Polychrome sequential labeling of subchondrial bone tissue in early and advanced stages of gonarthrosis in male STR/IN-mice

Abstract

Polychrome sequential labeling is used to study the dynamic of subchondral bone sclerosing during developing osteoarthrotic cartilage lesions in knee joints of male STR/1N-mice. The applied technique gives detailed information about site and time of new bone formation in the subchondral tissue using four different colored vital markers. Whereas control animals show regular bone deposition with a circumferential, concentric arrangement of fluorochromes along the various trabeculae, STR/1N-mice with osteoarthrotic cartilage lesions displayed fluorescence bands arranged eccentrically around the marrow cavities always pointing towards the cartilage lesions. The results also demonstrate, that the linear separation between the first label and the anatomic surface of the bone marrow cavity varies considerably in the individual experimental groups. Compared to control knee joints, which show appositional bone growth rates of 25 to 50 microns per 70 days, osteoarthrotic mice reveal increased bone growth rates during developing osteoarthrosis. In early osteoarthrotic cartilage lesions distances between the individual bands are distinctly larger in comparison to distances in advanced lesions. In both cases the rate of appositional bone growth exceeds bone formation in control animals 3 to 4 times.