An ultrasound protocol for temporomandibular joint in juvenile idiopathic arthritis: a pilot study

Objectives: As it is well known, the diagnosis of temporomandibular joint (TMJ) involvement in patients affected by Juvenile Idiopathic Arthritis (JIA) is important to avoid the impairment of mandibular growth. In this context, Magnetic Resonance Imaging (MRI) is the gold-standard for detection of TMJ involvement, however it is expensive and requires patients' collaboration. The aim of this study was to evaluate if ultrasound may be used as an alternative tool to investigate the acute signs of TMJ involvement in JIA patients. Methods: Lateral periarticular space (LPAS) and joint effusion were evaluated by ultrasound in a study Group A of 8 JIA children (11.6 +/- 3.5 years old) with 14 TMJs involved, as confirmed by MRI, and in a control Group B of 7 healthy children (9.3 +/- 1.2 years old) without temporomandibular disorders (TMD). The LPAS width values were compared between the two groups using the Mann-Whitney test. The ultrasound images of the JIA group were then matched with the corresponding MR images; the Spearman Rank Correlation test and the Bland-Altman test were used to evaluate the differences. Results: The LPAS values in Group A were statistically significantly higher than those in Group B (p < 0.001). There was no overlap of the LPAS values confidence intervals (CIs) between the two groups. No signs of joint effusion were identified in groups A and B. The Spearman test applied to the values of LPAS measured in ultrasound and the corresponding MR images showed a proportional positive correlation with a p of 0.623 and a p < 0.05. Conclusions: Ultrasound can detect differences in the TMJ features between JIA patients and healthy patients and it might be used as a follow-up tool in the assessment of TMJ involvement in subject affected by JIA.