The role of ultrasound in the diagnosis and management of psoriatic arthritis.

Psoriatic arthritis (PsA) presents many diagnostic, management and research challenges for rheumatologists who wish to obtain early diagnosis, differentiate synovitis and enthesitis, monitor disease activity accurately and objectively, prevent the development of structural damage, deliver local therapy accurately, and obtain PsA tissue for research purposes. Musculoskeletal ultrasound (MSUS) is widely used by European rheumatologists in their clinical practice to meet these challenges and has the potential to become the rheumatologist's stethoscope in Europe and North America. This paper examines the evidence that MSUS can improve clinical evaluation of patients with PsA for synovitis and enthesitis, that MSUS is more sensitive than plain radiography in detecting structural damage in joints, that MSUS can improve the success of joint aspiration and guide biopsy of PsA tissues. Recent exciting developments in the management of PsA are detailed including the role of power Doppler in the diagnosis of enthesitis in PsA, the role of MSUS in objective monitoring of disease activity, the evaluation of MSUS in the diagnosis of sacroiliitis, and the use of MSUS to guide therapeutic injection of the sacroiliac joints.