Quantitative histomorphometric analysis of the human growth plate from birth to adolescence

Longitudinal bone growth occurs via the transformation of growth plate cart ilage into bone through a series of cell and matrix changes, termed endocho ndral ossification, In this study, we characterize the development of trabe cular bone from growth plate cartilage in the human rib from birth to adole scence. The height of the proliferative and hypertrophic zones within the g rowth plate and the primary bone spongiosa decreased with increasing age, w ith the greatest change observed in the first year of postnatal life. Withi n these zones, an internal rearrangement of tissue structure occurred, The matrix volume fraction (either cartilage or bone) increased with age in eac h of the zones, A concomitant increase in cartilage septae thickness and bo ne trabecular thickness was observed. A decrease in cartilage septae number was seen in the proliferative zone and a decrease in bone trabeculae numbe r was also observed in the primary spongiosa, However, no difference in car tilage septae number was noted in the hypertrophic zone, the region at whic h cartilage is transformed into bone. Together the proliferative and hypert rophic regions of the growth plate and the bone primary spongiosa appear to constitute the active growth region, with concomitant changes observed tha t result in longitudinal growth. In contrast, bone mineral volume in the se condary spongiosa was stable over the ages examined; however, trabecular ar chitecture underwent consolidation as trabecular number decreased and trabe cular thickness increased, The integration of the structural transformation from cartilage to bone is crucial in achieving the dual purposes of longit udinal growth and peak bone mass. The structure developed during childhood will have an important bearing on the response to bone-altering disease in later life. (Bone 27:495-501; 2000) (C) 2000 by Elsevier Science Inc. All r ights reserved.