Ultrasound of enthesopathy in rheumatic diseases

Enthesopathy is the pathologic change of the insertion of tendons, ligaments and joint capsules on the bone. It is a cardinal feature of spondyloarthropathies (SpA), but it can occur in other rheumatic disease. Recent studies using magnetic resonance imaging (MRI) and ultrasonography (US) have demonstrated that enthesopathy can often be asymptomatic, in both the axial and peripheral skeleton. Therefore, a systematic US study of peripheral entheses could be useful in the diagnostic process of patients with rheumatic diseases, in particular SpA. Recently, power Doppler US (PDUS) has been proved to be useful for differentiating mechanical/degenerative and inflammatory enthesopathy and for monitoring the efficacy of therapy. This article reviews the main histopathologic aspects of enthesopathy and describes the normal US features of enthesis and the basic US features of enthesopathy, in its various stages. The usefulness of US and PDUS in the diagnosis and assessment of enthesopathy is discussed on the basis of the literature and our experience.