Enthesitis in Psoriatic Arthritis, the Sonographic Perspective.

Last-generation US equipment has demonstrated the ability to detect subtle morphostructural and vascular abnormalities at entheseal level. US is able to identify pathologic changes in both "classical" (i.e., the site of attachment of tendons, ligaments, and joint capsules into the bone) and "functional" entheses (i.e., anatomical regions where tendons or ligaments wrap around bony pulleys). US has the potential to be the first-line method in the assessment of enthesitis. In the present review we critically discussed the current definitions of US enthesitis, the scoring systems, and the main fields of application (i.e., the detection of enthesitis in PsA and psoriasis, the identification of different disease subsets, and the assessment of response to treatment).