Spine Fractures of Patients with Ankylosing Spondylitis and Diffuse Idiopathic Skeletal Hyperostosis: Fracture Severity and Injury-Related Mortality at a Level I Trauma Center

STUDY DESIGN: Retrospective review of prospectively collected cohort. PURPOSE: To identify differences in treatment and mortality of spine fractures in patients with ankylosing conditions of the spine. OVERVIEW OF LITERATURE: Ankylosing spondylitis (AS) and diffuse idiopathic skeletal hyperostosis (DISH) are the two most common etiologies of ankylosing spinal disorder (ASD). However, studies on the treatment and outcomes of spine fractures in AS and DISH patients remain few. METHODS: Patients presenting with a spine fracture were diagnosed with AS or DISH at a single tertiary care center between 2010 and 2019. We excluded those who lacked cross-sectional imaging or fractures occurring at spinal segments affected by ankylosis, as well as polytraumatized patients. Patient demographics, injury mechanism, fracture level, neurologic status, treatment, and 1-year mortality were recorded. Computed tomography imaging was reviewed by two independent readers and graded according to the indicated AO Spine Injury Classification System. Differences in fracture severity, treatment method, and mortality were examined using Student t-tests, chi-square tests, and two-proportion Z-tests with significance set to p<0.05. RESULTS: We identified 167 patients with spine fracture diagnosed with AS or DISH. Patients with AS had more severe fractures and more commonly had surgery than patients with DISH (p<0.001). Despite these differences, 1-year mortality did not significantly differ between AS and DISH patients (p=0.14). CONCLUSIONS: Although patients with AS suffered more severe fractures compared to DISH and more frequently underwent surgery for these injuries, outcomes and 1-year mortality did not differ significantly between the two groups. For patients with ASDs and fractures, outcomes appear similar regardless of treatment modality. Consequently, there may be an opportunity for critical reappraisal of operative indications in ASD and a larger role for nonoperative management in these challenging patients.