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Six-month outcomes from a randomized controlled trial of minimally invasive SI joint fusion with triangular titanium implants vs conservative management


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Purpose: To compare the safety and effectiveness of minimally invasive sacroiliac joint fusion (SIJF) using triangular 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 consisted of optimization of medical therapy, individualized physical therapy (PT) and adequate information and reassurance 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 included 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 (difference 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.
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Six-month outcomes from a randomized controlled trial
of minimally invasive SI joint fusion with triangular titanium
implants vs conservative management
Bengt Sturesson
Djaya Kools
Robert Pflugmacher
Alessandro Gasbarrini
Domenico Prestamburgo
Julius Dengler
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
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.
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
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
Department of Orthopedics, Aleris, A
¨ngelholm Hospital,
¨ngelholm, Sweden
Department of Neurosurgery, Onze-Lieve-Vrouw Hospital
Aalst, Aalst, Belgium
Department of Orthopedics and Traumatology, University
Hospital Bonn, Bonn, Germany
Instituto Ortopedico Rizzoli di Bologna, Bologna, Italy
Department of Orthopedics and Traumatology, ASST Ovest
Milanese, Ospedale di Legnano, Legnano, Italy
Department of Neurosurgery, Charite
´, Universitaetsmedizin
Berlin, Berlin, Germany
Eur Spine J (2017) 26:708–719
DOI 10.1007/s00586-016-4599-9
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
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 [1012] 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
[1519]. 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 [2325]. 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.
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
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
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
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
(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
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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].
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, 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
SIJ Fusion
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
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
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.
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 [3639], 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
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
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)
2.1 (1.0–4.0)
Hospital length of stay (days), median (range) 3 (1–28)
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
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
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://, 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
iMIA Study Investigators/study coordinators
Aalst, Belgium - D. Kools, G. Lesage, F. Martens, H.
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.
¨ngelholm, Sweden - B. Sturesson, I. Dahlberg.
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... 20 Health state utility values (derived from EQ-5D TTO) were informed by three prospective, multicenter, clinical trials (INSITE, SIFI, iMIA), where "success" was defined as a decrease in Visual Analog Scale (VAS) of at least 20 points. [21][22][23][24] The health state utility values for mild and severe SIJ pain were 0.77 and 0.45, respectively, where 1.0 reflects full health and 0 reflects death. [21][22][23][24] The health-state utility value of 0.45 for severe pain captures the utility decrement associated with an unsuccessful response, including complications and subsequent procedures. ...
... [21][22][23][24] The health state utility values for mild and severe SIJ pain were 0.77 and 0.45, respectively, where 1.0 reflects full health and 0 reflects death. [21][22][23][24] The health-state utility value of 0.45 for severe pain captures the utility decrement associated with an unsuccessful response, including complications and subsequent procedures. [21][22][23][24] Among patients with MLF who did not undergo pelvic fixation, Finger et al reported the onset of post-operative SIJ pain in 29.4% of patients at 12-month follow-up; similarly, Unoki et al reported a post-operative incidence of SIJ pain of 32.1%, where the mean time to onset of SIJ pain was approximately 4 months (range, 1-10 months). ...
... [21][22][23][24] The health-state utility value of 0.45 for severe pain captures the utility decrement associated with an unsuccessful response, including complications and subsequent procedures. [21][22][23][24] Among patients with MLF who did not undergo pelvic fixation, Finger et al reported the onset of post-operative SIJ pain in 29.4% of patients at 12-month follow-up; similarly, Unoki et al reported a post-operative incidence of SIJ pain of 32.1%, where the mean time to onset of SIJ pain was approximately 4 months (range, 1-10 months). 4,5 Based on two randomized clinical trials of minimally invasive SIJF using triangular titanium implants, among patients with a history of lumbar fusion, Polly et al and Dengler et al reported relative risk reductions (RRR) in post-operative SIJ pain of 82% and 73%, respectively, at 6-month follow-up. ...
