Temporo-mandibular joint alterations in juvenile idiopathic arthritis and young-onset inflammatory arthropathies: a magnetic resonance imaging study with ultrasound comparison

BACKGROUND: To assess temporomandibular joint (TMJ) alterations using magnetic resonance imaging (MRI) in pediatric and young adult patients with juvenile idiopathic arthritis (JIA) and non-JIA inflammatory arthropathies, and to evaluate the added value of ultrasound (US). METHODS: The study prospectively included three groups of patients: children with JIA; young adults under 35 years with JIA, and young adults under 35 years with non-JIA inflammatory arthropathies. All patients underwent joint count assessment, clinical examination of the TMJs, evaluation of global disease activity and TMJ MRI to identify inflammation or structural damage. TMJ US was additionally performed in the two young adult patient groups. Associations between clinical findings and MRI results were then analyzed using appropriate group comparison tests. Concordance between MRI and US findings was also calculated. RESULTS: A total of 41 patients were enrolled: 14 in the pediatric JIA group, 19 in the adult JIA group, and 8 in the adult non-JIA group. MRI analysis revealed significantly greater joint damage in adults compared to pediatric patients (p = 0.05). Tenderness on physical examination was significantly associated with MRI-detected joint damage (p = 0.01), whereas retrognathia was associated with MRI evidence of inflammation (p = 0.02) in all patients. The negative predictive value of clinical examination for detecting TMJ alterations was low (47.8%). US, performed in 18 out of the 27 adults, was compared with MRI findings and demonstrate poor concordance, with a sensitivity of 48% (95%CI 0.28-0.68), and a specificity of 73% (95%CI 0.47-0.99). CONCLUSIONS: TMJs alterations were common across all three patient groups. Clinical examination showed limited association with MRI-detected morphological lesions. MRI remains the gold standard for TMJ assessment, while the diagnostic performance of US requires optimization to enhance both sensitivity and specificity. TRAIL REGISTRATION: "Comité Local d'Ethique Recherche (IRB) du CHU de Montpellier" no. IRB-MTP_2022_06_202201149.