Relationship Between Effusion and TMJ Hard and Soft Tissue Status

Method: This cross-sectional case-control study consisted of the 614 temporomandibular disorders (TMD) cases from the multi-center RDC/TMD Validation Project.  All cases had bilateral TMJ magnetic resonance (MR) imaging and computed tomography (CT). Subjects had a TMD expert-based consensus diagnosis of normal TMJ, disc displacement with reduction (DDwR), DD without reduction (DDw/oR) or degenerative joint disease (DJD). T-2 weighted MR images were used to detect the presence or absence of effusion. A blinded board-certified radiologist interpreted all images. The proportions of cases with effusion in the four categories of hard/soft tissue intraarticular status (Normal, DDwR, DDw/oR, DJD) were evaluated. The differences in proportions were assessed using a chi-squared test.

Result: The proportion of effusion increased from 49% in subjects with normal joints to 65% in subjects with DDwR and remained relatively similar in subjects with DDw/oR (63%) and with DJD (64%). There was no statistically significant difference in proportions across these hard/ and soft tissue intraarticular status categories (P=0.09). There was statistically significantly less effusions in TMD cases with normal joint status compared to all DDwR, DDw/oR, and DJD combined (P=0.01). Findings were reassessed in TMD cases of the RDC/TMD Impact Study.

Conclusion: Effusion is common in TMD cases. The frequency of TMJ effusion increased in TMD cases with DDwR, DDw/oR, and DJD compared to cases with normal joints, but was not different among the latter three TMJ disorders.  Given the significant number of effusions present in all intraarticular categories, this suggests that effusions are poorly related to soft or hard tissue findings.