Abstract
PURPOSE: Sacroiliac joint (SIJ) changes due to ankylosis may influence the fracture pattern of the posterior ilium, an essential component of the posterior ring. This study aimed to assess the association between SIJ ankylosis and posterior ilium fractures (PL) in pelvic ring injuries. MATERIALS AND METHODS: A retrospective analysis was conducted on 272 patients diagnosed with pelvic ring injuries between January 2004 and October 2023. Patients were categorized into non-ankylosed (n=185) and ankylosed (n=87) SIJ cohorts. The prevalence of SIJ ankylosis in our study sample was 32.0% (87/272). Patient demographics, SIJ ankylosis, PL, and fracture classification using computed tomography were compared between the two groups. PL was defined as any type of posterior ring injury with fracture lines extending to the region posterior to the iliac pillar, with or without SIJ subluxation or dislocation. To determine the association between SIJ ankylosis and PL, a logistic regression analysis adjusted for age, body mass index, sex, and energy of injury mechanism was performed. RESULTS: Our results found that the ankylosed group had a higher PL ratio (47.1% vs. 31.4%, P=0.012), was older (64.9 years vs. 53.5 years, P<0.001), and included more males (58.6% vs. 37.8%, P=0.001) than the non-ankylosed group. Multivariate analysis revealed a significant association between SIJ ankylosis and PL (odds ratio 2.15, P=0.022). CONCLUSION: This study determined that SIJ ankylosis is significantly associated with PL in pelvic ring injuries; transformed SIJ may contribute to changes in posterior ring fracture patterns.