Does joint effusion on T2 magnetic resonance images reflect synovitis? Part 3. Comparison of histologic findings of arthroscopically obtained synovium in internal derangements of the temporomandibular joint.

OBJECTIVES: To evaluate the relationship between the volume of joint effusion (JE), determined by T2-weighted magnetic resonance imaging (MRI), and microscopic findings of synovial inflammation in internal derangement of the temporomandibular joint (TMJ). STUDY
DESIGN: Magnetic resonance images of 53 symptomatic TMJs (53 patients) associated with painful hypomobility were taken to evaluate the degree of JE on a scale of 0 to 3. Within 2 months after MRI, biopsy specimens obtained by arthroscopy were quantitatively assessed, on the basis of Gynther's grading system, for severity of hyperplasia of synovial lining cell layers, vascularity, and the presence of inflammatory cells. Each synovitis score was compared among the 4 JE grades, as well as between 2 groups-effusion present (grades 2 and 3) and effusion absent (grades 0 and 1)-by using the Spearman correlation coefficiency and the Mann-Whitney U test.
RESULTS: The distribution of JE was as follows: 14 joints had grade 0, 9 joints had grade 1, 19 joints had grade 2, and 11 joints had grade 3. Significant relationships were found between the grades of JE and scores of synovial lining cell layers (P =.0012) as well as between the grades of JE and scores of presence of inflammatory cells (P =.0064). The joints with effusion had significantly higher scores for synovial lining cell layers (2.0 +/- 0.2) than the joints without effusion (1.3 +/- 0.2) (P =.029). There was no statistically significant correlation between the scores of vascularity and JE (P =.394).
CONCLUSIONS: The evidence of JE on MRI might correlate with synovial inflammatory activity. It confirms the common consensus that JE probably reflects synovitis, especially when synovial hyperplasia has a key role in the pathogenesis of JE.