Does joint effusion on T2 magnetic resonance images reflect synovitis? Comparison of arthroscopic findings in internal derangements of the temporomandibular joint

Objective. The purpose of this study was to clarify the characteristics of joint effusion (JE) in the temporomandibular joint by comparing T2-weighted magnetic resonance (MR) images with arthroscopic findings. Study design. MR images of 47 symptomatic temporomandibular joints (47 pati ents) with internal derangement associated with painful hypomobility were t aken to evaluate the degree of JE on a scale of 0 to 3. Within 2 months aft er MR images, arthroscopic findings with respect to the severity of synovit is, adhesion, and degenerative change in the superior compartment were each quantitatively assessed on a scale of 0 to 10. The arthroscopic scores wer e compared among the 4 JE grades, as well as between 2 groups, effusion-pre sent (grades 2 and 3) and effusion-absent (grades 0 and 1), by using the Sp earman correlation coefficient and the Mann-Whitney U test. Results. The distribution of JE was as follows 10 joints had grade 0, 5 joi nts had grade I, 19 joints had grade 2, and 13 joints had grade 3. The syno vitis score had a significant relationship to the degree of effusion (P = . 0012) and was higher in the effusion-present group (6.4 +/- 2.0) than in th e effusion-absent group (4.2 +/- 1.6) (P = .0005) on the other hand, there was no statistically significant correlation between either adhesion or deg enerative change and effusion. Conclusions. JE may reflect synovitis; however, the nature of JE itself nee ds to be further elucidated by additional studies.