Review of the use of ultrasound for the diagnosis and monitoring of enthesitis in psoriatic arthritis.

Musculoskeletal ultrasound is rapidly advancing, with contemporary machines offering exquisite high-resolution pictures of superficial structures such as tendons, ligaments, bursae, and joints. It is a useful tool that maybe used to evaluate patients with psoriasis and psoriatic arthritis. High-resolution transducers readily depict ultrastructural changes in the entheses and surrounding structures, while Doppler modalities elicit signs of increased blood flow, suggesting inflammation. Some of the findings seen at the entheses of psoriatic patients maybe viewed in an alternative framework of an enthesis organ concept. There are limited studies that search for the presence of enthesopathy in patients with psoriatic arthritis. Most of these examine lower extremity entheses with heterogeneous scoring methods. Similar indices have been used to examine patients with psoriasis to elucidate signs of early or occult psoriatic enthesitis. Although ultrastructural differences have been noted compared with control groups, longitudinal data are lacking with regard to placing these changes in the context of future development of psoriatic arthritis or functional outcome.