Synovitis in internal derangement of the temporomandibular joint: correlation between arthroscopic and histologic findings

PURPOSE: To define arthroscopic criteria for synovitis (SYN) reflecting specific histologic changes. Arthroscopic observations in the temporomandibular joint of patients with internal derangement were compared with histologic patterns in synovial biopsies obtained during arthroscopy. PATIENTS AND METHODS: Arthroscopic biopsies were obtained in 31 joints of 31 patients using an oriented semiblind technique. The histologic changes in the biopsies were compared with those in age-matched reference material obtained at autopsy. RESULTS: Microscopic examination of the reference material showed inflammation in three specimens (18%), whereas it showed inflammation in 22 patient specimens (71%). Biopsies from the patients also exhibited more pronounced inflammation. According to conventional criteria, arthroscopy showed mild SYN (increased vascularity) in 51%, moderate changes in 39%, and more pronounced changes in 10% of the joints. The presence of moderate or pronounced arthroscopic signs of SYN (capillary hyperemia and synovial hyperplasia), correlated well with the histologic diagnosis of SYN. This was in contrast to patients with mild arthroscopic SYN (increased vascularity). CONCLUSION: Increased vascularity seen during arthroscopy must be questioned as a sign of SYN. More reliable criteria seem to be capillary hyperemia and synovial hyperplasia.