Purpose: This study was conducted to measure the intra-articular levels of prostaglandin E2 (PGE2), hyaluronic acid, and chondroitin-4 and -6 sulfate in patients with temporomandibular joint (TMJ) internal derangement involving a closed lock, and to see if these levels correlate with the clinical or arthroscopic findings.
Patients and methods: Fifteen female patients (16 joints) with a mean age of 36.7 years were diagnosed as having a closed lock by clinical examination and diagnostic MR imaging. The patient's subjective pain was assessed by a visual analog scale (VAS) and a pain questionnaire (pain score), and the interincisal opening was measured. TMJ aspirates were obtained by washing of the joint with saline containing vitamin B12 as a marker for calibration of data. The samples were assayed for PGE2 with a radioimmunoassay, and the concentrations of unsaturated disaccaride isomers of hyaluronic acid (delta di-HA), chondroitin-4 sulfate (delta di-4S), and chondroitin-6 sulfate (delta di-6S) were measured by high-performance liquid chromatography. Immediately after collection of the synovial aspirates, diagnostic arthroscopy was performed on all but three joints to evaluate the severity of synovitis and cartilage degeneration. The degree of arthroscopic pathology was scored quantitatively. Intra-articular levels of PGE2, delta di-HA(HA), delta di-4S(C4S), and delta di-6S(C6S) were compared with patient's age, mouth opening, VAS rating, pain scores, and arthroscopic scores for synovitis and cartilage degeneration.
Results: The PGE2 level did not correlate with the clinical or arthroscopic parameters. HA had a weak correlation with mouth opening (0.54). C4S and C6S were correlated with arthroscopic scores of TMJ degeneration (0.97, 0.89) and with age (0.75, 0.62). The ratio of C4S and C6S to HA was also correlated with the arthroscopic indices of degeneration (0.93, 0.8) and PGE2 level (0.74, 0.69), but not with age.
Conclusion: The PGE2 level in the TMJ synovial fluid does not specifically reflect the intensity of pain or synovitis, but the detection of high concentrations of C4S and C6S, compared with the amount of HA, is a possible marker of proteoglycan degradation in the TMJ.