Purpose or Case Report: Temporomandibular joint (TMJ) arthritis is a common yet often overlooked manifestation of juvenile idiopathic arthritis (JIA), affecting up to 40% of patients. Magnetic resonance imaging (MRI) is regarded as the gold standard for identifying early inflammatory abnormalities and structural damage. Despite widespread recognition of TMJ involvement in JIA, the prevalence and clinical significance of asymptomatic disease remain incompletely understood. We aimed to determine the frequency and imaging characteristics of TMJ involvement, including asymptomatic cases, in a 10-year cohort of children and adolescents with JIA.
Methods & Materials: We performed a 10-year retrospective cohort study of pediatric patients with JIA who underwent TMJ MRI at a tertiary children's hospital from 2014 to 2024. Clinical parameters included demographics, JIA subtype, symptoms, and comorbidities. MRI scans were independently evaluated by two radiologists using the Juvenile Idiopathic Arthritis MRI Scoring System for the TMJ (JAMRIS-TMJ), focusing on inflammatory features (synovitis, joint effusion, bone marrow edema) and structural damage (condylar flattening, erosions, disc abnormalities).
Results: Of 165 patients with JIA, 35 (21%) demonstrated TMJ involvement on MRI. The population was primarily female (83%), with a median age at MRI of 13 years (range, 4–21) and a median disease duration of 2 years. Polyarticular JIA was the most prevalent subtype (54%). Clinical symptoms were present in 91% of patients, most commonly TMJ pain (77%), dentofacial abnormalities (26%), and restricted mouth opening (20%); 9% were asymptomatic. MRI findings included condylar flattening in 80%, erosions in 66%, synovitis in 60%, bone marrow edema in 51%, and joint effusion in 40%. Disc displacement was seen in 29% of cases. Pain showed no significant correlation with the damage domain (p=0.41) or the inflammatory domain (p=1.00). Notably, MRI abnormalities were detected in 2 of 3 (67%) asymptomatic patients.
Conclusions: TMJ involvement in JIA is prevalent and frequently asymptomatic. Pain is not a reliable indicator of MRI-confirmed disease, underscoring the importance of regular MRI monitoring to detect early inflammation and prevent long-term orofacial complications.