Abstract

Fibronectin is a minor component of cartilage connective tissue matrix, which is reported to accumulate in increased amounts in osteoarthritis. The presence of raised levels of fibronectin in human osteoarthritic cartilage by immunoperoxidase localisation is confirmed. Residual femoral head articular cartilage from 17 patients with osteoarthritis contained variable but substantial amounts of fibronectin. This was localised mainly in a band within the matrix of the surface zone. No significant deposits of fibronectin were found in this or any other area of the normal specimens. Intracellular fibronectin was identified in some cells of the surface zone, indicating that it was, in part, synthesised locally. The presence and distribution of locally produced fibronectin in osteoarthritic cartilage suggest that its synthesis is a response by chondrocytes to changes in the cartilage matrix.