iMIA results mirror INSITE for SI-Bone’s iFuse minimally invasive sacroiliac joint fusion

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The European Spine Journal has published six-month results from iMIA (iFuse Implant System Minimally Invasive Arthrodesis). iMIA is a randomised controlled trial conducted in Europe to measure the safety and effectiveness of minimally invasive sacroiliac joint fusion using iFuse (SI-Bone) implants, compared to conservative management in patients with chronic sacroiliac joint dysfunction.

iMIA is the second randomised controlled trial comparing iFuse to conservative therapy. Results and results from iMIA mirror those of INSITE, an earlier multicentre randomised controlled trial performed in the USA. Both trials were performed in the post-market setting and used very similar inclusion and exclusion criteria, according to a SI-Bone press release. Study entry criteria were designed to reflect real-world clinical practice.


The publication reports results on 103 patients with chronic sacroiliac joint pain enrolled at nine centres in four European countries. Study subjects were randomly assigned to either sacroiliac joint fusion with iFuse (n=52) or to conservative therapy (n=51). Conservative therapy was performed according to the European guidelines for the diagnosis and management of pelvic girdle pain and consisted of optimisation of medical therapy, individualised physical therapy, 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 at six months. Additional endpoints included quality of life using EQ-5D-3L, disability using Oswestry Disability Index (ODI), sacroiliac joint function using active straight leg raise (ASLR) test, and adverse events.

In the study, sacroiliac joint fusion provided superior improvement in pain, disability, function and quality of life compared to conservative management.  Mean low back pain improved by 43.9 points in the sacroiliac joint fusion group compared to 5.7 points in the conservative therapy group (difference of 38.2 points, p<.0001) (see Figure 1). Mean ODI improved by 26 points in the sacroiliac joint fusion group and 6 points in the conservative therapy group (p<.0001) (see Figure 2).  ASLR, EQ-5D-3L, walking distance and satisfaction were statistically superior in the subjects treated by sacroiliac joint fusion. The frequency of adverse events did not differ between groups.

The iMIA trial extends the findings from prior studies in two aspects, according to SI-Bone. First, iMIA included two functional assessments (walking distance and sacroiliac joint function via ASLR), neither of which had been previously reported; both showed improvement in the sacroiliac joint fusion group but not in the conservative therapy group. Second, conservative therapy was provided per European treatment guidelines, meaning that the control group intervention may have been more standardised than in prior trials.

“Results from iMIA provide additional, independent confirmation that the improvements after iFuse surgery are clinically important and statistically superior to those seen with continued conservative care,” said Bengt Sturesson, from Ängelholm Hospital, Ängelholm, Sweden, lead author of the paper. “Furthermore, results from iMIA, combined with the INSITE randomised control trial, as well as four- and five-year outcomes from other published cohorts, suggest that minimally invasive sacroiliac joint fusion with iFuse can be added to the portfolio of typical spinal surgeries that European surgeons can now offer their patients.”