Temporomandibular joint involvement in juvenile idiopathic arthritis: clinical predictors of magnetic resonance imaging signs.

The aim of the study was to define clinical predictors of magnetic resonance imaging (MRI) findings of temporomandibular joint (TMJ) involvement in juvenile idiopathic arthritis (JIA). Forty-six patients, aged 2.08-36.7 years, with JIA (oligoartitular 18, polyarticular 17, systemic type 11) were examined with standard plain and contrast-enhanced sequences. Of 88 TMJs examined, an abnormal condyle was observed in 32%, flattened articular eminence in 27%, flattened articular disk in 17%, intra-articular fluid in 10%, enhancing pannus in 45% and restricted condylar motion in 9%. Logistic regression analysis revealed that for abnormal condyle and flattened articular eminence, independent predictors were type of JIA (P < 0.015), age at onset (P < 0.038), and duration of disease activity (P < 0.001). Plots of the logistic regression models showed that TMJ involvement approached certainty for systemic sooner than for the other JIA types. Pannus was present with probability >0.5 when the disease started before 4 years of age. In conclusion, the systemic type of JIA, young age at onset and long duration of activity are risk factors for TMJ damage. MRI of the TMJ should be performed in patients who are less than 4 years of age at the onset of JIA, and in those with the systemic type, whatever the age of onset.