Vasculature of the normal and arthritic synovial joint.

The vasculature of the normal and arthritic knee is described. The joint contains a number of different tissues, many of which are heterogeneous and each with varying degrees of vascularization. In the normal joint the vasculature is highly organised, some tissues are highly vascular with well defined vascular organisation, whilst other tissues are avascular. During arthritis vascular turnover is increased. This vascular plasticity leads to redistribution of the vascular bed and may compromise its functional ability. The normal joint is able to regulate its blood flow, but this ability may be compromised by the inflammation and increased synovial fluid volume that are associated with joint disease. Growth of the subchondral vasculature into the articular cartilage may also occur, leading to ossification of the articular cartilage.