Sacroiliac joint fusion: incidence, timing, and risk factors for contralateral fusion

Contralateral SIJF occurs in 21% of patients who have undergone initial unilateral SIJF, with over 90% of cases occurring within 18 months of the initial ipsilateral fusion procedure. Bilateral SIJ pain prior to initial SIJF and prior L5-S1 fusion are key predictors of contralateral surgery. Patients with bilateral SIJ pain had elevated BMI. These findings highlight the importance of early identification of high-risk patients to inform treatment decisions and potentially improve outcomes.