Syndesmophyte growth in ankylosing spondylitis

Purpose of review Syndesmophytes are characteristic components of the spine disorder of ankylosing spondylitis. Understanding their growth may reveal insights to pathogenesis and potential treatment. We review recent studies on rates of development of syndesmophytes, patient characteristics associated with more rapid syndesmophyte growth, local vertebral abnormalities that precede syndesmophytes, systemic biomarkers of syndesmophytes, and studies of medications. Recent findings New syndesmophytes develop in one-third of patients over 2 years. Consistent clinical predictors are male sex, elevated serum C-reactive protein levels, and preexisting syndesmophytes. Concomitant vertebral inflammation and fat dysplasia on MRI predict future syndesmophytes at the same vertebral location, but most syndesmophytes do not have recognized antecedents. Associations with serum levels of Wingless pathway proteins are inconsistent, as are the results of observational studies of tumor necrosis factor-alpha inhibitors. Summary Although there is better understanding of the frequency of syndesmophyte development, the pathogenesis of syndesmophytes remains unclear.