iFuse Titanium Implant System Shows Efficacy and Safety in 2-Year Study

The iFuse minimally invasive system for sacroiliac joint fusion was associated with significant improvements in pain, disability, and quality of life at 2-years postsurgery.

colorful chartThe iFuse minimally invasive system for sacroiliac (SI) joint fusion was associated with significant improvements in pain, disability, and quality of life at 2-years postsurgery in a prospective multicenter clinical trial published in the International Journal of Spine Surgery. The SI joint fusion system also was linked to decreased use of opioids in patients taking these agents at baseline.

"The patient satisfaction rate in this study was more than 90%, which is very encouraging and fits along with what most of us are seeing anecdotally in our clinical practices," explained lead author Bradley S. Duhon, MD, who is Assistant Professor of Neurosurgery at the University of Colorado in Aurora, CO.

"SI joint fusion with triangular titanium [implants] is a reasonable option to help achieve long-term pain relief for sacroiliitis in patients who have failed conservative measures," commented Joshua Ammerman, MD, who is a Neurosurgeon at Washington Neurosurgical Associates in Washington, DC, and a member of the SpineUniverse Editorial Board.

Study Rationale
"SI joint fusion has gotten a bad reputation because traditional techniques had a high complication rate and an overall fairly low success rate," Dr. Duhon noted. The introduction of minimally invasive alternatives to open SI joint fusion were met with skepticism early on; however, initial retrospective studies showed promise, Dr. Duhon told SpineUniverse. The current prospective study was designed to address the questions of safety and efficacy, and also to provide evidence to insurance companies that the iFuse system is a worthwhile intervention, Dr. Duhon said.

The study included 172 patients (mean age, 50.9 years; 69.8% female) with SI joint dysfunction implanted with the iFuse system at one of 26 sites. In all patients, SI joint dysfunction was a direct result of degenerative sacroiliitis (78.5%) or SI joint disruption (21.5%), the conditions for which this device is indicated. Exclusion criteria included osteoporosis, severe back pain due to other causes, chronic rheumatologic condition or chondropathy, titanium allergy, disability leave, receiving workers' compensation related to back or SI joint pain, among other factors.

The primary endpoint was treatment success as defined using the following criteria: reduction from baseline visual analog scale (VAS) SI joint pain ≤20 points, absence of device-related serious adverse events, absence of neurological worsening related to the sacral spine, and absence of surgical reintervention for SI joint pain.

High Success Rate Found
As shown in the Table 1, significant improvements in pain, disability, and quality of life was found at 24 months post-surgery. The overall success rate in an intent-to-treat population was 80.2%. The success rate was not affected by underlying diagnosis, a history of prior lumbar fusion, smoking status, or unilateral vs bilateral SI joint fusion.

All 37 patients prescribed opioids before surgery no longer need these agents by month 24 post-treatment. In contrast, 7 patients who were not initially taking opioids began taking them after surgery, including 2 subjects who underwent contralateral SI joint fusion after the index surgery, 1 who had recently undergone revision surgery, and 1 who had back pain resulting from a fall 5 months after SI joint fusion.

efficacy outcomes from iFuse implant sytem for SI fusion at 2-years
Radiographic Evidence of Early Fusion
Computed tomography images taken at 1 year showed that 97% of patients had evidence of bone adherence (covering at least >30% of the implant surface area) to at least 2 of the implants on both the iliac and sacral sides. The majority of patients (>80%) showed bone remodeling in the treated SI joint, and a minority (n=39; 22%) showed evidence of bridging bone.

"The authors have reported their 2-year follow-up data of a prospective multicenter study examining the clinical utility and radiographic outcomes for triangular titanium devices for sacroiliac fusion," Dr. Ammerman commented. "The investigators have demonstrated high rates of pain relief for SI joint dysfunction treated with this less invasive technique as manifest by persistent statistically significant reductions in VAS, ODI, and SF-36 at 24 months postoperatively."

"Rates of radiographic fusion were not high; but when examined in concert with the excellent pain relief achieved appear to indicate that immobilization of the SI joint, in the absence of bony fusion, is adequate to achieve pain relief," Dr. Ammerman told SpineUniverse.

Safety Outcomes
The revision rate was 4.7%, which Dr. Duhon said is considered an acceptable overall low rate compared with cervical or lumbar instrumentation. This revision rate is consistent with multiple published studies of the iFuse system, Dr. Duhon noted.

A total of 454 adverse events in 153 subjects were reported, the majority of which were unrelated to the device or the procedure. In fact, only 7 patients experienced device-related adverse events. Seventy-three of the adverse events were considered severe. The most common serious adverse events related to the device or procedure were recurrent/persistent pain due to suboptimal implant position (2), neuropathic pain due to implant-related nerve irritation requiring revision (1), and severe postoperative pain requiring hospitalization (1).

"The fairly high complication rate seen in this study speaks to the learning curve and technical demand associated with this procedure," Dr. Ammerman said. "In my personal experience with SI joint fusion, the addition of spinal navigation can help to mitigate the issue of device malpositioning."

Challenges in Managing SI Joint Dysfunction
Dr. Ammerman emphasized that the greatest challenge in treating SI joint pain "is making the diagnosis and maintaining a high index of suspicion, particularly in those patients with a prior lumbar fusion, particularly at L5-S1 where the SI joint is under greater stress."

Dr. Duhon added that once the diagnosis is made, patients should attempt all nonsurgical interventions before considering SI joint fusion. These interventions may include physical therapy, anti-inflammatory agents, lifestyle modifications, joint injections, and, in some cases, rhizotomy.

"Only when all those methodologies have failed, and your pain is significant enough to where it is negatively impacting your quality of life do you become a surgical candidate," Dr. Duhon said.

Updated on: 05/19/16
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