Early diagnosis of temporomandibular joint involvement in juvenile idiopathic arthritis: a pilot study comparing clinical examination and ultrasound to magnetic resonance imaging

Abstract

Objectives: To study the validity of both rheumatological and orthodontic examinations and ultrasound (US) as screening methods for early diagnosis of TMJ arthritis against the gold standard MRI.

Methods: Thirty consecutive juvenile idiopathic arthritis (JIA) patients were included in this pilot study. Rheumatological and orthodontic examinations as well as US were performed within 1 month of the MRI in a blinded fashion. Joint effusion and/or increased contrast enhancement of synovium or bone were considered signs of active arthritis on MRI.

Results: A total of 19/30 (63%) patients and 33/60 (55%) joints had signs of TMJ involvement on MRI. This was associated with condylar deformity in 9/19 (47%) patients and 15/33 (45%) joints. Rheumatological, orthodontic and US examinations correctly diagnosed 11 (58%), 9 (47%) and 6 (33%) patients, respectively, with active TMJ arthritis, but misdiagnosed 8 (42%), 10 (53%) and 12 (67%) patients, respectively, as having no signs of inflammation. The best predictor for active arthritis on MRI was a reduced maximum mouth opening.

Conclusion: None of the methods tested was able to reliably predict the presence or absence of MRI-proven inflammation in the TMJ in our cohort of JIA patients. US was the least useful of all methods tested to exclude active TMJ arthritis.

Fig. 1.

The results of the different examination methods for each patient: each patient is represented by an individual number in a square (patients with condylar deformity on MRI) or a circle (patients without condylar deformities on MRI). The red colour stands for pathological findings on MRI. The blue, green and pink colours depict pathological findings in the rheumatological, orthodontic and US examinations, respectively.

Fig. 2.

The orthodontic maximum mouth opening (y-axis) is shown for the three different categories of MRI contrast enhancement of the synovium (x-axis). Each dot represents the measurement result for one patient. The diamond depicts the mean value and the quartiles. The grey horizontal line depicts the mean maximum mouth opening of the total cohort. The difference between the three groups is statistically significant with P = 0.01 (one-way ANOVA).