Short- to mid-term outcomes after spinopelvic and sacroiliac screw fixation for unstable sacral fractures: a retrospective cohort study.

BACKGROUND: Unstable sacral fractures require reliable posterior stabilization, but the choice between sacroiliac screw fixation and spinopelvic fixation is influenced by fracture morphology, neurological status, and reducibility. This study described short- to mid-term outcomes after these procedures in clinically selected patients. METHODS: This retrospective single-center cohort included patients with unstable sacral fractures without spinopelvic dissociation who underwent SIS or SPF between January 2022 and January 2025. Pain was assessed using the Numerical Rating Scale at one and three months. ODI, Majeed score, leg-length discrepancy, neurological outcomes, and complications were evaluated at follow-up. Exploratory analyses adjusted for Denis classification. RESULTS: A total of 44 patients were analyzed. NRS scores decreased significantly over time in both groups, F(1,42) = 141.86, p < 0.001, partial η² = 0.772, without a significant time-by-group interaction, F(1,42) = 0.72, p = 0.400. Final ODI scores were 39.88 ± 23.15 after SIS and 42.83 ± 19.82 after SPF; the adjusted mean difference was - 4.12 points, 95% CI - 17.06 to 8.83, p = 0.524. Median Majeed scores were 34.0 and 41.5, respectively, p = 0.288; the adjusted difference was - 6.82 points, 95% CI - 19.04 to 5.40, p = 0.266. Mean leg-length discrepancy was 5.62 ± 4.29 mm versus 8.50 ± 5.47 mm, mean difference - 2.88 mm, 95% CI - 5.84 to 0.09, p = 0.057. Implant removal occurred in 11.5% and 33.3%, respectively, p = 0.128. CONCLUSION: Both techniques were associated with acceptable postoperative outcomes in appropriately selected patients. However, selection bias, residual confounding, and limited power preclude conclusions regarding superiority or equivalence.