Morpho-structural alterations of sub-chondral bone tissue in patients with osteoarthritis: a scanning electron microscopy study

Abstract

Osteoarthritis focuses principally on the degeneration of articular cartilage as a primary cause of the disease. The pathophysiological process of osteoarthritis is characterized by alteration of chondrocytes and the increased bone formation by sub-chondral osteoblasts. Infiltration of macrophages and perivascular T and B lymphocytes is observed, and these infiltrates have been demonstrated in both early and advanced disease. The morphological and phenotypic characteristics of osteocytic cells attached to the normal and the osteoarthritic matrix differ from each other, suggesting that specific signalling pathways arise or are altered between matrix and cells. On this basis, we have examined biopsies of bone obtained by normal femur and by femur of subjects affected by osteoarthritis using techniques of scanning electron microscopy in order to identify the morphostructural alterations that occur in the sub-chondral bone. Our results have shown that the bone tissue of subjects not affected by any disease of bone presents a well-organized structure, while the bone tissue obtained by patients affected by osteoarthritis shows a derangement of tissue itself possibly correlated with altered function of the osteoblasts, that during the pathological process produce a less mineralized extracellular matrix with consequent loss of the normal bone structure. In our opinion, during the osteoarthritic process there would be a defective signalling between bone cells leading to the production of an irregular, amorphous extracellular matrix by osteoblasts, characteristic of the pathological condition.