To better define the role of synovium in the pathogenesis of osteoarthritis (OA).
We measured the bioactivity of tumor necrosis factor-alpha(TNF-alpha) in synovial fluid (SF) and examined the histologic and ultrastructural features of the synovium from patients with OA and from patients with acute and chronic traumatologic joint.
The results showed that the levels of TNF-alpha in SF from OA were significantly elevated. Marked fibrosis and thickened intima were found in OA synovium, with much dense collagen, which, in some cases, was banded, but no specific inflammatory changes were detected. Type B cells in OA synovium had the characteristics of organelles of cells active in synthesizing and secreting protein. Type A cells in OA synovium had the features of the macrophage.
Evident fibrosis in synovium may be either mediated by the cartilage degradation product or by the enhanced joint damage process in OA.