Proteoglycans in the synovial fluid of the temporomandibular joint as an indicator of changes in cartilage metabolism during primary and secondary osteoarthritis

Purpose: The specific aim of this investigation was to assess differences between primary and secondary osteoarthritis (OA) of the temperomandibular joint (TMJ) using clinical evaluation and synovial fluid analysis for proteoglycans. Materials and Methods: Arthroscopic surgery was performed on 101 TMJs from patients with significant pain or dysfunction and who had failed to respond to treatment, Joints were assessed for primary and secondary osteoarthritis. Synovial fluid aspirates were obtained and analyzed to determine the levels of keratan sulfate (KS) epitope and a novel 3B3(-) epitope by enzyme-linked immunosorbent assay (ELISA). Results: Fifty-four patients and 67 joints had OA diagnosed by both clinical examination and arthroscopy, Primary OA was diagnosed in 14 joints (20%), and the remaining 53 joints were regarded as having secondary OA. No differences were detected in the levels of KS in the synovial fluid from the primary and secondary OA joints. Furthermore, the 3B3(-) epitope was not detectable in the synovial fluid aspirates of any TMJ. Conclusion: Secondary OA is a common disorder of the TMJ. However, there is no apparent difference in the metabolism of the joints with primary and secondary OA as assessed by proteoglycans in the synovial fluid. The apparent absence of the 3b3(-) epitope, in contrast to its presence in OA of other major synovial joints, suggests that there are some differences between the cartilage metabolism of the TMJ and these other joints during OA.