidelines for the diagnosis and treatment of pelvic girdle pain.
Eur Spine J 17:794–819. doi:10.1007/s00586-008-0602-4
30. Rudolf L (2012) Sacroiliac joint arthrodesis-mis technique
with titanium implants: report of the first 50 patients and
outcomes. Open Orthop J 6:495–502. doi:10.2174/
1874325001206010495
31. Mens JM, Vleeming A, Snijders CJ et al (2001) Reliability and
validity of the active straight leg raise test in posterior pelvic pain
since pregnancy. Spine 26:1167–1171
32. EuroQol Group (1990) EuroQol–a new facility for the measure-
ment of health-related quality of life. Health Policy Amst Neth
16:199–208
33. Ko
¨nig H-H, Bernert S, Angermeyer MC et al (2009) Comparison
of population health status in six european countries: results of a
representative survey using the EQ-5D questionnaire. Med Care
47:255–261. doi:10.1097/MLR.0b013e318184759e
34. Stro
¨mqvist B, Fritzell P, Ha
¨gg O et al (2013) Swespine: the
Swedish spine register. Eur Spine J 22:953–974. doi:10.1007/
s00586-013-2758-9
35. Core Team R (2013) R: a language and environment for statis-
tical computing. Austria, Vienna
36. Cummings J Jr, Capobianco RA (2013) Minimally invasive
sacroiliac joint fusion: one-year outcomes in 18 patients. Ann
Surg Innov Res 7:12. doi:10.1186/1750-1164-7-12
37. Sachs D (2013) Minimally Invasive versus Open Sacroiliac Joint
Fusion: A Comparison of Process Measures and Description of
Technique. In: Int. Soc. Adv. Spine Surg. Vancouver, p 187
38. Gaetani P, Miotti D, Risso A et al (2013) Percutaneous
arthrodesis of sacro-iliac joint: a pilot study. J Neurosurg Sci
57:297–301
39. Vanaclocha VV, Verdu
´-Lo
´pez F, Sa
´nchez-Pardo M et al (2014)
Minimally invasive sacroiliac joint arthrodesis: experience in a
prospective series with 24 patients. J Spine. doi:10.4172/2165-
7939.1000185
40. Heiney J, Capobianco R, Cher D (2015) Systematic review of
minimally invasive sacroiliac joint fusion using a lateral
transarticular approach. Int J Spine Surg. doi:10.14444/2040
41. Lingutla KK, Pollock R, Ahuja S (2016) Sacroiliac joint fusion
for low back pain: a systematic review and meta-analysis. Eur
Spine J. doi:10.1007/s00586-016-4490-8
42. Duhon BS, Cher DJ, Wine KD et al (2015) Triangular titanium
implants for minimally invasive sacroiliac joint fusion: a
prospective study. Glob Spine J 6:257–269. doi:10.1055/s-0035-
1562912
43. Polly DW, Cher DJ, Wine KD et al (2015) Randomized con-
trolled trial of minimally invasive sacroiliac joint fusion using
triangular titanium implants vs nonsurgical management for
sacroiliac joint dysfunction: 12-month outcomes. Neurosurgery
77:674–691. doi:10.1227/NEU.0000000000000988
44. Parker SL, Adogwa O, Mendenhall SK et al (2012) Determina-
tion of minimum clinically important difference (MCID) in pain,
disability, and quality of life after revision fusion for symp-
tomatic pseudoarthrosis. Spine J 12:1122–1128. doi:10.1016/j.
spinee.2012.10.006
45. Rudolf L, Capobianco R (2014) Five-year clinical and radio-
graphic outcomes after minimally invasive sacroiliac joint fusion
using triangular implants. Open Orthop J 8:375–383. doi:10.
2174/1874325001408010375
46. Haefeli M, Elfering A (2006) Pain assessment. Eur Spine J Off
Publ Eur Spine Soc Eur Spinal Deform Soc Eur Sect Cerv Spine
Res Soc 15(Suppl 1):S17–S24. doi:10.1007/s00586-005-1044-x
47. Copay AG, Cher DJ (2015) Is the Oswestry Disability Index a
valid measure of response to sacroiliac joint treatment? Qual Life
Res Int J Qual Life Asp Treat Care Rehabil. doi:10.1007/s11136-
015-1095-3
48. Parker SL, Adogwa O, Paul AR et al (2011) Utility of minimum
clinically important difference in assessing pain, disability, and
health state after transforaminal lumbar interbody fusion for
degenerative lumbar spondylolisthesis. J Neurosurg Spine
14:598–604. doi:10.3171/2010.12.SPINE10472
49. Cher DJ, Reckling WC, Capobianco RA (2015) Implant sur-
vivorship analysis after minimally invasive sacroiliac joint fusion
using the iFuse Implant System. Med Devices Evid Res
8:485–492. doi:10.2147/MDER.S94885
718 Eur Spine J (2017) 26:708–719
123
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
50. Martin BI, Mirza SK, Comstock BA et al (2007) Reoperation
rates following lumbar spine surgery and the influence of spinal
fusion procedures. Spine 32:382–387. doi:10.1097/01.brs.
0000254104.55716.46
51. Martin BI, Mirza SK, Flum DR et al (2012) Repeat surgery after
lumbar decompression for herniated disc: the quality implications
of hospital and surgeon variation. Spine J Off J North Am Spine
Soc 12:89–97. doi:10.1016/j.spinee.2011.11.010
Eur Spine J (2017) 26:708–719 719
123
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
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