Minimally Invasive Posterior SI Joint Fusion with a Novel Cortical Allograft: Real-World, Long-Term, Outcomes from a Large, Multisite US Cohort

Purpose: Sacroiliac (SI) joint dysfunction accounts for 15% to 30% of reported low back pain. Primary treatments of SI joint dysfunction include medications, bracing, physical therapy, injections, and ablations. When primary non-surgical treatments are unsuccessful, fusion or stabilization may be considered. Here, we report a multicenter study aimed to evaluate real-world outcomes of posterior sacroiliac joint fusion using cortical allograft across six United States clinical sites. Methods: Patients diagnosed with sacroiliitis through physical examination and diagnostic injection who have failed conservative management that ultimately underwent percutaneous allograft implant with at least 6 months of follow up were included. Data extracted from electronic health records included demographic and clinical characteristics, Numeric Rating Scale (NRS) pain scores, and patient-reported adverse events. Descriptive statistics were utilized to summarize baseline characteristics, and proportion of patients achieving minimally clinically important difference (MCID) was assessed. Paired t-tests were employed to compare pre-operative and post-operative outcomes. Results: A total of 258 patients were included. Of these, 63.9% were women and 36.1% were men, with a mean age of 69.2 years and an average body mass index of 29.6 kg/m². Average NRS at baseline was 7.61 ± 1.64 and 1.60 ± 1.86 (p < 0.05) at last follow-up visit. The mean pain reduction from baseline to the last follow-up (91.2 week mean or 1.75 years) was 6.01 points, exceeding MCID. The safety profile was favorable, with no serious adverse events reported in this cohort. Conclusion: Our findings affirm that posterior SI joint fusion constitutes an effective and enduring treatment option for patients suffering from SI joint dysfunction unresponsive to conservative care. The results indicate that posterior SI joint fusion is safe and effective at achieving sustained pain relief. Our findings are congruent with previously published studies and provide further evidence of sustained durable pain outcomes.