Purpose: This study investigated the early signs of synovitis and cartilage degradation by means of synovial fluid analysis in temporomandibular joints (TMJs) with internal derangement (closed lock) or osteoarthritis (OA).
Patients and methods: Synovial fluid was obtained from 25 TMJs in 22 patients diagnosed with closed lock and from 15 asymptomatic TMJs of 12 normal controls. IL-1 beta concentrations were measured using enzyme-linked immunosorbent assay (ELISA), and proteinase activity was detected by means of gelatin enzymography.
Results: Nine of the 25 TMJs with closed lock (CL group) exhibited osteolytic changes on the surface of the condyle. TMJs in the normal control group did not show any bony changes. Mean IL-1 beta concentration in the synovial fluid (SF) protein in the CL group was 330.1 +/- 347.7 pg per 100 micrograms protein, which was significantly higher than in the normal control (76.7 +/- 95.3 pg/100 micrograms SF-protein). Synovial fluid from the TMJs with osteolytic changes contained higher levels of IL-1 beta (531.8 +/- 379.6 pg/100 micrograms SF-protein) than those without bony changes (216.7 +/- 280.1 pg/100 micrograms SF-protein). Matrix metalloproteinase (MMP) activity with a molecular weight of 50 kd (stromelysin or MMP3) was detected in a highly augmented form in two synovial fluid samples of seven closed lock patients.
Conclusion: The results suggest that IL-1 beta levels in synovial fluid of the TMJ have a positive correlation with OA change. The MMP3 activity detected was greatly increased in patients with cartilage degradation. These findings suggest that both changes may be important markers of early bone deterioration in TMJs that are undetectable by radiograph imaging.