Managing fractures of the ankylosed spine

The ankylosed spine is prone to fracture after minor trauma due to its changed biomechanical characteristics. Although spinal fractures in patients with ankylosing spondylitis (AS) are a well-known and feared complication, many physicians do not know that advanced diffuse idiopathic skeletal hyperostosis (DISH) may also lead to complete ankylosis of the spine and, as a result, to an increased fracture risk. The prevalence of AS is stable, but DISH may become more widespread due to its association with older age, obesity and type 2 diabetes mellitus. Because fractures in spines affected by ankylosing spinal disorders (ASDs) frequently involve the anterior/middle/posterior elements, they tend to be highly unstable and frequently lead to (secondary) neurological deficits. Clinical outcomes in patients with fractures in ankylosed spines are considerably worse compared with the general trauma population. This article aims to describe AS and DISH, the two most important disorders leading to spinal ankylosis, and give recommendations for the management and treatment of fractures in ASD patients.