Musculoskeletal Ultrasound for Diagnosis and Treatment in Juvenile Idiopathic Arthritis

Among users of musculoskeletal ultrasound (MSUS), the benefits of real-time imaging of patients with juvenile idiopathic arthritis (JIA) are widely appreciated. Yet to the larger pediatric rheumatology public, these advantages may be easily overlooked. MSUS enhances the routine clinical examination, allowing for detection of subclinical disease and an accurate determination of the location and extent of disease activity. Ultrasound visualizes synovitis and tenosynovitis, enthesitis, erosions, and cartilage changes, enabling one to monitor the response to treatment and assisting in the determination of remission. MSUS is particularly suited for guidance for intraarticular corticosteroid injections. The ability to review images at the bedside with patients and their caregivers can be reassuring, to both the patient and the practitioner. Understanding of the normal, healthy sonoanatomy, however, can be challenging and remains a topic of ongoing research. The significance of subclinical synovitis (US-detected features of synovitis in the context of clinically healthy joint) remains unclear. As a better understanding of normal/physiologic sonographic appearance of the growing joint emerges, in particular, the presence of Doppler signal in the developing articular space, the predictive value and prognostic significance of subclinical synovitis will become more evident. What constitutes subclinical disease, too, is somewhat controversial as many healthy joints can demonstrate physiologic fluid, and it is unknown how long synovial thickening can remain after active inflammation has been treated. In my experience, sonographic evidence of synovial thickening/proliferation with a high degree of Doppler activity (more than a few areas of intermittent pixilations) should be considered an actively diseased joint and be incorporated in therapeutic decisions. This review aims to provide an evidence-based update on recent advances and insights into the healthy sonoanatomy of children and the use of ultrasound in the assessment and treatment of juvenile idiopathic arthritis disease manifestations.