Full-text available
Purpose: Multi-level lumbar fusion to the sacrum (MLF) can lead to increased stress and angular motion across the sacroiliac joint (SIJ), with an incidence of post-operative SIJ pain estimated at 26-32%. SIJ fusion (SIJF) can help obviate the need for revisions by reducing range of motion and screw stresses. We aimed to evaluate the cost-utility of MLF + SIJF compared to MLF alone among high-risk patients from a payer perspective, where high risk is defined as high body mass index and high pelvic incidence. Methods: A Markov process decision-analysis model was developed to evaluate cumulative 5-year costs, quality-adjusted life years (QALYs), and incremental cost-effectiveness ratio (ICER) of MLF + SIJF compared to MLF alone using published data; costs from Medicare claims data analyses and health state utility values (derived from EQ-5D) informed by three prospective, multicenter, clinical trials. The base case assumed a reduction in post-operative SIJ pain from 30% to 10% (relative risk reduction [RRR] of 67%). Costs and utilities were discounted 3% annually. The ICER is reported in 2020 US dollars. One-way, multi-way, and probabilistic sensitivity analyses were performed. Results: With an assumed 30% incidence of SIJ pain after MLF alone, stabilizing with SIJF was associated with an additional 5-year cost of $2421 and a gain of 0.14 QALYs, resulting in an ICER of $17,293 per QALY gained (similar to total knee arthroplasty and more favorable than open discectomy). ICERs were most sensitive to the RRR of post-operative SIJ pain conferred by SIJF, time horizon, and probability of successful treatment with MLF alone. At a willingness-to-pay threshold of $50,000/QALY gained, MLF + SIJF has a 97.7% probability of being cost-effective in the target patient population. Conclusion: Fusing the SIJ in high-risk patients undergoing MLF was cost-effective when the incidence of post-operative SIJ pain after MLF alone exceeds approximately 25%, providing value-based healthcare from a payer perspective.
... Here, we present the first multicenter, single arm, prospective data set, at a planned analysis at 6 months for sacroiliitis treatment utilizing a novel posterior approach, single point, percutaneous machined allograft technique for SIJ fixation. We have chosen to present the first 69 patients consecutively enrolled and implanted in the study, as the precedent to present approximately 50 patients that were followed prospectively following a lateral fusion approach has already been established and published [20]. ...
... Principle investigators at each study site were responsible for the diagnosis of sacroiliitis as well as ensuring patients are eligible for the study based on the inclusion and exclusion criteria. Of note, inclusion and exclusion criteria was similar to previously published prospective studies on minimally invasive sacroiliac fusion [20,21]. ...
... This data represents the first report on any posterior approach for the treatment of sacroiliac joint dysfunction in a prospective multicenter fashion, with an enrollment of > 100 patients. We are reporting on the 6-month interim analysis for nearly 70 patients, as this has been performed for the treatment arm for historical approaches for sacroiliac joint fusion in a prospective manner [20,22], with planned followup of the complete cohort at 6, 12, 18 and 24 months [21,[23][24][25]. This represents the first prospective data for posterior sacroiliac joint fusion. ...
Full-text available
Introduction: Sacroiliac joint disease is a prominent diagnosis across the world. A novel fixation technique employing a posterior approach, single point, bone allograft tranfixation has proven to be helpful anecdotally. The purpose of this is study is to investigate prospectively the safety and efficacy of this approach. Methods: A multicenter, prospective, single arm study was performed after patient identification and treatment with the novel posterior fusion, single-point transfixation system and followed for 24 months. Target enrollment is 100 patients. Interim results on the first 69 consecutive patients at 6 months is presented. Primary endpoint at 6-month analysis was Pain Intensity reduction by visual analogue scale and functional improvement by Oswestry Disability Index. Adverse events were assessed for safety analysis. Results: : 69 patients were identified for this analysis. At 6 months, a mean improvement of 34.9 was identified by a reduction in VAS and functional improvement was demonstrated by a mean reduction in ODI of 17.7. There were three adverse events, all unrelated to the device. Conclusion: The posterior single point transfixation is safe and efficacious for the treatment of sacroiliac joint dysfunction with statistical improvements in pain and function.
