Mechanisms of growth plate maturation and epiphyseal fusion.

Longitudinal growth occurs within the long bones at the growth plate. During childhood, the growth plate matures, its total width decreases and eventually it disappears at the end of puberty with complete replacement by bone along with cessation of longitudinal growth. The exact mechanism of epiphyseal fusion is still not completely understood and experimental studies are complicated by the fact that there is a species difference between humans and rabbits that do fuse their growth plates and rodents that do not. This mini review summarizes hypotheses and theories postulated in the literature regarding growth plate maturation and epiphyseal fusion. Growth factors, local regulators and hormones involved in growth plate maturation are described as well as four postulated hypotheses and theories regarding the final steps in epiphyseal fusion: apoptosis, autophagy, transdifferentiation and hypoxia. A better insight into the mechanisms of epiphyseal fusion may ultimately help to develop new strategies for the treatment of cartilage and growth disorders.