Abstract
Sacroiliitis, inflammation of the sacroiliac joint (SIJ), may be associated with many rheumatic and nonrheumatic disorders. The diagnosis of sacroiliitis may be difficult in many patients, and awareness of its typical manifestations along with recognition of its diverse presentations and cognizance of the limitations of today's imaging modalities are critical to good clinical practice. This review presents the didactic approach to the early diagnosis of sacroiliitis in patients with suspected axial spondyloarthritis and other nosologic entities, discussing also differential interpretation of information acquired from patients' histories, physical examination, and imaging.