... Further, in both trials a larger proportion of patients allocated to fusion were able to achieve at least a 20-mm decrease in VAS pain scores compared to patients allocated to conservative management (Appendix 6 of the online supplement). iMIA authors reported no differences in effects of fusion compared to conservative management among subgroups defined by prior lumbar fusion, bilateral pain, or pregnancy-related pain at 6 months [38]. INSITE authors also reported no differences based on pain etiology (degenerative sacroiliitis vs. SI joint disruption), prior lumbar fusion, or bilateral procedure at 6 months [35]. ...
... Both INSITE and iMIA reported improvements in VAS pain scores beyond 6 months (outcomes rated high risk of bias due to extensive crossovers). In iMIA [38,39], authors continued to observe significantly larger improvements in pain at 1 year (-27.6 mm, p<.0001) and 2 years (-34 mm, p<.0001) for fusion compared to conservative management using the last observation carried forward (LOCF) method for imputing data for patients that crossed over [39,41]. The improvements in pain reported at 1 year was similar in INSITE [35,37], which reported findings separately for those who crossed over and those who did not. ...
... { For participants who crossed over from conservative management to surgery, the last observation carried forward method was used to impute their 1-year and 2-year follow-up data. [38]. However, INSITE [35] authors did not observe a significant difference in change in ODI scores between groups at 1 year. ...
Background context Sacroiliac (SI) joint pain causes significant disability and impairment to quality of life (QOL). Minimally invasive SI joint fusion is increasingly used to relieve chronic SI joint pain among patients who do not respond to non-surgical treatment. Purpose To systematically review the existing literature to assess the effectiveness and safety of minimally invasive SI joint fusion. Study design/setting Systematic review Data Sources PubMed, Embase, Cochrane, and a clinical trial registry from database inception to June 30, 2021. Study Selection Eligible studies were primary research studies published in the English language, enrolled adults with SI joint pain, and compared SI joint fusion to nonsurgical interventions or alternative minimally invasive procedures. We included randomized controlled trials (RCTs) or controlled cohort studies (CCSs) that reported effectiveness (pain, physical function, QOL, opioid use) or safety outcomes (adverse events (AEs), revision surgeries) and uncontrolled studies that reported safety outcomes. Data Abstraction and Synthesis Data were abstracted into structured forms; two independent reviewers assessed risk of bias using standard instruments; certainty of evidence was rated using GRADE. Results Forty studies (2 RCTs, 3 CCSs, and 35 uncontrolled studies) were included. Minimally invasive SI joint fusion with the iFuse Implant System appeared to result in larger improvements in pain (2 RCTs: mean difference in visual analog scale -40.5 mm, 95% CI, -50.1 to -30.9; -38.1 mm, P<0.0001) and larger improvements in physical function (mean difference in Oswestry Disability Index -25.4 points, 95% CI, -32.5 to -18.3; -19.8 points, P<0.0001) compared to conservative management at 6 months. Improvements in pain and physical function for the RCTs appeared durable at 1- and 2-year follow-up. Findings were similar in 1 CCS. The two RCTs also found significant improvements in QOL at 6 months and 1 year. Opioid use may be improved at 6 months and 1 to 2 years. AEs appeared higher in the fusion group at 6 months. The incidence of revision surgery varied by study; the highest was 3.8% at 2 years. Two CCS compared the effectiveness of alternative minimally invasive fusion procedures. One CCS compared iFuse to the Rialto SI Fusion System and reported no differences in pain, function, QOL, and revision surgeries from 6 months to 1 year. One CCS compared iFuse to percutaneous screw fixation and reported significantly fewer revisions among iFuse participants (mean difference -61.0%, 95% CI, -78.4% to -43.5%). The 35 uncontrolled studies had serious limitations and reported heterogeneous safety outcomes. Two of the larger studies reported a 13.2% incidence of complications from minimally invasive SI joint fusion at 90 days using an insurance claims database and a 3.1% incidence of revision surgery over 2.5 years using a post-market surveillance database. Conclusions Among patients meeting diagnostic criteria for SI joint pain and who have not responded to conservative care, minimally invasive SI joint fusion is probably more effective than conservative management for reducing pain and opioid use and improving physical function and QOL. Fusion with iFuse and Rialto appear to have similar effectiveness. AEs appear to be higher for minimally invasive SI joint fusion than conservative management through 6 months. Based on evidence from uncontrolled studies, serious AEs from minimally invasive SI joint fusion may be higher in usual practice compared to what is reported in trials. The incidence of revision surgery is likely no higher than 3.8% at 2 years. Limited evidence is available that compares different minimally invasive devices.
