Two-year results from SIFI (Sacroiliac Joint Fusion with iFuse Implant System)—a prospective multicentre clinical trial of SI joint fusion—have been published in The International Journal of Spine Surgery.
The trial included 172 subjects at 26 US centres, and was authored by Bradley Duhon, University of Colorado (Boulder, USA) and others. Two-year results show marked improvements in sacroiliac joint pain, disability. Quality of life achieved at six and 12 months were maintained to two years.
Outcome assessments included an intent-to-treat primary success/failure composite endpoint at six months that consisted of a reduction from baseline visual analogue scale sacroiliac joint pain of at least 20 points, absence of device-related serious adverse events, absence of neurological worsening related to the sacral spine, and absence of surgical reintervention for sacroiliac joint pain. Secondary endpoints included success rates at other time points, improvement from baseline in visual analogue scale sacroiliac joint pain, Oswestry Disability Index, Short Form-36 and EuroQuol-five dimension scores.
Success rates were 80.2% at six months and remained high at 79.9% at both the 12- and 24-month follow-up. Mean sacroiliac joint pain improved from 79.8 at baseline to 28.1 at 12 months and remained low at 26.0 at 24 months (see Figure 1). ODI decreased from 55.2 at baseline to 31.5 at 12 months and remained low at 30.9 at 24 months (see Figure 2). Quality of life improvements seen at 12 months were maintained at 24 months.
Furthermore, although the trial did not have the specific goal of opioid use reduction, and patients were not required to participate in a structured drug reduction program, results showed a decrease in opioid use of 28% by month 24. Thirty-seven patients who were taking opioids at baseline had stopped taking them at month 24.
The surgical revision rate was low with eight subjects having revision surgery (4.7%) and there were seven device-related adverse events. Radiographic analysis was performed via computed tomography scans at one year and showed a high rate of bony apposition to at least two implants on both the iliac and sacra sides with greater than 30% implant surface area coverage on each side of the SI joint.
“The target patient population and study eligibility criteria for SIFI were identical to INSITE, a prospective multicentre randomised controlled trial of iFuse vs. non-surgical management,” says Danny Cher, vice president of Clinical Affairs at SI-Bone. “INSITE showed superiority of iFuse compared to non-surgical management at nearly every endpoint at one year and SIFI at two years is an excellent proxy for INSITE two-year results which are expected to be published this summer.”