Minimally Invasive Sacroiliac Joint Fusion Using Triangular Titanium versus Cylindrical Threaded Implants: A Comparison of Patient-Reported Outcomes

BACKGROUND: Minimally invasive fusion of the sacroiliac (SI) joint has gained popularity for the treatment of refractory dysfunction. The purpose of this study was to compare the clinical outcomes of minimally invasive SI joint fusion between cylindrical threaded implants (CTIs) and triangular dowel implants (TDIs). METHODS: We retrospectively reviewed consecutive patients who underwent SI joint fusions with either CTIs or TDIs. Data collected included patient demographics, peri-operative data, and all patient-reported outcomes (PROs) including postoperative visual analog scale (VAS), Oswestry Disability Index, and Short Form-12 at 6 months and 1 year. The change from baseline PROs between the cohorts was analyzed as the primary outcome. Secondary outcomes included revision rates and time to revision between the two cohorts. A P value <0.05 was considered significant. RESULTS: One hundred fifty-six consecutive patients underwent SI joint fusion, 74 patients with CTIs and 82 with TDIs. There was a significant difference in procedure length with CTI averaging 60.0 minutes (confidence interval: 55.7-64.3) and TDI averaging 41.2 minutes (confidence interval: 38.4-43.9, P< 0.0005). In both cohorts, there was a significant improvement in all PROs at 6 months when compared with preoperative values. However, when compared, there was no significant difference between the cohorts at 6-month follow-up or 1-year follow-up for either VAS-back, VAS-leg, Oswestry Disability Index, or Short Form-12. A 6.1% revision rate in the CTI cohort was observed compared with a 2.4% revision rate in the TDI cohort (P = 0.11). CONCLUSIONS: SI joint fusions with TDI or CTI offer a significant improvement in pain, disability, and quality of life. However, no difference was observed between devices to suggest superior clinical outcomes. Increased revision rates in the Rialto group warrants further investigation.