... In the past decade, the use of a minimally invasive transiliac or transarticular (lateral) approach became recognized with multiple high-level studies providing empirical support. [203][204][205][206][207][208][209][210][211] The use of the posterior approach has been recently proposed as a less invasive and safer procedure. Specifically, the posterior approach avoids the neurovascular bundle. ...
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Introduction: Painful lumbar spinal disorders represent a leading cause of disability in the US and worldwide. Interventional treatments for lumbar disorders are an effective treatment for the pain and disability from low back pain. Although many established and emerging interventional procedures are currently available, there exists a need for a defined guideline for their appropriateness, effectiveness, and safety. Objective: The ASPN Back Guideline was developed to provide clinicians the most comprehensive review of interventional treatments for lower back disorders. Clinicians should utilize the ASPN Back Guideline to evaluate the quality of the literature, safety, and efficacy of interventional treatments for lower back disorders. Methods: The American Society of Pain and Neuroscience (ASPN) identified an educational need for a comprehensive clinical guideline to provide evidence-based recommendations. Experts from the fields of Anesthesiology, Physiatry, Neurology, Neurosurgery, Radiology, and Pain Psychology developed the ASPN Back Guideline. The world literature in English was searched using Medline, EMBASE, Cochrane CENTRAL, BioMed Central, Web of Science, Google Scholar, PubMed, Current Contents Connect, Scopus, and meeting abstracts to identify and compile the evidence (per section) for back-related pain. Search words were selected based upon the section represented. Identified peer-reviewed literature was critiqued using United States Preventive Services Task Force (USPSTF) criteria and consensus points are presented. Results: After a comprehensive review and analysis of the available evidence, the ASPN Back Guideline group was able to rate the literature and provide therapy grades to each of the most commonly available interventional treatments for low back pain. Conclusion: The ASPN Back Guideline represents the first comprehensive analysis and grading of the existing and emerging interventional treatments available for low back pain. This will be a living document which will be periodically updated to the current standard of care based on the available evidence within peer-reviewed literature.
... This systematic review and meta-analysis included two RCTs and four PCSs, with a total of 564 patients. There were multiple studies regarding the same clinical trials (iMIA [23][24][25], INSITE [26,27], SIFI [28,29]) and so for each clinical trial, only the most recent article on the same clinical trial was included. Details of the literature review are shown in the PRISMA flowchart in Fig. 1, and the characteristics of selected studies are outlined in Table 1. ...
