Spinal Fracture in Patients With Ankylosing Spondylitis: Cohort Definition, Distribution of Injuries, and Hospital Outcomes.

STUDY DESIGN A retrospective cohort. OBJECTIVE The aim of this study was to characterize spinal fractures in patients with ankylosing spondylitis. SUMMARY OF BACKGROUND DATA Patients with ankylosing spondylitis are susceptible to fractures of the spinal column, even from minor trauma. However, the literature describing patients with ankylosing spondylitis and spinal fractures consists largely of case reports and small case series. The purpose of this study is to better characterize fractures of the ankylosed spine, including the patient population, locations of fracture, and outcomes in a large, nationally representative sample. METHODS All patients with diagnoses of both fracture of the spinal column and ankylosing spondylitis admitted between 2005 and 2011 were identified in the National Inpatient Sample (NIS). Patient demographics, fracture regions, and complications were characterized with descriptive statistics. The associations between injury characteristics and outcomes were assessed using Poisson regression. RESULTS A total of 939 patients with ankylosing spondylitis admitted with a spinal fracture were identified in NIS. The average age was 68.4 ± 14.7 years, and 85% of patients were male. Cervical fractures were the most common (53.0%), followed by thoracic (41.9%), lumbar (18.2%), and sacral (1.5%). Spinal cord injury was present in 27.5% of cervical fractures, 16.0% of thoracic fractures, and 21.1% of cases overall. Fractures involving more than 1 region of the spine occurred in 13.1% of patients. Patients were treated with fusion in 49.9% of cases. In-hospital adverse events occurred in 29.4% of patients, and 6.6% of patients died during their admission. CONCLUSION More than 10% of patients had fractures in more than 1 region of the spine. There is a high risk of adverse events in this population, and 6.6% of patients died during their inpatient stay. These results provide clinicians with a better understanding of the distribution and the high morbidity and mortality of fractures in the ankylosed spine. LEVEL OF EVIDENCE 3.