The stabilizing effect of synovectomy on the synovial membrane in arthritic rabbit knees.

An inflammatory arthritis was induced in rabbit knees by intra-articular injection of human IgG complex in immunized animals. A increased invasion of large plasma proteins into the arthritic knee could be measured by electrophoretic separation of synovial extract and autoradiographic detection of 125I-labeled proteins. Synovectomy resulted in a reduced invasion of plasma proteins compared with the preoperatively arthritic knees. This protective effect was lost, however, following repeated intra-articular IgG injections. Fibrosis and decreased vascularization of the synovectomized knee, the excision of inflammatory cells, and mediators of inflammation are discussed as possible explanations.