2021 Association of Spinopelvic Parameters With Positive Predictors of Sacroiliac Joint Fusion Success

INTRODUCTION: Sacroiliac joint (SIJ) dysfunction is an underdiagnosed entity with increasing prevalence in patients with prior lumbosacral fusion. Currently, SIJ dysfunction is primarily a clinical diagnosis with lack of radiographic parameters to support standard of care surgical decision making to undergo SIJ fusion. METHODS: This is a single center, retrospective analysis on open and minimally invasive SIJ fusion cases between 2016 and 2022. Patient demographics, clinical characteristics, and pre-operative spinopelvic parameters were collected. Primary outcome was the need for revision SIJ fusion. Univariate and multivariate analysis was performed to identify predictors of revision. RESULTS: A total of 42 cases were included in the analysis with mean age 58.8 + 12.3 years, 78.6% female, and mean body mass index (BMI) of 31.0 + 6.8. There were 20 (47.6%) cases which underwent revision surgery. The revision group had a significantly lower pre-operative pelvic incidence (57.4 vs 63.4 degrees, p = 0.05), pelvic incidence-lumbar lordosis mismatch (11.2 vs 18.8 degrees, p = 0.02), and pelvic tilt (21.1 vs 25.9 degrees, p = 0.04). Multivariate analysis demonstrated higher pelvic incidence was associated with significantly lower odds of SIJ fusion revision (p = 0.035). CONCLUSIONS: SIJ dysfunction is currently a clinical diagnosis without accepted radiographic parameter that supports surgical indication for SIJ fusion. This study suggests that pre-operative spinopelvic parameters, specifically higher pelvic incidence, pelvic tilt, and pelvic incidence-lumbar lordosis mismatch may be associated with positive outcome after SIJ fusion leading to lower revision rate. Further studies evaluating the relationship between spinopelvic parameters and SIJ fusion success may provide radiographic guidance in surgical decision making for SIJ fusion.