POS1307 ULTRASOUND-DETECTED TENOSYNOVITIS IN ANKLES WITH CLINICALLY ACTIVE DISEASE OF CHILDREN WITH NEW-ONSET JUVENILE IDIOPATHIC ARTHRITIS DOES NOT AFFECT THE CHANCE TO ACHIEVE DISEASE REMISSION
Authors: S. Lanni, O. De Lucia, S. Orsi, S. Costi, G. Beretta, T. Giani, G. Filocamo, C. V. Agostoni, R. Cimaz
Journal: Annals of the Rheumatic Diseases (2021)

Background: The ankle is one of the most commonly affected sites in juvenile idiopathic arthritis (JIA). This region has a complex anatomical structure owing to the presence of multiple joint recesses and surrounding tendons. While the prognostic value of ultrasound (US)-detected arthritis has been investigated in recent studies, the role of tenosynovitis in JIA remains still unexplored. Objectives: To investigate: 1) US features of ankle involvement in JIA at disease onset; 2) the predictive value of US-detected tenosynovitis in ankles with clinically active disease of children with new-onset JIA. Methods: The clinical charts of all consecutive patients with new-onset JIA between May 2018 and January 2020 at study centres (Policlinico and G.Pini Hospitals of Milan) and with clinically active ankle disease among the joints affected were reviewed retrospectively. Data on ankle US assessment were retrieved and patients were then stratified as follows: 1) patients with detection on US of isolated arthritis in at least one of the joint recesses of the ankle region; 2) patients with detection on US of tenosynovitis in at least one of the tendon compartments of the ankle irrespective of the presence of concomitant arthritis. For each of these two categories, estimation of patients who were able to achieve clinical disease remission at 12 months since disease onset was evaluated. Results: Twenty-seven new-onset JIA patients were found to have clinical involvement of the ankle among the joints affected. Nine of them (33.3%) showed on US isolated arthritis of the ankle, whereas US-detected tenosynovitis was found in 18 (66.7%) patients. The amount of patients who were able to achieve disease remission at 12-months was the same (66.7%) for both patients with and without US-detected tenosynovitis in the ankle (12/18 and 6/9 patients, respectively). In patients with US-detected tenosynovitis and clinical disease remission at 12 months, the lateral tendon compartment (LTC) was the tendon site more frequently affected by pathology (75.0%). Patients with US-detected tenosynovitis that did not achieve clinical disease remission at follow-up had the highest frequency of tendon pathology on US in the medial tendon compartment (MTC) (83.3%). The anterior tendon compartment was the less frequently affected tendon compartment of the ankle in all patients (33.3% in both patients with and without clinical remission of disease at the 12-months follow-up visit). Conclusion: US-detected tenosynovitis of the ankle is a common finding in patients with new-onset JIA with clinically ankle disease activity and is more frequent than the detection on US of isolated arthritis. The MTC and LTC are the tendon compartments more commonly affected on US. The detection on US of tenosynovitis at disease onset in ankles with clinical disease activity did not seem to affect the change to achieve the overall clinical disease remission compared to patients without tendon pathology but with joint disease in the ankle region. Disclosure of Interests: None declared