Abstract

Axial spondyloarthritis (axSpA) is a chronic inflammatory rheumatic disease that manifests primarily in the axial skeleton, initially mostly in the sacroiliac joints (SIJ), usually later spreading to the spine. The disease is characterised by inflammation and new bone formation which are mainly assessed by conventional radiography (CR) and magnetic resonance imaging (MRI). Tumour necrosis factor inhibitors (TNFi) and interleukin-17 antagonists have been shown to be efficacious and efficient in patients with axSpA. This treatment seems to also inhibit structural damage, for example, retard radiographic progression. Indeed, a reduction of new bone formation in the spine, as assessed by CR, has been reported to occur after at least 2 years of therapy with TNFi. Recently, a reduction of erosions and ankylosis in the SIJ has also been observed in axSpA patients treated with etanercept and filgotinib. In this narrative review, we discuss the limited significance of such findings.