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Purpose Conduct a systematic review to quantify the effect of primary sacroiliac joint fusion (SIJF) for the treatment of sacroiliac (SI) joint pathology on patient reported outcomes. Methods Medline, Embase, Cochrane, PubMed, and Scopus databases were searched prior to August 18th, 2020 for all English-Language studies involving the treatment of SIJ pathology through SIJF and/or conservative management (CM). The quality of included studies was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE). Primary outcome measure was the Visual Analogue Scale (VAS) for low back pain. Secondary outcome measure was the Oswestry Disability Index (ODI) and the incidence of adverse reactions. Results A total of 564 patients and six studies were included. The overall quality of evidence analyzed by this review was low (GRADE = 0). Five out of the six studies were industry funded. The VAS standardized mean difference (SMD) between SIJF and CM at three months and six months follow-up was − 1.4 [95% confidence interval − 2.3, − 0.6] and − 1.5 [95% CI − 1.8, − 1.1]. The ODI SMD between SIJF and CM scores at three months and 6 months follow-up was − 0.9 [95% CI − 1.1, − 0.7] and − 1.1 [95% CI − 1.6, − 0.5]. The odds ratio of adverse reactions due to SIJF compared to CM was 1.9 [95% CI 0.1, 42.8]. Conclusion Based on the limited number of independent trials with long-term follow-up, SIJF shows potential as a surgical treatment option for SIJ pathology. PROSPERO registration CRD42020206149 (25th September 2020).
... Excessive micro-motion at the bone-implant interface may impair long-term bone ingrowth and ongrowth [26]. Similar 3D printed threadless implants have been successfully used for sacroiliac joint fusion [27][28][29], and in-vivo experiments have indicated that incorporating a porous surface can improve biological fixation and implant stability [7]. By referring the previous literatures related to the processing of the selective laser melted (SLM) machine used in this study, our anchor was designed to have porosities of 70% and pore sizes of 600 µm. ...
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Suture anchor fixation is a common method for securing bone and soft tissue in the body, with proven applications in the hip, elbow, hand, knee and foot. A critical limiting factor of suture anchors is the pull-out strength, particularly in suboptimal bone. This study introduces a novel 3D printed threadless suture anchor with a rectangular cross-section. The titanium anchor was designed with surface fenestration and a porous central core to improve bone ingrowth. The aim of this study was to compare the pull-out properties of the novel threadless anchor with a traditional circular threaded suture anchor. The anchors were inserted into a 0.24 g/cm3 synthetic cancellous bone block at angles of 90° and 135° to the surface. The sutures were pulled at 180° (parallel) to the surface under a static pull test (anchor pullout) and cyclic load test using a tensile testing machine. Under the static load, the greatest pullout strength was seen with the novel threadless anchor inserted at 90° (mean, 105.6 N; standard deviation [SD], 3.5 N). The weakest pullout strength was seen with the threaded anchor inserted at 90° (mean, 87.9 N; SD, 4.1 N). In the cyclic load test, all six of the threaded anchors with a 90° insertion angle pulled out after 18 cycles (70 N). All of the threadless anchors inserted at 90° survived the cyclic test (90 N). In conclusion, the novel threadless suture anchor with rectangular cross-section and traditional threaded suture anchor had similar pullout survivorship when inserted at either 90° or 135°. In addition, the 3D printed threadless anchor has the potential for good bone integration to improve long-term stabilization.
Study design: A case-control study. Objective: To evaluate the relationship between sacroiliac joint-related pain (SIJ-RP) and spinopelvic mobility. Summary of background data: No specific radiological findings are available for the diagnosis of SIJ-RP. A previous study reported that a higher pelvic incidence (PI) and sacral slope (SS) values were significantly associated with SIJP. The concept of spinopelvic mobility, which is evaluated by the differences between SS in the standing and sitting positions, has been the focus of hip and spine surgeries in recent years. Methods: The SIJ-RP group comprised patients diagnosed with SIJ-RP based on physical findings and their response to analgesic injections. No other lumbar or hip joint diseases were observed. The non-SIJ-RP group comprised patients with lower back pain (LBP) for reasons other than SIJ-RP. Radiographs of the lateral view of the pelvis in the standing and sitting positions were evaluated for all patients. We compared and analyzed the backgrounds, SS in the two positions, and difference in SS between the two positions in both groups. Results: In total, 245 patients were included in the study, with 49 and 196 patients in the SIJ-RP and non-SIJ-RP groups, respectively. More female patients experienced SIJ-RP than male patients (P=0.0361). There were significant differences between the groups for SS in standing (P=0.0076), sitting (P=0.0005), and those with a difference between sitting and standing of <5° (P=0.0278) in the univariate analyses. Logistic regression analyses, after adjustment for age and sex, revealed significant differences between the groups with an SS difference <5° (P=0.0088; 95% confidence interval, 1.280-5.519), with an odds ratio of 2.7. Conclusions: On evaluating spinopelvic mobility, we found that SIJ-RP was related to hypomobility of the sacrum, which could indicate the hypermobility of the SIJ.
