Traumatic synovitis analysed by arthroscopy and immunohistopathology.

The synovitis induced in previously healthy subjects by knee joint trauma was investigated at arthroscopic surgery performed after 3-70 days. Synovitis was confined to the areas of the synovial membrane bordering the cartilage lesion and displayed a varied intensity of inflammation. Biopsies were sampled under direct vision from the area of the peak inflammatory intensity within each joint and analysed by immunohistopathology. Only sparse lymphocytic infiltration and a slight increase of lining cell layers were found in the biopsies after as long as 70 days. The restricted extent and limited intensity of the inflammatory changes contrast with previous findings in rheumatoid arthritis. However, the arthroscopic and immunohistopathological signs of synovitis were no different.