Risk of Total Hip Arthroplasty After Sacroiliac Joint Fusion Surgery: A Nationwide Study

Study DesignRetrospective Cohort Study.ObjectiveTo investigate whether patients with hip osteoarthritis (OA) who underwent sacroiliac joint (SI) fusion were at increased risk of subsequent total hip arthroplasty (THA) compared to matched controls.MethodsThis retrospective cohort study utilized the PearlDiver Mariner Database, a nationwide insurance claims dataset encompassing approximately 157 million patients. Patients with hip OA who underwent SI joint fusion were identified and propensity-matched 1:1 to controls with hip OA alone based on age, sex, and Elixhauser Comorbidity Index. A landmark analysis was employed to mitigate immortal time bias, with patients undergoing THA within two years of hip OA diagnosis excluded. Patients undergoing lumbar fusion surgery during this time period were also excluded. Univariable and multivariable logistic regression and Kaplan-Meier survival analyses were performed to assess the likelihood of subsequent THA.ResultsFollowing propensity matching, 4,383 patients per cohort were analyzed. SI fusion was independently associated with a significantly higher likelihood of subsequent THA on both univariable and multivariable analysis (OR: 2.18 [95% CI 1.60-2.96]; P < 0.001). THA-free survival at 10 years was 94.7% in the SI fusion group versus 96.8% in controls (p =0.007).ConclusionPatients with hip OA who underwent SI fusion demonstrated a significantly higher likelihood of requiring subsequent THA, suggesting that SI fusion may accelerate hip OA progression through adjacent segment biomechanical changes. These findings have important implications for preoperative counseling in patients with concomitant hip OA and SI dysfunction.