Purpose of review: This review encompasses a detailed history of spondyloarthritis (SpA) evolution as early as the 17th century, continues on to the current concept of SpA, and ends with current gaps in our understandings of SpA.
Recent findings: Until the early 1960s, ankylosing spondylitis and other SpA family members were considered to be variants of rheumatoid arthritis (RA). The formal medical community separated them from RA at that time, and shortly thereafter they were recognized to be inter-connected based on shared clinical, laboratory, and imaging features. The last two decades have witnessed the formal distinction between axial and peripheral SpA and the connections that exist between nonradiographic and radiographic axial SpA. Recent studies have revealed different microbial compositions among patients with SpA and healthy controls and also between HLA-B27 positive and negative healthy individuals.
Summary: Further investigation of the roles of intestinal microbiome and physical force transduction toward SpA pathogenesis, strategies to improve delay in SpA diagnosis, biomarkers to better predict radiographic progression, and modification of current classification criteria to better address the axial and peripheral groups are gaps in our understandings that pose top priorities for SpA research.