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Purpose This review provides an overview of the patent literature on posteriorly placed intrapedicular bone anchors. Conventional pedicle screws are the gold standard to create a fixation in the vertebra for spinal fusion surgery but may lack fixation strength, especially in osteoporotic bone. The ageing population demands new bone anchors that have an increased fixation strength, that can be placed safely, and, if necessary, can be removed without damaging the surrounding tissue. Methods The patent search was conducted using a classification search in the Espacenet patent database. Only patents with a Cooperative Patent Classification of A61B17/70 or A61B17/7001 concerning spinal positioners and stabilizers were eligible for inclusion. The search query resulted in the identification of 731 patents. Based on preset inclusion criteria, a total of 56 unique patents on different anchoring methods were included, reviewed and categorized in this study. Results Five unique fixation methods were identified; (1) anchors that use threading, (2) anchors that utilize a curved path through the vertebra, (3) anchors that (partly) expand, (4) anchors that use cement and (5) anchors that are designed to initiate bone ingrowth. Of the anchor designs included in this study, eight had a corresponding commercial product, six of which were evaluated in clinical trials. Conclusion This review provides insights into worldwide patented intrapedicular bone anchors that aim to increase the fixation strength compared to the conventional pedicle screw. The identified anchoring methods and their working principles can be used for clinical decision-making and as a source of inspiration when designing novel bone anchors.
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Background: Sacroiliac (SI) joint pain conservative treatments show poor outcomes. Hypothesis: surgical treatment will show better results. Patients and methods: Prospective series: 24 patients undergoing SI fusion after failure of medical treatment and showing temporary relief with SI infiltration. Period: Nov 2009-July 2013. Gender: 9/15. 11 cases bilaterally (all ). Age: 32-71 years (mean 47.4 years). Height: 161-178 cm (mean 168.2 cm). Weight: 56-84 kg (mean 68.4 kg). Etiology: 12 degenerative/spontaneous, 7 fall on buttocks, 3 coincident with lumbar disc and 2 with lumbar posterolateral fusion. Exclusion criteria: ankylosing spondylitis, osteitis condensans ilii, sacro-iliac joint arthropaty. Demographics, analgesics and NSAID’s consumption, incidence and severity of complications, clinical outcome using a visual analog scale (VAS) for pain, Oswestry Disability Index (ODI) and time to returning to work were collected postoperatively at 1, 3 and 6 months, and then at six months interval until last follow-up. Results: Follow-up: 1-4.5 years (mean 23.3 months). No intra-operative or post-operative major complications. No blood transfusions. Patients stayed over-night, and discharged next morning. No crutches used. Time to returning to work: 47.4 days (range 30-67 days). Post-op: marked reduction in VAS and analgesic consumption (preop 8.7, post-op 1 month 3.2, 3 months 2.8, 6 months post-op 2.1, 12 months 1.7, 18 months 1.7, 2 years 1.9, 2½ years 1.8, 3 years 2.0, at 3½ years 2.1, 4 years 2.1 and 4½ 2.1). Mean ODI scores improved from 54.1 preoperatively to 23.9, 21.2, 20.4 and 14.3 at 1, 3, 6 and 12 months postoperatively, and 15.1, 15.5 15.8, 16.0, 16.1, 16.3 and 16.3 at 1½, 2, 2½, 3, 3½, 4 and 4½ years (p<.001). 1 year post-op 22/24 patients would undergo the procedure again. Conclusion: Percutaneous SI joint arthrodesis is effective and safe to treat chronic SI joint pain.
