Spondyloarthritis (SpA) is an umbrella term for a group of rheumatic diseases 
characterised by inflammation of the sacroiliac (SI) joints and vertebral 
column; today, differentiation is made between axial SpA and peripheral SpA. 
Ankylosing spondylitis (Bechterew's disease) is the most typical form of axial 
SpA whereby sacroiliitis can be found on X-rays of the SI joints. Axial SpA can, 
however, also be present without radiographic evidence of sacroiliitis. A range 
of SpA-related symptoms can also manifest themselves outside the musculoskeletal 
system, for example, uveitis, psoriasis and inflammatory intestinal diseases. 
Tumour necrosis factor (TNF)-α inhibitors play an important role in the 
treatment of SpA. New classification criteria have recently been established in 
which MRI of the SI joints and the presence of the HLA-B27 tissue antigen are 
key. Axial and peripheral SpA should be recognized early in order to be able to 
successfully treat these conditions.