Microangiographic studies of experimental erosive synovitis in rats

Chronic remittent erosive synovitis, which is clinically, radiologically and pathologically similar to rheumatoid arthritis in man, can be produced in rats by systemic injection of cell wall fragments isolated from Group A streptococci. Because of our desire to study the synovial microvasculature in this experimental model, we developed a reliable microangiographic technique to document these changes. This paper describes the first reported microangiographic studies of rat joints and discusses the microvascular changes that parallel the previously reported radiographic and histologic findings. As the arthritis progresses, as judged by clinical and radiographic parameters, early synovial hypervascularity associated with developing hyperplastic synovium gives way to a more obliterative hypovascular pattern associated with chronic erosions, periosteal reaction, and fibrous ankylosis. Microangiography offers an additional and helpful modality by which to investigate synovial microvascular morphology as well as the pathophysiology of joint destruction during erosive synovitis.