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Background context: Although pain is generally regarded as originating in the lumbar spine, it has been estimated that in 15-30 % of patients, LBP originates from the sacroiliac joint (SIJ). Purpose: To determine whether sacroiliac joint fusion (SIJF) for LBP is effective in reducing pain when the SIJ is known to be the pain generator. Study design/setting: Systematic review and meta-analysis. Methods: A systematic literature review and meta-analysis was performed of observational studies describing outcome of SIJF in patients with LBP. Outcome measures were VAS pain, ODI, SF-36 PCS/MCS and Majeed score. The following databases were searched: PubMed, Web of Science, Embase, Medline and Google scholar. The methodological quality of selected studies was assessed using the National Heart Lung and Blood Institute case series quality assessment tool. Meta-analysis was used to combine the studies for each outcome and forest plots were prepared. Outcomes were expressed as mean difference (MD). Results: Six studies were included in the meta-analysis with a mean follow-up of 17.6 months. All outcomes showed statistical and clinical improvement (VAS pain MD: 54.8; 95 % CI 48.6, 61.0; n = 380; p < 0.001, ODI MD: 14.5; 95 % CI 8.4, 20.6; n = 102; p < 0.001, SF-36 PCS MD: -19.5; 95 % CI -24.7, -14.2; n = 140; p < 0.001, SF-36 MCS MD: -8.5; 95 % CI -12.9, -4.1; n = 198; p < 0.001 and Majeed score MD: -35.4; 95 % CI -48.5, -22.2; n = 140; p < 0.001). Conclusions: SIJF appears to be a satisfactory procedure for alleviating pelvic girdle pain.
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Introduction: Surgical revision rate is a key outcome with all permanent implants. The iFuse Implant System(®) is a permanent implant used to perform minimally invasive sacroiliac joint fusion. The purpose of this study is to determine the surgical revision rate after sacroiliac joint fusion surgery with this system. Methods: Using two internal sources of information, revision surgeries were identified and linked to index surgeries. The likelihood of revision surgery was calculated using the Kaplan-Meier life table approach. Predictors of revision were explored. Results: Four-year survivorship free from implant revision was 96.46%. Revision rate did not differ by sex and was lower for age >65. In all, 24% of revisions occurred within the first 30 days after surgery; 63.5% occurred within year 1. Implant survivorship has improved annually since the device was introduced in 2009. Conclusion: The survivorship rate with this implant is high and improving; the rate is somewhat higher than total hip replacement but lower than that of lumbar spine procedures.
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Study Design Prospective multicenter single-arm interventional clinical trial. Objective To determine the degree of improvement in sacroiliac (SI) joint pain, disability related to SI joint pain, and quality of life in patients with SI joint dysfunction who undergo minimally invasive SI joint fusion using triangular-shaped titanium implants. Methods Subjects (n = 172) underwent minimally invasive SI joint fusion between August 2012 and January 2014 and completed structured assessments preoperatively and at 1, 3, 6, and 12 months postoperatively, including a 100-mm SI joint and back pain visual analog scale (VAS), Oswestry Disability Index (ODI), Short Form-36 (SF-36), and EuroQOL-5D. Patient satisfaction with surgery was assessed at 6 and 12 months. Results Mean SI joint pain improved from 79.8 at baseline to 30.0 and 30.4 at 6 and 12 months, respectively (mean improvements of 49.9 and 49.1 points, p < 0.0001 each). Mean ODI improved from 55.2 at baseline to 32.5 and 31.4 at 6 and 12 months (improvements of 22.7 and 23.9 points, p < 0.0001 each). SF-36 physical component summary improved from 31.7 at baseline to 40.2 and 40.3 at 6 and 12 months (p < 0.0001). At 6 and 12 months, 93 and 87% of subjects, respectively, were somewhat or very satisfied and 92 and 91%, respectively, would have the procedure again. Conclusions Minimally invasive SI joint fusion resulted in improvement of pain, disability, and quality of life in patients with SI joint dysfunction due to degenerative sacroiliitis and SI joint disruption.