Comparative Outcomes of Posterior and Lateral Sacroiliac Joint Fusions from a Single Academic Pain Center.

BACKGROUND: Sacroiliac (SI) joint dysfunction is a common source of chronic low back pain. Minimally invasive SI joint fusion techniques, including posterior interpositional and lateral transiliac approaches, have emerged as treatment options for patients who fail conservative management; however, comparative real-world outcome data, particularly from procedures performed by interventional pain physicians, are limited. OBJECTIVES: We aimed to evaluate short-term outcomes, complication rates, and revision rates of posterior interpositional vs lateral transiliac SI joint fusion performed by interventional pain physicians at a single academic medical center. STUDY DESIGN: Retrospective cohort study. SETTING: Patients were treated at a pain management clinic within an academic medical center. METHODS: A retrospective review was performed of patients' records who underwent SI joint fusion from January 1, 2020 through May 23, 2025. Patients were identified using Current Procedural Terminology codes 27278 and 27279. Demographic data, procedural characteristics, perioperative outcomes, pain scores, and revision surgeries data were collected. Outcomes included preoperative and postoperative month one Visual Analog Scale scores, percentage of pain relief, estimated blood loss, complications, and need for revision surgery. Comparative analyses between posterior and lateral approaches were performed using appropriate statistical tests with statistical significance set at P < 0.05. RESULTS: Eighty patients were included; 33 had posterior interpositional fusion and 47 had lateral transiliac fusion. There were no statistically significant differences in baseline demographics between groups. Both approaches resulted in clinically meaningful short-term pain improvement, with mean Visual Analog Scale scores improving from a preoperative score of 6.6 cm to 3.4 cm at postoperative month one. The posterior interpositional group demonstrated a statistically significant higher revision rate due to loss of efficacy compared with the lateral transiliac group (18.2% vs 0%, P = 0.003). Estimated blood loss and complication rates were low for both approaches. LIMITATIONS: Our study is limited by its retrospective design, small sample size, and variable follow-up duration. Standardized pain scores and percentage pain relief beyond the one-month postoperative visit were not consistently documented and therefore could not be reliably analyzed. CONCLUSION: Both posterior interpositional and lateral transiliac SI joint fusion performed by interventional pain physicians provided meaningful short-term pain relief in appropriately selected patients. A higher revision rate was observed in the posterior interpositional group, suggesting potential differences in procedural durability. Prospective, adequately powered studies are needed to further define long-term outcomes and optimize procedural selection for managing SI joint-mediated pain.