Osteoporosis and bone functional adaptation: Mechanobiological regulation of bone architecture in growing and adult bone, a review

During life, bone is continually optimized for its load-bearing role by a p rocess of functionally adaptive (re)modelling. This process, which is more active in growing bone, is dominated by high-magnitude, high-rate strains, presented in an unusual distribution. Adaptation occurs at an organ level, involving changes in whole bone architecture and bone mass. The repetitive coordinated bone loading associated with habitual activity may have little role in the preservation of bone mass, and may even reduce the osteogenic p otential of an otherwise highly osteogenic stimulus. Cells of the osteocyte /osteoblast network are best placed to appreciate mechanical strain. Among the strain-related responses they show, is a reduced rate of apoptosis. Thi s may serve to regulate and target osteoclast activity. A more complete und erstanding of the stimuli and pathways involved in both the physiology and pathology of this structural homeostatic mechanism will allow the design of more appropriate exercise regimens and targeted pharmacological interventi ons to limit morbidity and mortality by reducing bone fragility.