Juvenile idiopathic arthritis (JIA) is the most common childhood chronic rheumatic disease, encompassing all forms of arthritis that persist for more than 6 weeks, with onset before age 16, after exclusion of other causes of arthritis. It is a heterogeneous disease, whose complexity is only partially encompassed by the actual classification criteria and it is characterized by prolonged synovial inflammation that can lead to joint destruction.

Whilst the assessment of structural joint damage is part of the routinary evaluation of disease severity and progression in patients with rheumatoid arthritis (RA), to the extent that it is considered a key end-point outcome in treatment efficacy studies, this is not the same for JIA. Some recommendations have been elaborated based on expert opinion, but only recently they have been translated into clinical practice. Such a discrepancy in approaching chronic arthritis has been for many years due to the lack of articular damage radiographic scoring system validated for pediatric age. Actually, joint space narrowing, bone erosions and demineralization, which is typical of adult articular damage, are not the same changes observed in pediatric population where early growth plate closure, epiphyseal deformity and growth asymmetries can be the major signs.

The transition process from the pediatric to the adult health care team is a critical moment in the clinical history of patients with JIA, often hampered by the absence of specific criteria for the assessment of disease activity, the lack of specific treatment recommendations for JIA adult patients, the poor adolescent-specific training for adult rheumatologists, and the lack of communication between pediatric and adult centers. Adult patients with JIA have their own specific identity and should not be inappropriately re-categorized as having RA, ankylosing spondylitis or another condition once transitioned to the adult rheumatologist.

The aim of this study is to quantify the articular damage of adult patient with JIA after closure of growth plates. This represent a sort of starting burden carried by the patients who receive transition to the adult rheumatologist care and which should be minimized in order to reduce long-term complications. Furthermore, the study aims to analyze possible correlations between the presence of articular damage, therapies taken in pediatric age, and characteristics of JIA at the onset and during the clinical course of the disease

Inclusion Criteria:

1. Patients aged between 16 to 25 years who received a diagnosis of JIA in pediatric age according to International League of Associations for Rheumatology criteria (2001) and who have begun the process of transition to adult care.
2. Young adults undergoing healthcare transition process from the the pediatric to adult rheumatology since 2016.
3. Patients with radiological evidence of joint plates closure.
4. X-ray images of hands, hips, and knees available

Exclusion Criteria:

1. Patients cared at the adult rheumatology clinic who received a diagnosis of arthritis in the adult age.
2. Patients with other orthopedic conditions or affected by other diseases leading to osteoporosis or skeletal deformities.
3. Patients affected by other rheumatological conditions who underwent healthcare transition process from the the pediatric to adult rheumatology center.

All patients with Juvenile Idiopathic Arthritis who started transition process from a pediatric to an adult rheumatology center in the last 10 years will be enrolled