3.5 - Osteoporosis

Abstract

Osteoporosis is a disease characterized by a decrease in bone mass and a deterioration in the architecture of the bones, which leads to an enhanced fragility of the skeleton, and therefore, to a greater risk of fracture. A study group of the World Health Organization (WHO) has quantified this definition in women. Thus, osteoporosis is defined as being present when the bone mineral density (BMD) or bone mineral content (BMC) is over 2.5 standard deviations below the young adult reference mean. Osteoporosis is a very common disorder which will become even more common with the increase in life expectancy. The loss of bone has two distinct patterns. One is a continuous age-related linear decline in bone mass occurring in both women and men. A second predisposing factor for osteoporosis, in some patients, is a failure to achieve optimal peak bone mass during adolescence. It is clear that in women after menopause, the increased loss is due to elevated bone resorption following the loss of estrogens, possibly mediated—at least in part—by an increase in bone resorbing cytokines. The clinical manifestations of osteoporosis are fractures and their consequences. The fractures occur often spontaneously or after minimal trauma. Their location differs somewhat with age. Although reduced bone mass and macroarchitectural deterioration are the main causes of fracture, other factors like a higher propensity to fall and a decreased capacity to handle falls adequately, contribute to their occurrence. In general, treatments can be divided into two categories, namely those aimed at inhibiting bone loss, and those aimed at increasing bone mass.