SI Joint Fusion Linked to Fewer Revision Surgeries Versus SI Joint Fixation

Timothy Holt, MD, reports on his spine center's surgical experience

When a surgeon at the Montgomery Spine Center switched from sacroiliac (SI) joint fixation with screws to SI joint fusion using the iFuse Implant System® (SI-BONE, Inc), he found that fewer patients returned with continued SI joint pain and needing surgical revision.

A recent retrospective study by this surgeon confirmed that the anecdotal evidence was true. Indeed, 4-year cumulative probability of revision surgery was 30.8% with SI joint fixation compared with 5.7% with SI joint fusion, as reported in the International Journal of Spine Surgery.

“Long-term, SI joint fixation does not give as good an outcome as SI joint fusion,” explained coauthor Timothy Holt, MD, an orthopedic surgeon at Montgomery Spine Center in Montgomery, Alabama.

The study, which was sponsored by SI-BONE, involved all 38 patients who underwent SI joint fixation with cannulated screws and 274 patients who underwent SI joint fusion with the iFuse system between 2003 and 2015 at Montgomery Spine Center. Dr. Holt performed all the procedures, and all patients were at least 19 years of age at the time of surgery.

medical report, tablet, pen, glasses, dataOverall, 19 patients in the fixation group and 12 patients in the fusion group underwent SI joint revision surgery, most commonly for pain recurrence. Photo

Nearly Two-Thirds of the SI Joint Fixation Group Required Revision Surgery

Overall, 19 patients in the fixation group and 12 patients in the fusion group underwent SI joint revision surgery, most commonly for pain recurrence. Using survival analysis techniques, the investigators calculated that the cumulative probably of revision was lower in the fusion group than in the fixation group (P<0.0001).

The cause underlying the need for revision surgery in the fixation group was primarily loosening of screws and recurrence of pain. In the fusion group, the cause was traumatic failure of the iliac wing secondary to a fall (one patient), malposition of the implant, and loosening of the implant(s).

Subgroup analysis showed the type of implant used (iFuse versus screw) was the only predictor of revision surgery.

“The design of the iFuse implant contributes significantly to the improved outcomes found in this study, in that the implant allows for bony ingrowth, and its triangular shape prevents rotational motion of the joint,” Dr. Holt told SpineUniverse.

“Screw fixation, in my opinion, changes the center of rotation,” Dr. Holt said. “We know that the SI joint moves in nutation, so if you put screws into that same plane of motion as the joint,” there is greater chance for the screws to loosen, Dr. Holt explained.

Study Limitations

Study limitations included a shorter followup in the fusion group than in the fixation group, inability to locate records in 9 patients in the fixation group and 11 patients in the fusion group, and lack of contact with 5 patients in the fixation group and 7 patients in the fusion group.

Overall, Dr. Holt concluded that the study provides additional data supporting the need to consider SI joint dysfunction in patients with ongoing low back pain.

“Finally, we have gotten to the point where we are beginning to appreciate the SI joint as a pain generator, which is something that I think had been overlooked for quite some time,” Dr. Holt concluded.

Disclosure: Dr. Holt is a consultant to SI-BONE. Ms. Spain has no financial conflict.

Updated on: 05/11/19
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