Advances in the Diagnosis and Treatment of Enthesitis-Related Arthritis

Abstract

Enthesitis-related arthritis (ERA) represents 5-30% of all cases of juvenile idiopathic arthritis (JIA) and belongs to the spectrum of the disorders included in the group of juvenile spondyloarthritis. In the last decade, there have been considerable advances in the classification, diagnosis, monitoring, and treatment of ERA. New provisional criteria for ERA have been recently proposed by the Paediatric Rheumatology INternational Trials Organisation, as part of a wider revision of the International League of Associations for Rheumatology criteria for JIA. The increased use of magnetic resonance imaging has shown that a high proportion of patients with ERA present a subclinical axial disease. Diverse instruments can be used to assess the disease activity of ERA. The therapeutic recommendations for ERA are comparable to those applied to other non-systemic JIA categories, unless axial disease and/or enthesitis are present. In such cases, the early use of a TNF-alpha inhibitor is recommended. Novel treatment agents are promising, including IL-17/IL-23 or JAK/STAT pathways blockers.

Keywords: childhood arthritis; enthesitis-related arthritis; juvenile idiopathic arthritis; juvenile spondyloarthritis; pediatric rheumatology; sacroiliitis.

Figure 1

Modified Schober’s test [52]. With the patient standing upright, a line connecting the dimples of Venus is drawn as a landmark for the lumbosacral junction (A). Then, marks are placed midline 5 cm below (point 1) and 10 cm above lumbosacral joint (point 2). With the subject bent forward in maximum lumbar flexion with the knees straight, the distance between point 1 and point 2 is measured as an indicator of the lumbosacral spine mobility (B). An increase less than 6 cm indicates lumbosacral spine dysmotility [41,52].

Figure 2

Entheses commonly explored by pediatric rheumatologists [15,41,57,60,61]. Figure modified with markings (circles) after adaptation of “Skeleton” from Servier Medical Art by Servier, licensed under a Creative Commons Attribution 3.0 Unported License.

Figure 3

Ultrasound findings in enthesitis. Longitudinal scans of Achilles tendon and enthesis in Gray scale (A) and Power Doppler (B) show increased thickness, impairment of fibrillar pattern and hypoechoic areas (star) with active Doppler signal (B) within 2 mm from the bony cortex. Retrocalcaneal bursitis (asterisk) and enthesophyte (step up of the bony prominence at the end of the normal bone contour, arrow) as well as irregular contour of the calcaneal bone can also be seen as associated findings.